Collapse regions in the biome inspector

Short tables, one-line single picks.

build.gradle.kts

@@ -34,7 +34,7 @@ plugins {
 }
 
 group = "com.volmit"
-version = "3.9.2-1.20.1-1.21.11"
+version = "3.9.2-1.20.1-26.3"
 
 apply<ApiGenerator>()
 
@@ -64,6 +64,8 @@ val color = "truecolor"
 val errorReporting = "true" == findProperty("errorReporting")
 
 val nmsBindings = mapOf(
+    "v26_3_R1" to "26.3.build.176-stable",
+    "v26_1_R1" to "26.1.2.build.74-stable",
     "v1_21_R7" to "1.21.11-R0.1-SNAPSHOT",
     "v1_21_R6" to "1.21.10-R0.1-SNAPSHOT",
     "v1_21_R5" to "1.21.8-R0.1-SNAPSHOT",
@@ -76,7 +78,9 @@ val nmsBindings = mapOf(
     "v1_20_R2" to "1.20.2-R0.1-SNAPSHOT",
     "v1_20_R1" to "1.20.1-R0.1-SNAPSHOT",
 )
-val jvmVersion = mapOf<String, Int>()
+val jvmVersion = mapOf("v26_3_R1" to 25, "v26_1_R1" to 25)
+// From 26.1 on the server is not obfuscated, so these bindings compile against Paper's dev bundle as-is.
+val userDevBindings = setOf("v26_3_R1", "v26_1_R1")
 nmsBindings.forEach { (key, value) ->
     project(":nms:$key") {
         apply<JavaPlugin>()
@@ -84,7 +88,7 @@ nmsBindings.forEach { (key, value) ->
         nmsBinding {
             jvm = jvmVersion.getOrDefault(key, 21)
             version = value
-            type = NMSBinding.Type.DIRECT
+            type = if (key in userDevBindings) NMSBinding.Type.USER_DEV else NMSBinding.Type.DIRECT
         }
 
         dependencies {
@@ -96,7 +100,7 @@ nmsBindings.forEach { (key, value) ->
 
     tasks.register<RunServer>("runServer-$key") {
         group = "servers"
-        minecraftVersion(value.split("-")[0])
+        minecraftVersion(value.substringBefore("-").substringBefore(".build"))
         minHeapSize = serverMinHeap
         maxHeapSize = serverMaxHeap
         pluginJars(tasks.jar.flatMap { it.archiveFile })
@@ -115,7 +119,7 @@ val included: Configuration by configurations.creating
 val jarJar: Configuration by configurations.creating
 dependencies {
     for (key in nmsBindings.keys) {
-        included(project(":nms:$key", "reobf"))
+        included(project(":nms:$key", if (key in userDevBindings) "runtimeElements" else "reobf"))
     }
     included(project(":core", "shadow"))
     jarJar(project(":core:agent"))
@@ -190,7 +194,7 @@ allprojects {
 
     java {
         toolchain {
-            languageVersion.set(JavaLanguageVersion.of(21))
+            languageVersion.set(JavaLanguageVersion.of(jvmVersion.getOrDefault(name, 21)))
         }
     }
 

buildSrc/build.gradle.kts

@@ -27,6 +27,6 @@ repositories {
 dependencies {
     implementation("org.ow2.asm:asm:9.8")
     implementation("com.github.VolmitSoftware:NMSTools:c88961416f")
-    implementation("io.papermc.paperweight:paperweight-userdev:2.0.0-beta.18")
+    implementation("io.papermc.paperweight:paperweight-userdev:2.0.0-beta.21")
     implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.10.2")
 }

buildSrc/src/main/kotlin/NMSBinding.kt

@@ -50,18 +50,7 @@ class NMSBinding : Plugin<Project> {
                 it.version.set(config.version)
             }
 
-            configurations.register(REOBF_CONFIG) { conf ->
-                conf.isCanBeConsumed = true
-                conf.isCanBeResolved = false
-                conf.attributes {
-                    it.attribute(Usage.USAGE_ATTRIBUTE, objects.named(Usage.JAVA_RUNTIME))
-                    it.attribute(Category.CATEGORY_ATTRIBUTE, objects.named(Category.LIBRARY))
-                    it.attribute(LibraryElements.LIBRARY_ELEMENTS_ATTRIBUTE, objects.named(LibraryElements.JAR))
-                    it.attribute(Bundling.BUNDLING_ATTRIBUTE, objects.named(Bundling.EXTERNAL))
-                    it.attribute(Obfuscation.OBFUSCATION_ATTRIBUTE, objects.named(Obfuscation.OBFUSCATED))
-                }
-                conf.outgoing.artifact(tasks.named("remap"))
-            }
+            registerReobfConfiguration("remap")
         }
 
         val (major, minor) = config.version.parseVersion()
@@ -71,6 +60,20 @@ class NMSBinding : Plugin<Project> {
         rootProject.tasks.named("prepareKotlinBuildScriptModel") { it.dependsOn("$path:convert") }
     }
 
+    private fun Project.registerReobfConfiguration(artifactTask: String) {
+        val conf = configurations.create(REOBF_CONFIG)
+        conf.isCanBeConsumed = true
+        conf.isCanBeResolved = false
+        conf.attributes {
+            it.attribute(Usage.USAGE_ATTRIBUTE, objects.named(Usage.JAVA_RUNTIME))
+            it.attribute(Category.CATEGORY_ATTRIBUTE, objects.named(Category.LIBRARY))
+            it.attribute(LibraryElements.LIBRARY_ELEMENTS_ATTRIBUTE, objects.named(LibraryElements.JAR))
+            it.attribute(Bundling.BUNDLING_ATTRIBUTE, objects.named(Bundling.EXTERNAL))
+            it.attribute(Obfuscation.OBFUSCATION_ATTRIBUTE, objects.named(Obfuscation.OBFUSCATED))
+        }
+        conf.outgoing.artifact(tasks.named(artifactTask))
+    }
+
     @DisableCachingByDefault
     abstract class ConversionTask @Inject constructor(type: Type) : DefaultTask() {
         private val pattern: Regex
@@ -163,8 +166,10 @@ class NMSBinding : Plugin<Project> {
 
 private val NEW_LINE = System.lineSeparator()
 private val NEW_LINE_BYTES = NEW_LINE.encodeToByteArray()
+// "1.21.11-R0.1-SNAPSHOT" -> (21, 11), "26.1.2.build.74-stable" -> (26, 1)
 private fun String.parseVersion() = substringBefore('-').split(".").let {
-    it[1].toInt() to it[2].toInt()
+    if (it[0] == "1") it[1].toInt() to it[2].toInt()
+    else it[0].toInt() to it[1].toInt()
 }
 
 class Config(

core/build.gradle.kts

@@ -52,7 +52,8 @@ val lib = "com.volmit.iris.util"
  */
 dependencies {
     // Provided or Classpath
-    compileOnly(libs.spigot)
+    compileOnly(libs.paper)
+    compileOnly(platform(libs.adventure.bom))
     compileOnly(libs.log4j.api)
     compileOnly(libs.log4j.core)
 
@@ -78,10 +79,6 @@ dependencies {
 
     // Dynamically Loaded
     slim(libs.paralithic)
-    slim(libs.paperlib)
-    slim(libs.adventure.api)
-    slim(libs.adventure.minimessage)
-    slim(libs.adventure.platform)
     slim(libs.bstats)
     slim(libs.sentry)
 
@@ -101,6 +98,8 @@ dependencies {
     slim(libs.byteBuddy.agent)
     slim(libs.dom4j)
     slim(libs.jaxen)
+    slim(libs.flatlaf)
+    slim(libs.flatlaf.extras)
 
     // Script Engine
     slim(libs.kotlin.stdlib)
@@ -146,8 +145,6 @@ slimJar {
     ))
 
     relocate("com.dfsek.paralithic", "$lib.paralithic")
-    relocate("io.papermc.lib", "$lib.paper")
-    relocate("net.kyori", "$lib.kyori")
     relocate("org.bstats", "$lib.metrics")
     relocate("io.sentry", "$lib.sentry")
     relocate("org.apache.maven", "$lib.maven")

core/src/main/java/com/volmit/iris/Iris.java

@@ -31,6 +31,7 @@ import com.volmit.iris.core.nms.INMS;
 import com.volmit.iris.core.pregenerator.LazyPregenerator;
 import com.volmit.iris.core.service.StudioSVC;
 import com.volmit.iris.core.tools.IrisToolbelt;
+import com.volmit.iris.core.world.WorldStorage;
 import com.volmit.iris.engine.EnginePanic;
 import com.volmit.iris.engine.object.IrisCompat;
 import com.volmit.iris.engine.object.IrisDimension;
@@ -86,13 +87,14 @@ public class Iris extends VolmitPlugin implements Listener {
     private static final Queue<Runnable> syncJobs = new ShurikenQueue<>();
 
     public static Iris instance;
-    public static Bindings.Adventure audiences;
     public static MultiverseCoreLink linkMultiverseCore;
     public static IrisCompat compat;
     public static FileWatcher configWatcher;
     public static ChunkTickets tickets;
     private static VolmitSender sender;
     private static Thread shutdownHook;
+    private static final String STUDIO_WORLDS_FOLDER = "iris";
+    private static final String NMS_BINDINGS_PACKAGE = "com.volmit.iris.core.nms.v";
 
     static {
         try {
@@ -435,11 +437,11 @@ public class Iris extends VolmitPlugin implements Listener {
 
     private void enable() {
         services = new KMap<>();
-        setupAudience();
         Bindings.setupSentry();
         initialize("com.volmit.iris.core.service").forEach((i) -> services.put((Class<? extends IrisService>) i.getClass(), (IrisService) i));
-        IO.delete(new File("iris"));
+        IO.delete(WorldStorage.get().worldFolder(STUDIO_WORLDS_FOLDER));
         compat = IrisCompat.configured(getDataFile("compat.json"));
+        adoptLegacyWorldData();
         ServerConfigurator.configure();
         IrisSafeguard.execute();
         getSender().setTag(getTag());
@@ -466,6 +468,19 @@ public class Iris extends VolmitPlugin implements Listener {
         });
     }
 
+    private void adoptLegacyWorldData() {
+        WorldStorage storage = WorldStorage.get();
+        for (String worldName : IrisWorlds.readKnownWorldNames()) {
+            try {
+                storage.adoptLegacyData(worldName);
+            } catch (Throwable e) {
+                Iris.error("Failed to move the Iris data of " + worldName + " to its new world folder!");
+                Iris.reportError(e);
+                e.printStackTrace();
+            }
+        }
+    }
+
     public void addShutdownHook() {
         if (shutdownHook != null) {
             Runtime.getRuntime().removeShutdownHook(shutdownHook);
@@ -532,36 +547,47 @@ public class Iris extends VolmitPlugin implements Listener {
         }
     }
 
-    private void setupAudience() {
-        try {
-            audiences = new Bindings.Adventure(this);
-        } catch (Throwable e) {
-            e.printStackTrace();
-            IrisSettings.get().getGeneral().setUseConsoleCustomColors(false);
-            IrisSettings.get().getGeneral().setUseCustomColorsIngame(false);
-            Iris.error("Failed to setup Adventure API... No custom colors :(");
-        }
-    }
-
     public void postShutdown(Runnable r) {
         postShutdown.add(r);
     }
 
     public void onEnable() {
+        if (!isPaperServer()) {
+            getLogger().severe("Iris requires Paper or a Paper fork (Purpur, Pufferfish, ...). Spigot and CraftBukkit are not supported.");
+            Bukkit.getPluginManager().disablePlugin(this);
+            return;
+        }
         enable();
         super.onEnable();
         Bukkit.getPluginManager().registerEvents(this, this);
     }
 
     public void onDisable() {
-        if (IrisSafeguard.isForceShutdown()) return;
+        if (services == null || IrisSafeguard.isForceShutdown()) return;
         services.values().forEach(IrisService::onDisable);
         Bukkit.getScheduler().cancelTasks(this);
         HandlerList.unregisterAll((Plugin) this);
         postShutdown.forEach(Runnable::run);
         super.onDisable();
 
-        J.attempt(new JarScanner(instance.getJarFile(), "", false)::scanAll);
+        J.attempt(() -> new JarScanner(instance.getJarFile(), "", false).scanAll(Iris::isForRunningServer));
+    }
+
+    private static boolean isForRunningServer(String className) {
+        // Older servers log errors for the bindings compiled for a newer Java version.
+        if (!className.startsWith(NMS_BINDINGS_PACKAGE)) {
+            return true;
+        }
+        return className.startsWith(INMS.get().getClass().getPackageName() + ".");
+    }
+
+    private static boolean isPaperServer() {
+        try {
+            World.class.getMethod("getChunkAtAsync", int.class, int.class, boolean.class, boolean.class);
+            return true;
+        } catch (NoSuchMethodException e) {
+            return false;
+        }
     }
 
     private void setupPapi() {
@@ -651,7 +677,7 @@ public class Iris extends VolmitPlugin implements Listener {
                 .name(worldName)
                 .seed(1337)
                 .environment(dim.getEnvironment())
-                .worldFolder(new File(Bukkit.getWorldContainer(), worldName))
+                .worldFolder(WorldStorage.get().worldFolder(worldName))
                 .minHeight(dim.getMinHeight())
                 .maxHeight(dim.getMaxHeight())
                 .build();
@@ -673,7 +699,7 @@ public class Iris extends VolmitPlugin implements Listener {
 
     @Nullable
     public static IrisDimension loadDimension(@NonNull String worldName, @NonNull String id) {
-        File pack = new File(Bukkit.getWorldContainer(), String.join(File.separator, worldName, "iris", "pack"));
+        File pack = new File(WorldStorage.get().worldFolder(worldName), "iris/pack");
         var dimension = pack.isDirectory() ? IrisData.get(pack).getDimensionLoader().load(id) : null;
         if (dimension == null) dimension = IrisData.loadAnyDimension(id, null);
         if (dimension == null) {

core/src/main/java/com/volmit/iris/core/IrisSettings.java

@@ -147,11 +147,35 @@ public class IrisSettings {
 
     @Data
     public static class IrisSettingsPregen {
+        private static final int MIN_RESIDENT_TECTONIC_PLATES = 16;
+        private static final double MANTLE_HEAP_FRACTION = 0.6D;
+        private static final int MEASURED_PLATE_MEGABYTES = 38;
+        private static final int MEASURED_WORLD_HEIGHT = 1088;
+
         public boolean useCacheByDefault = true;
         public boolean useHighPriority = false;
         public boolean useVirtualThreads = false;
         public boolean useTicketQueue = true;
         public int maxConcurrency = 256;
+        public int maxResidentTectonicPlates = 96;
+        public int mantleBackpressureWaitMs = 25;
+        public int mantleBackpressureTimeoutMs = 60_000;
+
+        public int getEffectiveResidentTectonicPlates(int worldHeight) {
+            // Mantle chunks only hold the sections something was written to, so shorter worlds keep the measured size.
+            double heightScale = Math.max(1D, (double) worldHeight / MEASURED_WORLD_HEIGHT);
+            double plateMegabytes = MEASURED_PLATE_MEGABYTES * heightScale;
+            int heapBudget = (int) Math.floor(MANTLE_HEAP_FRACTION * getHardware.getProcessMemory() / plateMegabytes);
+            return Math.max(MIN_RESIDENT_TECTONIC_PLATES, Math.min(maxResidentTectonicPlates, heapBudget));
+        }
+
+        public int getMantleBackpressureWaitMs() {
+            return Math.max(5, Math.min(mantleBackpressureWaitMs, 1_000));
+        }
+
+        public int getMantleBackpressureTimeoutMs() {
+            return Math.max(5_000, Math.min(mantleBackpressureTimeoutMs, 600_000));
+        }
     }
 
     @Data
@@ -242,6 +266,7 @@ public class IrisSettings {
         public boolean useServerLaunchedGuis = true;
         public boolean maximumPregenGuiFPS = false;
         public boolean colorMode = true;
+        public String theme = "auto";
     }
 
     @Data

core/src/main/java/com/volmit/iris/core/IrisWorlds.java

@@ -5,6 +5,7 @@ import com.google.gson.GsonBuilder;
 import com.google.gson.reflect.TypeToken;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.core.world.WorldStorage;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.object.IrisDimension;
 import com.volmit.iris.util.collection.KMap;
@@ -17,7 +18,9 @@ import java.io.File;
 import java.io.IOException;
 import java.io.OutputStreamWriter;
 import java.lang.reflect.Type;
+import java.util.HashSet;
 import java.util.Objects;
+import java.util.Set;
 import java.util.stream.Stream;
 
 public class IrisWorlds {
@@ -34,24 +37,32 @@ public class IrisWorlds {
     }
 
     public static IrisWorlds get() {
-        return cache.aquire(() -> {
-            File file = Iris.instance.getDataFile("worlds.json");
-            if (!file.exists()) {
-                return new IrisWorlds(new KMap<>());
-            }
+        return cache.aquire(() -> new IrisWorlds(readWorldsFile()));
+    }
 
-            try {
-                String json = IO.readAll(file);
-                KMap<String, String> worlds = GSON.fromJson(json, TYPE);
-                return new IrisWorlds(Objects.requireNonNullElseGet(worlds, KMap::new));
-            } catch (Throwable e) {
-                Iris.error("Failed to load worlds.json!");
-                e.printStackTrace();
-                Iris.reportError(e);
-            }
+    public static Set<String> readKnownWorldNames() {
+        Set<String> names = new HashSet<>(readWorldsFile().keySet());
+        names.addAll(readBukkitWorlds().keySet());
+        return names;
+    }
 
-            return new IrisWorlds(new KMap<>());
-        });
+    private static KMap<String, String> readWorldsFile() {
+        File file = Iris.instance.getDataFile("worlds.json");
+        if (!file.exists()) {
+            return new KMap<>();
+        }
+
+        try {
+            String json = IO.readAll(file);
+            KMap<String, String> worlds = GSON.fromJson(json, TYPE);
+            return Objects.requireNonNullElseGet(worlds, KMap::new);
+        } catch (Throwable e) {
+            Iris.error("Failed to load worlds.json!");
+            e.printStackTrace();
+            Iris.reportError(e);
+        }
+
+        return new KMap<>();
     }
 
     public void put(String name, String type) {
@@ -85,7 +96,7 @@ public class IrisWorlds {
     }
 
     public void clean() {
-        dirty = worlds.entrySet().removeIf(entry -> !new File(Bukkit.getWorldContainer(), entry.getKey() + "/iris/pack/dimensions/" + entry.getValue() + ".json").exists());
+        dirty = worlds.entrySet().removeIf(entry -> !new File(WorldStorage.get().worldFolder(entry.getKey()), "iris/pack/dimensions/" + entry.getValue() + ".json").exists());
     }
 
     public synchronized void save() {

core/src/main/java/com/volmit/iris/core/ServerConfigurator.java

@@ -23,6 +23,7 @@ import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.core.nms.INMS;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.core.nms.datapack.IDataFixer;
+import com.volmit.iris.core.world.WorldStorage;
 import com.volmit.iris.engine.object.*;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
@@ -97,10 +98,7 @@ public class ServerConfigurator {
         if (!IrisSettings.get().getGeneral().forceMainWorld.isEmpty()) {
             return new KList<File>().qadd(new File(Bukkit.getWorldContainer(), IrisSettings.get().getGeneral().forceMainWorld + "/datapacks"));
         }
-        KList<File> worlds = new KList<>();
-        Bukkit.getServer().getWorlds().forEach(w -> worlds.add(new File(w.getWorldFolder(), "datapacks")));
-        if (worlds.isEmpty()) worlds.add(new File(Bukkit.getWorldContainer(), ServerProperties.LEVEL_NAME + "/datapacks"));
-        return worlds;
+        return WorldStorage.get().datapackFolders();
     }
 
     public static boolean installDataPacks(boolean fullInstall) {
@@ -198,7 +196,7 @@ public class ServerConfigurator {
                 }
             }
         }
-        String key = getWorld(dimension.getLoader());
+        String key = worldFolderNameOf(dimension.getLoader());
         if (key == null) key = dimension.getLoadKey();
         else key += "/" + dimension.getLoadKey();
 
@@ -247,14 +245,13 @@ public class ServerConfigurator {
     }
 
     @Nullable
-    public static String getWorld(@NonNull IrisData data) {
-        String worldContainer = Bukkit.getWorldContainer().getAbsolutePath();
-        if (!worldContainer.endsWith(File.separator)) worldContainer += File.separator;
-        
-        String path = data.getDataFolder().getAbsolutePath();
-        if (!path.startsWith(worldContainer)) return null;
-        int l = path.endsWith(File.separator) ? 11 : 10;
-        return path.substring(worldContainer.length(), path.length() - l);
+    private static String worldFolderNameOf(IrisData data) {
+        File pack = data.getDataFolder();
+        File iris = pack.getParentFile();
+        if (iris == null || iris.getParentFile() == null || !pack.getName().equals("pack") || !iris.getName().equals("iris")) {
+            return null;
+        }
+        return iris.getParentFile().getName();
     }
 
     @SneakyThrows

core/src/main/java/com/volmit/iris/core/commands/CommandIris.java

@@ -23,6 +23,7 @@ import com.volmit.iris.core.IrisSettings;
 import com.volmit.iris.core.nms.INMS;
 import com.volmit.iris.core.service.StudioSVC;
 import com.volmit.iris.core.tools.IrisToolbelt;
+import com.volmit.iris.core.world.WorldStorage;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.object.IrisDimension;
 import com.volmit.iris.util.collection.KList;
@@ -32,11 +33,8 @@ import com.volmit.iris.util.decree.annotations.Decree;
 import com.volmit.iris.util.decree.annotations.Param;
 import com.volmit.iris.util.decree.specialhandlers.NullablePlayerHandler;
 import com.volmit.iris.util.format.C;
-import com.volmit.iris.util.io.IO;
-import com.volmit.iris.util.misc.ServerProperties;
 import com.volmit.iris.util.plugin.VolmitSender;
 import com.volmit.iris.util.scheduling.J;
-import lombok.SneakyThrows;
 import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.configuration.ConfigurationSection;
@@ -45,7 +43,6 @@ import org.bukkit.entity.Player;
 import org.bukkit.scheduler.BukkitRunnable;
 
 import java.io.*;
-import java.util.List;
 import java.util.concurrent.atomic.AtomicReference;
 
 import static com.volmit.iris.core.service.EditSVC.deletingWorld;
@@ -93,7 +90,7 @@ public class CommandIris implements DecreeExecutor {
             return;
         }
 
-        if (new File(Bukkit.getWorldContainer(), name).exists()) {
+        if (WorldStorage.get().worldFolder(name).exists()) {
             sender().sendMessage(C.RED + "That folder already exists!");
             return;
         }
@@ -108,9 +105,10 @@ public class CommandIris implements DecreeExecutor {
                     .studio(false)
                     .create();
             if (main) {
+                WorldStorage storage = WorldStorage.get();
                 Runtime.getRuntime().addShutdownHook(mainWorld.updateAndGet(old -> {
                     if (old != null) Runtime.getRuntime().removeShutdownHook(old);
-                    return new Thread(() -> updateMainWorld(name));
+                    return new Thread(() -> makeMainWorld(storage, name));
                 }));
             }
         } catch (Throwable e) {
@@ -125,20 +123,12 @@ public class CommandIris implements DecreeExecutor {
         if (main) sender().sendMessage(C.GREEN + "Your world will automatically be set as the main world when the server restarts.");
     }
 
-    @SneakyThrows
-    private void updateMainWorld(String newName) {
-        File worlds = Bukkit.getWorldContainer();
-        var data = ServerProperties.DATA;
-        try (var in = new FileInputStream(ServerProperties.SERVER_PROPERTIES)) {
-            data.load(in);
-        }
-        for (String sub : List.of("datapacks", "playerdata", "advancements", "stats")) {
-            IO.copyDirectory(new File(worlds, ServerProperties.LEVEL_NAME + "/" + sub).toPath(), new File(worlds, newName + "/" + sub).toPath());
-        }
-
-        data.setProperty("level-name", newName);
-        try (var out = new FileOutputStream(ServerProperties.SERVER_PROPERTIES)) {
-            data.store(out, null);
+    private static void makeMainWorld(WorldStorage storage, String worldName) {
+        try {
+            storage.makeMainWorld(worldName);
+        } catch (Throwable e) {
+            Iris.error("Failed to make " + worldName + " the main world!");
+            e.printStackTrace();
         }
     }
 
@@ -470,6 +460,7 @@ public class CommandIris implements DecreeExecutor {
             String world
     ) {
         World worldloaded = Bukkit.getWorld(world);
+        WorldStorage.get().adoptLegacyData(world);
         worldNameToCheck = world;
         boolean worldExists = doesWorldExist(worldNameToCheck);
         WorldEngine = world;
@@ -479,8 +470,7 @@ public class CommandIris implements DecreeExecutor {
             return;
         }
 
-        String pathtodim = world + File.separator +"iris"+File.separator +"pack"+File.separator +"dimensions"+File.separator;
-        File directory = new File(Bukkit.getWorldContainer(), pathtodim);
+        File directory = new File(WorldStorage.get().worldFolder(world), "iris/pack/dimensions");
 
         String dimension = null;
         if (directory.exists() && directory.isDirectory()) {
@@ -533,8 +523,7 @@ public class CommandIris implements DecreeExecutor {
     }
 
     boolean doesWorldExist(String worldName) {
-        File worldContainer = Bukkit.getWorldContainer();
-        File worldDirectory = new File(worldContainer, worldName);
+        File worldDirectory = WorldStorage.get().worldFolder(worldName);
         return worldDirectory.exists() && worldDirectory.isDirectory();
     }
 }

core/src/main/java/com/volmit/iris/core/commands/CommandLazyPregen.java

@@ -54,7 +54,7 @@ public class CommandLazyPregen implements DecreeExecutor {
             ) {
 
         worldName = world.getName();
-        File worldDirectory = new File(Bukkit.getWorldContainer(), world.getName());
+        File worldDirectory = world.getWorldFolder();
         File lazyFile = new File(worldDirectory, "lazygen.json");
         if (lazyFile.exists()) {
             sender().sendMessage(C.BLUE + "Lazy pregen is already in progress");

core/src/main/java/com/volmit/iris/core/commands/CommandStudio.java

@@ -20,8 +20,10 @@ package com.volmit.iris.core.commands;
 
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.IrisSettings;
+import com.volmit.iris.core.gui.GuiHost;
+import com.volmit.iris.core.gui.MapWindow;
 import com.volmit.iris.core.gui.NoiseExplorerGUI;
-import com.volmit.iris.core.gui.VisionGUI;
+import com.volmit.iris.core.gui.PaletteExplorerStart;
 import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.core.project.IrisProject;
 import com.volmit.iris.core.service.ConversionSVC;
@@ -40,7 +42,6 @@ import com.volmit.iris.util.decree.annotations.Decree;
 import com.volmit.iris.util.decree.annotations.Param;
 import com.volmit.iris.util.format.C;
 import com.volmit.iris.util.format.Form;
-import com.volmit.iris.util.function.Function2;
 import com.volmit.iris.util.function.NoiseProvider;
 import com.volmit.iris.util.interpolation.InterpolationMethod;
 import com.volmit.iris.util.io.IO;
@@ -59,7 +60,6 @@ import com.volmit.iris.util.scheduling.J;
 import com.volmit.iris.util.scheduling.O;
 import com.volmit.iris.util.scheduling.PrecisionStopwatch;
 import com.volmit.iris.util.scheduling.jobs.ParallelRadiusJob;
-import io.papermc.lib.PaperLib;
 import org.bukkit.*;
 import org.bukkit.event.inventory.InventoryType;
 import org.bukkit.inventory.Inventory;
@@ -80,7 +80,6 @@ import java.util.Objects;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicInteger;
-import java.util.function.Supplier;
 
 @Decree(name = "studio", aliases = {"std", "s"}, description = "Studio Commands", studio = true)
 public class CommandStudio implements DecreeExecutor {
@@ -247,11 +246,47 @@ public class CommandStudio implements DecreeExecutor {
         engine().getExecution().execute(script.getLoadKey());
     }
 
-    @Decree(description = "Open the noise explorer (External GUI)", aliases = {"nmap", "n"})
+    @Decree(description = "Open the map on its noise explorer (External GUI)", aliases = {"nmap", "n"})
     public void noise() {
         if (noGUI()) return;
-        sender().sendMessage(C.GREEN + "Opening Noise Explorer!");
-        NoiseExplorerGUI.launch();
+        Engine playerEngine = engine();
+        Engine engine = playerEngine != null ? playerEngine : GuiHost.findActiveEngine();
+        World world = engine == null ? null : engine.getWorld().realWorld();
+        if (world == null) {
+            sender().sendMessage(C.RED + "Open a studio or stand in an Iris world to explore its noise!");
+            return;
+        }
+        Location center = playerEngine != null ? player().getLocation() : null;
+        sender().sendMessage(C.GREEN + "Opening the map on its noise!");
+        MapWindow.openNoise(new PaletteExplorerStart(
+                engine,
+                world.getUID(),
+                sender().isPlayer() ? player().getUniqueId() : null,
+                null,
+                center == null ? 0D : center.getX(),
+                center == null ? 0D : center.getZ()
+        ));
+    }
+
+    @Decree(description = "Preview the palettes around you (External GUI)", aliases = "pal", origin = DecreeOrigin.PLAYER)
+    public void palette() {
+        if (noGUI()) return;
+        Engine engine = engine();
+        if (engine == null) {
+            sender().sendMessage(C.RED + "Stand in an Iris world to preview its palettes!");
+            return;
+        }
+        Location location = player().getLocation();
+        IrisBiome surfaceBiome = engine.getSurfaceBiome(location.getBlockX(), location.getBlockZ());
+        sender().sendMessage(C.GREEN + "Opening the map on its palettes!");
+        MapWindow.openPalettes(new PaletteExplorerStart(
+                engine,
+                location.getWorld().getUID(),
+                player().getUniqueId(),
+                surfaceBiome == null ? null : surfaceBiome.getLoadKey(),
+                location.getX(),
+                location.getZ()
+        ));
     }
 
     @Decree(description = "Charges all spawners in the area", aliases = "zzt", origin = DecreeOrigin.PLAYER)
@@ -273,16 +308,7 @@ public class CommandStudio implements DecreeExecutor {
     ) {
         if (noGUI()) return;
         sender().sendMessage(C.GREEN + "Opening Noise Explorer!");
-
-        Supplier<Function2<Double, Double, Double>> l = () -> {
-
-            if (generator == null) {
-                return (x, z) -> 0D;
-            }
-
-            return (x, z) -> generator.getHeight(x, z, new RNG(seed).nextParallelRNG(3245).lmax());
-        };
-        NoiseExplorerGUI.launch(l, "Custom Generator");
+        NoiseExplorerGUI.launchGeneratorKey(engine(), generator == null ? null : generator.getLoadKey(), generator, seed);
     }
 
     @Decree(description = "Hotload a studio", aliases = {"reload", "h"})
@@ -457,7 +483,15 @@ public class CommandStudio implements DecreeExecutor {
             return;
         }
 
-        VisionGUI.launch(IrisToolbelt.access(world).getEngine(), 0);
+        Location center = sender().isPlayer() && player().getWorld().equals(world) ? player().getLocation() : null;
+        MapWindow.openMap(new PaletteExplorerStart(
+                IrisToolbelt.access(world).getEngine(),
+                world.getUID(),
+                sender().isPlayer() ? player().getUniqueId() : null,
+                null,
+                center == null ? 0D : center.getX(),
+                center == null ? 0D : center.getZ()
+        ));
         sender().sendMessage(C.GREEN + "Opening map!");
     }
 
@@ -689,7 +723,7 @@ public class CommandStudio implements DecreeExecutor {
 
         sender().sendMessage(C.GREEN + "Sending you to the studio world!");
         var player = player();
-        PaperLib.teleportAsync(player(), Iris.service(StudioSVC.class)
+        player.teleportAsync(Iris.service(StudioSVC.class)
                 .getActiveProject()
                 .getActiveProvider()
                 .getTarget()
@@ -748,7 +782,6 @@ public class CommandStudio implements DecreeExecutor {
             pw.println("Iris Version: " + Iris.instance.getDescription().getVersion());
             pw.println("Bukkit Version: " + Bukkit.getBukkitVersion());
             pw.println("MC Version: " + Bukkit.getVersion());
-            pw.println("PaperSpigot: " + (PaperLib.isPaper() ? "Yup!" : "Nope!"));
             pw.println("Report Captured At: " + new Date());
             pw.println("Chunks: (" + chunks.size() + "): ");
 
@@ -879,6 +912,10 @@ public class CommandStudio implements DecreeExecutor {
             sender().sendMessage(C.RED + "You must have server launched GUIs enabled in the settings!");
             return true;
         }
+        if (!GuiHost.isAvailable()) {
+            sender().sendMessage(C.RED + "This server runs without a desktop, so it cannot open windows!");
+            return true;
+        }
         return false;
     }
 

core/src/main/java/com/volmit/iris/core/commands/CommandTurboPregen.java

@@ -47,7 +47,7 @@ public class CommandTurboPregen implements DecreeExecutor {
             ) {
 
         worldName = world.getName();
-        File worldDirectory = new File(Bukkit.getWorldContainer(), world.getName());
+        File worldDirectory = world.getWorldFolder();
         File TurboFile = new File(worldDirectory, "turbogen.json");
         if (TurboFile.exists()) {
             if (TurboPregenerator.getInstance() != null) {
@@ -93,7 +93,7 @@ public class CommandTurboPregen implements DecreeExecutor {
     @Decree(description = "Stop the active pregeneration task", aliases = "x")
     public void stop(@Param(aliases = "world", description = "The world to pause") World world) throws IOException {
         TurboPregenerator turboPregenInstance = TurboPregenerator.getInstance();
-        File worldDirectory = new File(Bukkit.getWorldContainer(), world.getName());
+        File worldDirectory = world.getWorldFolder();
         File turboFile = new File(worldDirectory, "turbogen.json");
 
         if (turboPregenInstance != null) {
@@ -117,7 +117,7 @@ public class CommandTurboPregen implements DecreeExecutor {
             TurboPregenerator.setPausedTurbo(world);
             sender().sendMessage(C.GREEN + "Paused/unpaused Turbo Pregen, now: " + (TurboPregenerator.isPausedTurbo(world) ? "Paused" : "Running") + ".");
         } else {
-            File worldDirectory = new File(Bukkit.getWorldContainer(), world.getName());
+            File worldDirectory = world.getWorldFolder();
             File TurboFile = new File(worldDirectory, "turbogen.json");
             if (TurboFile.exists()){
                 TurboPregenerator.loadTurboGenerator(world.getName());

core/src/main/java/com/volmit/iris/core/gui/BiomeExplorer.java

@@ -0,0 +1,208 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.PickMeasuring.TypedSpread;
+import com.volmit.iris.core.gui.components.PickDisplay;
+import com.volmit.iris.engine.IrisComplex;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.InferredType;
+import com.volmit.iris.engine.object.IrisRegion;
+import com.volmit.iris.util.stream.ProceduralStream;
+
+import javax.swing.JComponent;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.EnumMap;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+/**
+ * The biome view's explorer: every region picks the biomes on its ground from its own biome lists, so for each region
+ * in view it shows how its noise, or in hybrid terrain the height, picks them.
+ */
+final class BiomeExplorer {
+    private final Supplier<Engine> engineSource;
+    private final PickInspectorPanel inspector;
+    private final LatestMeasurement<Measurement> measurer = new LatestMeasurement<>("Iris Biome Explorer");
+    private MapCensus.ViewArea latestArea;
+    private MapCensus.ViewArea measuredArea;
+
+    /**
+     * @param onDisplayChosen receives how the map should draw the picks
+     */
+    BiomeExplorer(Supplier<Engine> engineSource, Consumer<PickDisplay> onDisplayChosen) {
+        this.engineSource = engineSource;
+        this.inspector = new PickInspectorPanel("Biomes", onDisplayChosen);
+    }
+
+    PickInspectorPanel inspector() {
+        return inspector;
+    }
+
+    /**
+     * Measures the regions in this area and how they pick their biomes, unless that was already done.
+     */
+    void measure(MapCensus.ViewArea area) {
+        latestArea = area;
+        if (area == null || area.equals(measuredArea)) {
+            return;
+        }
+        measuredArea = area;
+        measurer.measure(() -> measurePicks(area), this::show);
+    }
+
+    /**
+     * The pack changed, so the regions and their biomes are read again.
+     */
+    void refresh() {
+        measuredArea = null;
+        measure(latestArea);
+    }
+
+    void close() {
+        measurer.close();
+    }
+
+    private void show(Measurement measurement) {
+        List<PickInspectorPanel.Section> sections = new ArrayList<>();
+        for (RegionPicks region : measurement.regions()) {
+            List<JComponent> charts = region.coverage() != null
+                    ? List.of(PickInspectorPanel.heightChart(region.coverage()))
+                    : region.spreads().stream()
+                    .map(spread -> (JComponent) inspector.noiseChart(spread, "Biomes", region.key() + "/" + spread.title()))
+                    .toList();
+            sections.add(new PickInspectorPanel.Section(region.key(), region.name(), region.color(), region.share(),
+                    biomeCountText(region.biomeCount()), charts, region.notes()));
+        }
+        String detail = measurement.hybrid()
+                ? "Hybrid terrain · each region picks biomes by height"
+                : "Each region splits its own biome noise by rarity";
+        inspector.showRegionSections(detail, sections, measurement.notes());
+    }
+
+    private static String biomeCountText(int count) {
+        return count == 1 ? "1 biome" : count + " biomes";
+    }
+
+    private Measurement measurePicks(MapCensus.ViewArea area) {
+        Engine engine = engineSource.get();
+        IrisComplex complex = engine == null ? null : engine.getComplex();
+        if (complex == null) {
+            return null;
+        }
+        Map<IrisRegion, RegionSamples> samplesByRegion = new IdentityHashMap<>();
+        int[] total = {0};
+        PickMeasuring.forEachSample(area, (x, z) -> {
+            IrisRegion region = complex.getRegionStream().get(x, z);
+            if (region == null) {
+                return;
+            }
+            total[0]++;
+            samplesByRegion.computeIfAbsent(region, subject -> new RegionSamples(engine, complex, subject)).add(x, z);
+        });
+        List<RegionPicks> regions = samplesByRegion.values().stream()
+                .sorted(Comparator.comparingInt(RegionSamples::count).reversed())
+                .map(samples -> samples.picks(engine, total[0]))
+                .toList();
+        List<String> notes = new ArrayList<>();
+        if (complex.isHybridTerrain()) {
+            notes.add(PickMeasuring.hybridNoiseNote());
+        } else {
+            PickMeasuring.addRarityNotes(notes, complex, regions.stream().flatMap(region -> region.spreads().stream()).toList());
+        }
+        notes.add(PickMeasuring.measuredNote());
+        return new Measurement(complex.isHybridTerrain(), regions, notes);
+    }
+
+    /**
+     * The spots in view one region owns. The biome view shows each spot's base biome, which the region picks from the
+     * biome list of the spot's continent type.
+     */
+    private static final class RegionSamples {
+        private final IrisComplex complex;
+        private final IrisRegion region;
+        private final List<TypedSpread> spreads;
+        private final Map<InferredType, ProceduralStream<Double>> noiseByType = new EnumMap<>(InferredType.class);
+        private final List<Integer> pickingHeights = new ArrayList<>();
+        private int count;
+
+        private RegionSamples(Engine engine, IrisComplex complex, IrisRegion region) {
+            this.complex = complex;
+            this.region = region;
+            this.spreads = complex.isHybridTerrain() ? List.of() : PickMeasuring.biomeSpreads(engine, complex, region);
+        }
+
+        private void add(double x, double z) {
+            count++;
+            if (complex.isHybridTerrain()) {
+                pickingHeights.add((int) Math.round(complex.getPlacementHeightStream().get(x, z)));
+                return;
+            }
+            InferredType type = complex.getBridgeStream().get(x, z);
+            for (TypedSpread typed : spreads) {
+                if (typed.type() == type) {
+                    typed.spread().add(noiseByType.computeIfAbsent(type, shown -> complex.biomePickNoiseStream(region, shown)).get(x, z));
+                }
+            }
+        }
+
+        private int count() {
+            return count;
+        }
+
+        private RegionPicks picks(Engine engine, int totalCount) {
+            double share = totalCount == 0 ? 0D : count / (double) totalCount;
+            String key = region.getLoadKey();
+            String name = region.getName();
+            int color = PickMeasuring.regionColor(engine, region);
+            List<String> notes = new ArrayList<>();
+            if (complex.isHybridTerrain()) {
+                List<RegionHeightCoverage.BiomeRange> ranges = PickMeasuring.biomeRanges(engine, region);
+                RegionHeightCoverage coverage = RegionHeightCoverage.measure(ranges,
+                        pickingHeights.stream().mapToInt(Integer::intValue).toArray());
+                notes.addAll(coverage.notes());
+                return new RegionPicks(key, name, color, share, ranges.size(), List.of(), coverage, notes);
+            }
+            List<TypedSpread> inView = spreads.stream().filter(typed -> typed.spread().sampleCount() > 0).toList();
+            PickMeasuring.addBiomeSpreadNotes(notes, inView);
+            PickMeasuring.addChildBiomeNote(notes, complex, region);
+            int biomeCount = (int) inView.stream()
+                    .flatMap(typed -> typed.spread().rows().stream())
+                    .map(row -> row.option().key())
+                    .distinct()
+                    .count();
+            return new RegionPicks(key, name, color, share, biomeCount, inView.stream().map(TypedSpread::spread).toList(),
+                    null, notes);
+        }
+    }
+
+    /**
+     * @param coverage how the region's biomes cover the heights in view in hybrid terrain, or null in biome terrain
+     */
+    private record RegionPicks(String key, String name, int color, double share, int biomeCount,
+                               List<NoisePickSpread> spreads, RegionHeightCoverage coverage, List<String> notes) {
+    }
+
+    private record Measurement(boolean hybrid, List<RegionPicks> regions, List<String> notes) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BiomeInfoNoise.java

@@ -0,0 +1,96 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import java.util.Random;
+
+// A copy of Minecraft's Biome.BIOME_INFO_NOISE, the 2D simplex noise swamps use to pick between their two grass colours.
+// Minecraft seeds it through a LegacyRandomSource, which draws the same numbers as java.util.Random.
+final class BiomeInfoNoise {
+    private static final long SEED = 2345L;
+    private static final int PERMUTATION_SIZE = 256;
+    private static final int GRADIENT_COUNT = 12;
+    private static final double SKEW = 0.5D * (Math.sqrt(3D) - 1D);
+    private static final double UNSKEW = (3D - Math.sqrt(3D)) / 6D;
+    private static final double CORNER_RADIUS = 0.5D;
+    private static final double OUTPUT_SCALE = 70D;
+    private static final int[][] GRADIENTS = {
+            {1, 1}, {-1, 1}, {1, -1}, {-1, -1},
+            {1, 0}, {-1, 0}, {1, 0}, {-1, 0},
+            {0, 1}, {0, -1}, {0, 1}, {0, -1}
+    };
+    private static final int[] PERMUTATION = createPermutation();
+
+    private BiomeInfoNoise() {
+    }
+
+    static float at(double x, double z) {
+        double skewOffset = (x + z) * SKEW;
+        int cellX = (int) Math.floor(x + skewOffset);
+        int cellZ = (int) Math.floor(z + skewOffset);
+        double unskewOffset = (cellX + cellZ) * UNSKEW;
+        double x0 = x - (cellX - unskewOffset);
+        double z0 = z - (cellZ - unskewOffset);
+        int stepX = x0 > z0 ? 1 : 0;
+        int stepZ = 1 - stepX;
+        double x1 = x0 - stepX + UNSKEW;
+        double z1 = z0 - stepZ + UNSKEW;
+        double x2 = x0 - 1D + 2D * UNSKEW;
+        double z2 = z0 - 1D + 2D * UNSKEW;
+        int wrappedX = cellX & 0xFF;
+        int wrappedZ = cellZ & 0xFF;
+        int gradient0 = permute(wrappedX + permute(wrappedZ)) % GRADIENT_COUNT;
+        int gradient1 = permute(wrappedX + stepX + permute(wrappedZ + stepZ)) % GRADIENT_COUNT;
+        int gradient2 = permute(wrappedX + 1 + permute(wrappedZ + 1)) % GRADIENT_COUNT;
+        return (float) (OUTPUT_SCALE * (corner(gradient0, x0, z0) + corner(gradient1, x1, z1) + corner(gradient2, x2, z2)));
+    }
+
+    private static double corner(int gradient, double x, double z) {
+        double falloff = CORNER_RADIUS - x * x - z * z;
+        if (falloff < 0D) {
+            return 0D;
+        }
+        falloff *= falloff;
+        return falloff * falloff * (GRADIENTS[gradient][0] * x + GRADIENTS[gradient][1] * z);
+    }
+
+    private static int permute(int index) {
+        return PERMUTATION[index & 0xFF];
+    }
+
+    // Minecraft draws three offsets first and discards them for this noise, so they are drawn here too to stay in step.
+    private static int[] createPermutation() {
+        Random random = new Random(SEED);
+        for (int discardedOffset = 0; discardedOffset < 3; discardedOffset++) {
+            random.nextDouble();
+        }
+        int[] permutation = new int[PERMUTATION_SIZE];
+        for (int i = 0; i < PERMUTATION_SIZE; i++) {
+            permutation[i] = i;
+        }
+        for (int i = 0; i < PERMUTATION_SIZE; i++) {
+            int swap = i + random.nextInt(PERMUTATION_SIZE - i);
+            int previous = permutation[i];
+            permutation[i] = permutation[swap];
+            permutation[swap] = previous;
+        }
+        return permutation;
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BiomePalette.java

@@ -0,0 +1,195 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisBiomePaletteLayer;
+import com.volmit.iris.engine.object.IrisBlockData;
+import com.volmit.iris.engine.object.IrisDecorator;
+import com.volmit.iris.util.collection.KList;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * One of the block palettes a biome places: a surface, sea or cave ceiling layer, its wall or slab blocks, or a
+ * decorator.
+ */
+record BiomePalette(String biomeKey, Kind kind, int index) {
+    private static final String ID_PREFIX = "palette:";
+    private static final char ID_SEPARATOR = '#';
+    private static final String SNIPPET_PREFIX = "snippet/";
+
+    enum Kind {
+        LAYER("Layer", "layers", SnippetFolder.BLOCK_PALETTES, true, true),
+        SEA_LAYER("Sea layer", "seaLayers", SnippetFolder.BLOCK_PALETTES, true, true),
+        CAVE_CEILING_LAYER("Cave ceiling layer", "caveCeilingLayers", SnippetFolder.BLOCK_PALETTES, true, true),
+        WALL("Wall", "wall", SnippetFolder.BLOCK_PALETTES, false, false),
+        SLAB("Slab", "slab", SnippetFolder.BLOCK_PALETTES, false, false),
+        DECORATOR("Decorator", "decorators", SnippetFolder.DECORATORS, false, true);
+
+        private final String label;
+        private final String jsonKey;
+        private final SnippetFolder snippetFolder;
+        private final boolean stacked;
+        private final boolean numbered;
+
+        Kind(String label, String jsonKey, SnippetFolder snippetFolder, boolean stacked, boolean numbered) {
+            this.label = label;
+            this.jsonKey = jsonKey;
+            this.snippetFolder = snippetFolder;
+            this.stacked = stacked;
+            this.numbered = numbered;
+        }
+
+        SnippetFolder snippetFolder() {
+            return snippetFolder;
+        }
+
+        /**
+         * Whether the palette is a stack of blocks with a thickness, rather than single blocks on walls or slopes.
+         */
+        boolean isStacked() {
+            return stacked;
+        }
+
+        /**
+         * The biome file's key holding these palettes: a list of them, or a single one for walls and slabs.
+         */
+        String jsonKey() {
+            return jsonKey;
+        }
+
+        // A biome without wall or slab blocks still has those palettes, just empty.
+        List<IrisBiomePaletteLayer> layersOf(IrisBiome biome) {
+            return switch (this) {
+                case LAYER -> biome.getLayers();
+                case SEA_LAYER -> biome.getSeaLayers();
+                case CAVE_CEILING_LAYER -> biome.getCaveCeilingLayers();
+                case WALL -> biome.getWall().getPalette().isEmpty() ? List.of() : List.of(biome.getWall());
+                case SLAB -> biome.getSlab().getPalette().isEmpty() ? List.of() : List.of(biome.getSlab());
+                case DECORATOR -> List.of();
+            };
+        }
+
+        // A decorator snippet that couldn't be found loads as an empty entry, which places nothing.
+        List<KList<IrisBlockData>> blockListsOf(IrisBiome biome) {
+            if (this != DECORATOR) {
+                return layersOf(biome).stream().map(IrisBiomePaletteLayer::getPalette).toList();
+            }
+            return biome.getDecorators().stream()
+                    .map(decorator -> decorator == null ? new KList<IrisBlockData>() : decorator.getPalette())
+                    .toList();
+        }
+    }
+
+    /**
+     * The folders under snippet/ that palettes can come from, named after the Iris type they hold.
+     */
+    enum SnippetFolder {
+        BLOCK_PALETTES("biome-palette", "Block palettes"),
+        DECORATORS("decorator", "Decorators");
+
+        private final String folder;
+        private final String label;
+
+        SnippetFolder(String folder, String label) {
+            this.folder = folder;
+            this.label = label;
+        }
+
+        String folder() {
+            return folder;
+        }
+
+        String label() {
+            return label;
+        }
+
+        /**
+         * The snippet's path inside this folder. Packs may leave the folder out, the way the snippet loader allows.
+         */
+        String pathOf(String reference) {
+            String path = reference.startsWith(SNIPPET_PREFIX) ? reference.substring(SNIPPET_PREFIX.length()) : reference;
+            return path.startsWith(folder + "/") ? path.substring(folder.length() + 1) : path;
+        }
+    }
+
+    static List<BiomePalette> allOf(String biomeKey, IrisBiome biome) {
+        List<BiomePalette> palettes = new ArrayList<>();
+        for (Kind kind : Kind.values()) {
+            List<KList<IrisBlockData>> blockLists = kind.blockListsOf(biome);
+            for (int index = 0; index < blockLists.size(); index++) {
+                if (!blockLists.get(index).isEmpty()) {
+                    palettes.add(new BiomePalette(biomeKey, kind, index));
+                }
+            }
+        }
+        return List.copyOf(palettes);
+    }
+
+    static BiomePalette fromId(String id) {
+        if (id == null || !id.startsWith(ID_PREFIX)) {
+            return null;
+        }
+        int indexSeparator = id.lastIndexOf(ID_SEPARATOR);
+        int kindSeparator = id.lastIndexOf(ID_SEPARATOR, indexSeparator - 1);
+        if (kindSeparator < ID_PREFIX.length()) {
+            return null;
+        }
+        return new BiomePalette(
+                id.substring(ID_PREFIX.length(), kindSeparator),
+                Kind.valueOf(id.substring(kindSeparator + 1, indexSeparator)),
+                Integer.parseInt(id.substring(indexSeparator + 1))
+        );
+    }
+
+    static boolean belongsTo(String id, String biomeKey) {
+        return id != null && id.startsWith(ID_PREFIX + biomeKey + ID_SEPARATOR);
+    }
+
+    String id() {
+        return ID_PREFIX + biomeKey + ID_SEPARATOR + kind.name() + ID_SEPARATOR + index;
+    }
+
+    String label() {
+        return kind.numbered ? kind.label + " " + index : kind.label;
+    }
+
+    String lowercaseLabel() {
+        return label().toLowerCase(Locale.ROOT);
+    }
+
+    /**
+     * The palette's blocks in the given copy of the biome, or null when a hotload removed it.
+     */
+    KList<IrisBlockData> blocksIn(IrisBiome biome) {
+        List<KList<IrisBlockData>> blockLists = kind.blockListsOf(biome);
+        return index < blockLists.size() ? blockLists.get(index) : null;
+    }
+
+    IrisBiomePaletteLayer layerIn(IrisBiome biome) {
+        return kind.layersOf(biome).get(index);
+    }
+
+    IrisDecorator decoratorIn(IrisBiome biome) {
+        return biome.getDecorators().get(index);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BiomePalettePlacement.java

@@ -0,0 +1,325 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.engine.decorator.IrisEngineDecorator;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisBiomePaletteLayer;
+import com.volmit.iris.engine.object.IrisBlockData;
+import com.volmit.iris.engine.object.IrisDecorationPart;
+import com.volmit.iris.engine.object.IrisDecorator;
+import com.volmit.iris.engine.object.IrisDimension;
+import com.volmit.iris.util.collection.KList;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.noise.CNG;
+import org.bukkit.block.data.Bisected;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * How thick one biome palette is at a spot and which noise picks its block there, sampled exactly the way the
+ * generator does for that kind of palette. The generator seeds each palette's noise from the first call it makes,
+ * so these use the same random sources the terrain, carving, post and decorator passes use.
+ */
+abstract class BiomePalettePlacement {
+    protected final IrisData data;
+
+    private BiomePalettePlacement(IrisData data) {
+        this.data = data;
+    }
+
+    static BiomePalettePlacement of(Engine engine, IrisBiome biome, BiomePalette palette) {
+        IrisData data = engine.getData();
+        RNG terrainRandom = new RNG(engine.getSeedManager().getTerrain());
+        RNG carveRandom = new RNG(engine.getSeedManager().getCarve());
+        RNG postRandom = new RNG(engine.getSeedManager().getPost());
+        int seaLevel = seaLevel(engine.getDimension());
+        return switch (palette.kind()) {
+            case LAYER -> new SurfaceLayer(biome, palette.index(), palette.layerIn(biome), terrainRandom, data);
+            case SEA_LAYER -> new LegacyStackedLayer(palette.layerIn(biome), data, terrainRandom.nextParallelRNG(palette.index()),
+                    biome.getLayerSeaHeightGenerators(terrainRandom, data), palette.index());
+            case CAVE_CEILING_LAYER -> new LegacyStackedLayer(palette.layerIn(biome), data, carveRandom.nextParallelRNG(palette.index()),
+                    biome.getLayerHeightGenerators(terrainRandom, data), palette.index());
+            case WALL -> new SingleBlocks(palette.layerIn(biome), data, carveRandom, seaLevel);
+            case SLAB -> new SingleBlocks(palette.layerIn(biome), data, postRandom, seaLevel);
+            case DECORATOR -> new Decorations(biome, palette.decoratorIn(biome), engine.getSeedManager().getComponent(),
+                    seaLevel, data);
+        };
+    }
+
+    private static int seaLevel(IrisDimension dimension) {
+        return dimension == null ? 0 : dimension.getFluidHeight();
+    }
+
+    abstract KList<IrisBlockData> blocks();
+
+    abstract double zoom();
+
+    int minThickness() {
+        return 1;
+    }
+
+    int maxThickness() {
+        return 1;
+    }
+
+    abstract boolean hasSlopeCondition();
+
+    /**
+     * How many blocks of this palette are stacked at the spot.
+     */
+    abstract int thickness(int blockX, int blockZ);
+
+    abstract double noise(int blockX, int blockZ, int depth);
+
+    /**
+     * What the preview simplifies about this palette, or null when it shows exactly what the world places.
+     */
+    String simplification() {
+        return null;
+    }
+
+    private abstract static class LayerPlacement extends BiomePalettePlacement {
+        protected final IrisBiomePaletteLayer layer;
+
+        private LayerPlacement(IrisBiomePaletteLayer layer, IrisData data) {
+            super(data);
+            this.layer = layer;
+        }
+
+        @Override
+        KList<IrisBlockData> blocks() {
+            return layer.getPalette();
+        }
+
+        @Override
+        double zoom() {
+            return layer.getZoom();
+        }
+
+        @Override
+        int minThickness() {
+            return layer.getMinHeight();
+        }
+
+        @Override
+        int maxThickness() {
+            return layer.getMaxHeight();
+        }
+
+        @Override
+        boolean hasSlopeCondition() {
+            return !layer.getSlopeCondition().isDefault();
+        }
+    }
+
+    private static final class SurfaceLayer extends LayerPlacement {
+        private final IrisBiome biome;
+        private final int index;
+        private final RNG random;
+
+        private SurfaceLayer(IrisBiome biome, int index, IrisBiomePaletteLayer layer, RNG random, IrisData data) {
+            super(layer, data);
+            this.biome = biome;
+            this.index = index;
+            this.random = random;
+        }
+
+        @Override
+        int thickness(int blockX, int blockZ) {
+            return biome.getLayerThickness(index, blockX, blockZ, random, data);
+        }
+
+        @Override
+        double noise(int blockX, int blockZ, int depth) {
+            return biome.getLayerNoise(index, blockX, blockZ, depth, random, data);
+        }
+    }
+
+    /**
+     * Sea and cave ceiling layers go through the older sampling path, which divides by the zoom twice and borrows
+     * its thickness noise from another list: a cave ceiling layer uses the surface layer at the same position's.
+     */
+    private static final class LegacyStackedLayer extends LayerPlacement {
+        private final RNG random;
+        private final CNG thicknessNoise;
+
+        private LegacyStackedLayer(IrisBiomePaletteLayer layer, IrisData data, RNG random, KList<CNG> thicknessNoises,
+                                   int index) {
+            super(layer, data);
+            this.random = random;
+            this.thicknessNoise = index < thicknessNoises.size() ? thicknessNoises.get(index) : null;
+        }
+
+        @Override
+        int thickness(int blockX, int blockZ) {
+            if (thicknessNoise == null) {
+                return 0;
+            }
+            double zoom = layer.getZoom();
+            return Math.max(0, thicknessNoise.fit(layer.getMinHeight(), layer.getMaxHeight(), blockX / zoom, blockZ / zoom));
+        }
+
+        @Override
+        double noise(int blockX, int blockZ, int depth) {
+            double zoom = layer.getZoom();
+            return layer.getLayerGenerator(random, data)
+                    .noise((blockX + depth) / zoom / zoom, depth / zoom, (blockZ - depth) / zoom / zoom);
+        }
+
+        @Override
+        String simplification() {
+            return thicknessNoise == null
+                    ? "The generator takes this layer's thickness from the surface layer at the same position, which doesn't exist, so it is never placed."
+                    : null;
+        }
+    }
+
+    /**
+     * Wall and slab blocks are picked one at a time with noise that also changes with height.
+     */
+    private static final class SingleBlocks extends LayerPlacement {
+        private final RNG random;
+        private final int sampleHeight;
+
+        private SingleBlocks(IrisBiomePaletteLayer layer, IrisData data, RNG random, int sampleHeight) {
+            super(layer, data);
+            this.random = random;
+            this.sampleHeight = sampleHeight;
+        }
+
+        @Override
+        int minThickness() {
+            return 1;
+        }
+
+        @Override
+        int maxThickness() {
+            return 1;
+        }
+
+        @Override
+        int thickness(int blockX, int blockZ) {
+            return 1;
+        }
+
+        @Override
+        double noise(int blockX, int blockZ, int depth) {
+            double zoom = layer.getZoom();
+            return layer.getLayerGenerator(random, data).noise(blockX / zoom, sampleHeight / zoom, blockZ / zoom);
+        }
+
+        @Override
+        String simplification() {
+            return "These blocks also change with height; the preview shows them at sea level (Y " + sampleHeight + ").";
+        }
+    }
+
+    /**
+     * A decorator places where its style noise stays under its chance, and its variance noise picks the block there.
+     * The generator seeds the variance noise from whichever block it decorates first, so the preview reuses that noise
+     * once the world has generated some decorations.
+     */
+    private static final class Decorations extends BiomePalettePlacement {
+        private final IrisDecorator decorator;
+        private final CNG placementNoise;
+        private final CNG blockNoise;
+        private final int sampleHeight;
+        private final boolean sharesSpotsWithOtherDecorators;
+
+        private Decorations(IrisBiome biome, IrisDecorator decorator, long componentSeed, int sampleHeight, IrisData data) {
+            super(data);
+            this.decorator = decorator;
+            RNG partRandom = new RNG(IrisEngineDecorator.partSeed(componentSeed, decorator.getPartOf()));
+            this.placementNoise = decorator.getGenerator(partRandom, data);
+            this.blockNoise = decorator.getVarianceGenerator(partRandom, data);
+            this.sampleHeight = sampleHeight;
+            this.sharesSpotsWithOtherDecorators = biome.getDecorators().stream()
+                    .anyMatch(other -> other != null && other != decorator && other.getPartOf() == decorator.getPartOf());
+        }
+
+        @Override
+        KList<IrisBlockData> blocks() {
+            return decorator.getPalette();
+        }
+
+        @Override
+        double zoom() {
+            return decorator.getStyle().getZoom();
+        }
+
+        @Override
+        boolean hasSlopeCondition() {
+            return !decorator.getSlopeCondition().isDefault();
+        }
+
+        @Override
+        int thickness(int blockX, int blockZ) {
+            double zoom = zoom();
+            return placementNoise.fitDouble(0D, 1D, blockX / zoom, blockZ / zoom) <= decorator.getChance() ? 1 : 0;
+        }
+
+        // The generator swaps X and Z when it picks the block.
+        @Override
+        double noise(int blockX, int blockZ, int depth) {
+            return blockNoise.noise(blockZ, sampleHeight, blockX);
+        }
+
+        @Override
+        String simplification() {
+            List<String> notes = new ArrayList<>();
+            String partNote = partNote(decorator.getPartOf());
+            if (partNote != null) {
+                notes.add(partNote);
+            }
+            if (sharesSpotsWithOtherDecorators) {
+                notes.add("Where other decorators of this biome could place too, the world picks one of them at random.");
+            }
+            if (placesTwoBlockTallPlants()) {
+                notes.add("Two block tall plants stand up on the map: their top half covers the block above them.");
+            }
+            if (decorator.isStacking()) {
+                notes.add("It stacks " + decorator.getStackMin() + "–" + decorator.getStackMax()
+                        + " blocks high; the preview shows the bottom block.");
+            }
+            if (blocks().size() > 1) {
+                notes.add("The block also changes with height; the preview picks it at sea level (Y " + sampleHeight + ").");
+            }
+            return notes.isEmpty() ? null : String.join(" ", notes);
+        }
+
+        // The generator places any two-part block as a bottom half with its top half above it.
+        private boolean placesTwoBlockTallPlants() {
+            return !decorator.isStacking() && blocks().stream().anyMatch(block -> block.getBlockData(data) instanceof Bisected);
+        }
+
+        private static String partNote(IrisDecorationPart part) {
+            return switch (part) {
+                case NONE -> null;
+                case SHORE_LINE -> "It only places along shore lines.";
+                case SEA_SURFACE -> "It only places on the sea surface.";
+                case SEA_FLOOR -> "It only places on the sea floor.";
+                case CEILING -> "It places on cave ceilings and the undersides of overhangs, not on the ground.";
+            };
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BiomeTint.java

@@ -16,10 +16,12 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.volmit.iris.util.reflect;
 
-public class ShadeFix {
-    public static void fix(Class<?> c) {
-        c.getCanonicalName();
-    }
+package com.volmit.iris.core.gui;
+
+enum BiomeTint {
+    GRASS,
+    FOLIAGE,
+    DRY_FOLIAGE,
+    WATER
 }

core/src/main/java/com/volmit/iris/core/gui/BiomeTintColors.java

@@ -0,0 +1,68 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import java.util.Locale;
+
+// The colours one Minecraft biome multiplies onto tinted blocks, as worked out by Biome#getGrassColor and friends.
+record BiomeTintColors(int grass, GrassColorModifier grassModifier, int foliage, int dryFoliage, int water) {
+    int colorAt(BiomeTint tint, int blockX, int blockZ) {
+        return switch (tint) {
+            case GRASS -> grassModifier.modify(blockX, blockZ, grass);
+            case FOLIAGE -> foliage;
+            case DRY_FOLIAGE -> dryFoliage;
+            case WATER -> water;
+        };
+    }
+
+    boolean variesByPosition() {
+        return grassModifier == GrassColorModifier.SWAMP;
+    }
+
+    enum GrassColorModifier {
+        NONE,
+        DARK_FOREST,
+        SWAMP;
+
+        private static final double SWAMP_NOISE_SCALE = 0.0225D;
+        private static final double SWAMP_WET_THRESHOLD = -0.1D;
+        private static final int SWAMP_WET_GRASS = 0x4C763C;
+        private static final int SWAMP_DRY_GRASS = 0x6A7039;
+        private static final int DARK_FOREST_SHIFT = 0x28340A;
+
+        static GrassColorModifier named(String name) {
+            return switch (name.toLowerCase(Locale.ROOT)) {
+                case "dark_forest" -> DARK_FOREST;
+                case "swamp" -> SWAMP;
+                default -> NONE;
+            };
+        }
+
+        int modify(int blockX, int blockZ, int baseColor) {
+            return switch (this) {
+                case NONE -> baseColor;
+                case DARK_FOREST -> ((baseColor & 0xFEFEFE) + DARK_FOREST_SHIFT) >> 1;
+                case SWAMP -> BiomeInfoNoise.at(blockX * SWAMP_NOISE_SCALE, blockZ * SWAMP_NOISE_SCALE) < SWAMP_WET_THRESHOLD
+                        ? SWAMP_WET_GRASS
+                        : SWAMP_DRY_GRASS;
+            };
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BiomeTintField.java

@@ -0,0 +1,138 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisBiomeCustom;
+import com.volmit.iris.util.collection.KList;
+import com.volmit.iris.util.math.RNG;
+import org.bukkit.block.Biome;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+// The tint Minecraft draws on each column of one Iris biome. Iris picks the Minecraft biome once per chunk
+// (see IrisBiomeActuator), and the client averages the colours of the columns around each block.
+final class BiomeTintField {
+    private static final int MINECRAFT_DEFAULT_BLEND_RADIUS = 2;
+    private static final int BLENDED_COLUMN_COUNT = (MINECRAFT_DEFAULT_BLEND_RADIUS * 2 + 1) * (MINECRAFT_DEFAULT_BLEND_RADIUS * 2 + 1);
+    private static final int BLENDED_TINT_CACHE_SIZE = 1 << 16;
+    private static final int CHUNK_COLORS_CACHE_SIZE = 1 << 10;
+
+    private final IrisBiome biome;
+    private final RNG biomeRandom;
+    private final MinecraftBiomeColors minecraftColors;
+    private final BiomeTintColors sameColorsEverywhere;
+    private final Map<IrisBiomeCustom, BiomeTintColors> colorsByCustomBiome = new ConcurrentHashMap<>();
+    private final BlendedTint[] blendedTintCache = new BlendedTint[BLENDED_TINT_CACHE_SIZE];
+    private final ChunkColors[] chunkColorsCache = new ChunkColors[CHUNK_COLORS_CACHE_SIZE];
+
+    BiomeTintField(IrisBiome biome, RNG biomeRandom, MinecraftBiomeColors minecraftColors) {
+        this.biome = biome;
+        this.biomeRandom = biomeRandom;
+        this.minecraftColors = minecraftColors;
+        BiomeTintColors onlyColors = onlyPossibleColors();
+        this.sameColorsEverywhere = onlyColors == null || onlyColors.variesByPosition() ? null : onlyColors;
+    }
+
+    int colorAt(BiomeTint tint, int blockX, int blockZ) {
+        if (sameColorsEverywhere != null) {
+            return sameColorsEverywhere.colorAt(tint, blockX, blockZ);
+        }
+        int cacheSlot = cacheSlot(blockX, blockZ, tint.ordinal(), BLENDED_TINT_CACHE_SIZE);
+        BlendedTint cached = blendedTintCache[cacheSlot];
+        if (cached != null && cached.x() == blockX && cached.z() == blockZ && cached.tint() == tint) {
+            return cached.color();
+        }
+        int color = blendedColor(tint, blockX, blockZ);
+        blendedTintCache[cacheSlot] = new BlendedTint(blockX, blockZ, tint, color);
+        return color;
+    }
+
+    // Minecraft's ClientLevel#calculateBlockTint at the default biome blend radius.
+    private int blendedColor(BiomeTint tint, int blockX, int blockZ) {
+        int red = 0;
+        int green = 0;
+        int blue = 0;
+        for (int x = blockX - MINECRAFT_DEFAULT_BLEND_RADIUS; x <= blockX + MINECRAFT_DEFAULT_BLEND_RADIUS; x++) {
+            for (int z = blockZ - MINECRAFT_DEFAULT_BLEND_RADIUS; z <= blockZ + MINECRAFT_DEFAULT_BLEND_RADIUS; z++) {
+                int color = chunkColors(x >> 4, z >> 4).colorAt(tint, x, z);
+                red += (color >>> 16) & 0xFF;
+                green += (color >>> 8) & 0xFF;
+                blue += color & 0xFF;
+            }
+        }
+        return (red / BLENDED_COLUMN_COUNT) << 16 | (green / BLENDED_COLUMN_COUNT) << 8 | (blue / BLENDED_COLUMN_COUNT);
+    }
+
+    private BiomeTintColors chunkColors(int chunkX, int chunkZ) {
+        int cacheSlot = cacheSlot(chunkX, chunkZ, 0, CHUNK_COLORS_CACHE_SIZE);
+        ChunkColors cached = chunkColorsCache[cacheSlot];
+        if (cached != null && cached.chunkX() == chunkX && cached.chunkZ() == chunkZ) {
+            return cached.colors();
+        }
+        BiomeTintColors colors = colorsForChunkAt(chunkX << 4, chunkZ << 4);
+        chunkColorsCache[cacheSlot] = new ChunkColors(chunkX, chunkZ, colors);
+        return colors;
+    }
+
+    private BiomeTintColors colorsForChunkAt(int originX, int originZ) {
+        if (biome.isCustom()) {
+            return customColors(biome.getCustomBiome(biomeRandom, originX, 0, originZ));
+        }
+        return vanillaColors(biome.getSkyBiome(biomeRandom, originX, 0, originZ));
+    }
+
+    // Follows the same choices as IrisBiome#getSkyBiome and #getCustomBiome, returning null when chunks can differ.
+    private BiomeTintColors onlyPossibleColors() {
+        if (biome.isCustom()) {
+            KList<IrisBiomeCustom> variants = biome.getCustomDerivitives();
+            return variants.size() == 1 ? customColors(variants.get(0)) : null;
+        }
+        KList<Biome> skyBiomes = biome.getBiomeSkyScatter();
+        if (!skyBiomes.isEmpty()) {
+            return skyBiomes.size() == 1 ? vanillaColors(skyBiomes.get(0)) : null;
+        }
+        KList<Biome> groundBiomes = biome.getBiomeScatter();
+        if (groundBiomes.isEmpty()) {
+            return vanillaColors(biome.getDerivative());
+        }
+        return groundBiomes.size() == 1 ? vanillaColors(groundBiomes.get(0)) : null;
+    }
+
+    private BiomeTintColors customColors(IrisBiomeCustom customBiome) {
+        return colorsByCustomBiome.computeIfAbsent(customBiome, minecraftColors::custom);
+    }
+
+    private BiomeTintColors vanillaColors(Biome vanillaBiome) {
+        return minecraftColors.vanilla(vanillaBiome.getKey());
+    }
+
+    private static int cacheSlot(int x, int z, int salt, int cacheSize) {
+        long hash = x * 0x9E3779B97F4A7C15L ^ z * 0xC2B2AE3D27D4EB4FL ^ salt * 0x165667B19E3779F9L;
+        return (int) ((hash ^ (hash >>> 29)) & (cacheSize - 1));
+    }
+
+    private record BlendedTint(int x, int z, BiomeTint tint, int color) {
+    }
+
+    private record ChunkColors(int chunkX, int chunkZ, BiomeTintColors colors) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BlockModel.java

@@ -0,0 +1,213 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.BlockTextures.BlockTexture;
+
+import java.util.ArrayList;
+import java.util.EnumSet;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.UnaryOperator;
+
+/**
+ * A block as the object viewer draws it: the textured faces of its model, in block units, already turned the way the
+ * blockstate faces.
+ *
+ * @param faces               every face of every box in the model
+ * @param coveredSides        the block's sides that a solid face fills completely, which hide whatever touches them
+ * @param hidesSameBlockSides whether the model fills the whole block, so like glass it hides the sides between two of
+ *                            the same blocks
+ */
+record BlockModel(List<Face> faces, Set<CubeFace> coveredSides, boolean hidesSameBlockSides) {
+    static final BlockModel EMPTY = new BlockModel(List.of(), Set.of(), false);
+    private static final int SIDE_CELLS = 16;
+    private static final double ON_SIDE_TOLERANCE = 1e-4D;
+
+    static BlockModel of(List<Face> faces) {
+        Set<CubeFace> coveredSides = EnumSet.noneOf(CubeFace.class);
+        boolean fillsEverySide = true;
+        for (CubeFace side : CubeFace.values()) {
+            if (sideIsFilled(faces, side, true)) {
+                coveredSides.add(side);
+            }
+            fillsEverySide &= sideIsFilled(faces, side, false);
+        }
+        return new BlockModel(List.copyOf(faces), Set.copyOf(coveredSides), fillsEverySide);
+    }
+
+    static BlockModel solidColor(int color) {
+        BlockTexture texture = BlockTexture.solid(color);
+        List<Face> faces = new ArrayList<>();
+        for (CubeFace side : CubeFace.values()) {
+            faces.add(Face.boxSide(Vec3.ZERO, new Vec3(1D, 1D, 1D), side, texture, side));
+        }
+        return of(faces);
+    }
+
+    boolean isEmpty() {
+        return faces.isEmpty();
+    }
+
+    BlockModel withTextures(UnaryOperator<BlockTexture> change) {
+        Map<BlockTexture, BlockTexture> changed = new IdentityHashMap<>();
+        List<Face> changedFaces = new ArrayList<>(faces.size());
+        for (Face face : faces) {
+            changedFaces.add(face.withTexture(changed.computeIfAbsent(face.texture(), change)));
+        }
+        return new BlockModel(List.copyOf(changedFaces), coveredSides, hidesSameBlockSides);
+    }
+
+    // The side is split into a grid, and every cell has to lie under a face pressed flat against it.
+    private static boolean sideIsFilled(List<Face> faces, CubeFace side, boolean onlySolidFaces) {
+        boolean[] filled = new boolean[SIDE_CELLS * SIDE_CELLS];
+        for (Face face : faces) {
+            if (face.liesOn(side) && (!onlySolidFaces || face.texture().isFullyOpaque())) {
+                face.fillCells(side, filled, SIDE_CELLS);
+            }
+        }
+        for (boolean cell : filled) {
+            if (!cell) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * A parallelogram from {@code origin} along {@code edgeU} and {@code edgeV}. The texture point at the origin and
+     * how it moves along each edge are given as fractions of the texture.
+     *
+     * @param normal   the way the face looks out; it is hidden when seen from behind
+     * @param cullFace the block side whose neighbour hides this face when it covers that side, or null
+     */
+    record Face(Vec3 origin, Vec3 edgeU, Vec3 edgeV, Vec3 normal, BlockTexture texture, TextureMapping mapping,
+                double shade, CubeFace cullFace) {
+
+        // Laid out as seen from outside: u to the right and v downwards, matching Minecraft's UVs for a whole texture.
+        static Face boxSide(Vec3 from, Vec3 to, CubeFace side, BlockTexture texture, CubeFace cullFace) {
+            Vec3[] corners = BoxCorners.of(from, to, side);
+            return new Face(corners[0], corners[3].minus(corners[0]), corners[1].minus(corners[0]), side.direction(),
+                    texture, TextureMapping.WHOLE, side.shade(), cullFace);
+        }
+
+        Face withTexture(BlockTexture changedTexture) {
+            return new Face(origin, edgeU, edgeV, normal, changedTexture, mapping, shade, cullFace);
+        }
+
+        Face transformed(Transform transform) {
+            Vec3 turnedNormal = transform.direction(normal);
+            double length = Math.sqrt(turnedNormal.x() * turnedNormal.x() + turnedNormal.y() * turnedNormal.y() + turnedNormal.z() * turnedNormal.z());
+            return new Face(transform.point(origin), transform.direction(edgeU), transform.direction(edgeV),
+                    length == 0D ? turnedNormal : turnedNormal.times(1D / length), texture, mapping, shade,
+                    cullFace == null ? null : CubeFace.nearest(transform.direction(cullFace.direction())));
+        }
+
+        Face withCullFace(CubeFace side) {
+            return new Face(origin, edgeU, edgeV, normal, texture, mapping, shade, side);
+        }
+
+        Face withShade(double changedShade) {
+            return new Face(origin, edgeU, edgeV, normal, texture, mapping, changedShade, cullFace);
+        }
+
+        private boolean liesOn(CubeFace side) {
+            int axis = side.axis();
+            double plane = side.pointsPositive() ? 1D : 0D;
+            return CubeFace.nearest(normal) == side
+                    && Math.abs(normal.component(axis)) > 1D - ON_SIDE_TOLERANCE
+                    && Math.abs(origin.component(axis) - plane) < ON_SIDE_TOLERANCE
+                    && Math.abs(edgeU.component(axis)) < ON_SIDE_TOLERANCE
+                    && Math.abs(edgeV.component(axis)) < ON_SIDE_TOLERANCE;
+        }
+
+        private void fillCells(CubeFace side, boolean[] filled, int cells) {
+            int firstAxis = side.axis() == 0 ? 1 : 0;
+            int secondAxis = side.axis() == 2 ? 1 : 2;
+            double[] firstRange = range(firstAxis);
+            double[] secondRange = range(secondAxis);
+            for (int first = 0; first < cells; first++) {
+                double firstCenter = (first + 0.5D) / cells;
+                if (firstCenter < firstRange[0] || firstCenter > firstRange[1]) {
+                    continue;
+                }
+                for (int second = 0; second < cells; second++) {
+                    double secondCenter = (second + 0.5D) / cells;
+                    if (secondCenter >= secondRange[0] && secondCenter <= secondRange[1]) {
+                        filled[first * cells + second] = true;
+                    }
+                }
+            }
+        }
+
+        private double[] range(int axis) {
+            double start = origin.component(axis);
+            double alongU = edgeU.component(axis);
+            double alongV = edgeV.component(axis);
+            double low = start + Math.min(0D, alongU) + Math.min(0D, alongV);
+            double high = start + Math.max(0D, alongU) + Math.max(0D, alongV);
+            return new double[]{low, high};
+        }
+    }
+
+    /**
+     * Where a face's corner sits in its texture and how the texture point moves along the face's two edges, all as
+     * fractions of the texture's width and height.
+     */
+    record TextureMapping(double u, double v, double uAlongU, double vAlongU, double uAlongV, double vAlongV) {
+        static final TextureMapping WHOLE = new TextureMapping(0D, 0D, 1D, 0D, 0D, 1D);
+    }
+
+    /**
+     * A box side's corners in Minecraft's order: top left, bottom left, bottom right and top right, as seen from
+     * outside the box.
+     */
+    static final class BoxCorners {
+        private BoxCorners() {
+        }
+
+        static Vec3[] of(Vec3 from, Vec3 to, CubeFace side) {
+            double minX = from.x();
+            double minY = from.y();
+            double minZ = from.z();
+            double maxX = to.x();
+            double maxY = to.y();
+            double maxZ = to.z();
+            return switch (side) {
+                case DOWN -> corners(minX, minY, maxZ, minX, minY, minZ, maxX, minY, minZ, maxX, minY, maxZ);
+                case UP -> corners(minX, maxY, minZ, minX, maxY, maxZ, maxX, maxY, maxZ, maxX, maxY, minZ);
+                case NORTH -> corners(maxX, maxY, minZ, maxX, minY, minZ, minX, minY, minZ, minX, maxY, minZ);
+                case SOUTH -> corners(minX, maxY, maxZ, minX, minY, maxZ, maxX, minY, maxZ, maxX, maxY, maxZ);
+                case WEST -> corners(minX, maxY, minZ, minX, minY, minZ, minX, minY, maxZ, minX, maxY, maxZ);
+                case EAST -> corners(maxX, maxY, maxZ, maxX, minY, maxZ, maxX, minY, minZ, maxX, maxY, minZ);
+            };
+        }
+
+        private static Vec3[] corners(double... coordinates) {
+            Vec3[] corners = new Vec3[4];
+            for (int corner = 0; corner < 4; corner++) {
+                corners[corner] = new Vec3(coordinates[corner * 3], coordinates[corner * 3 + 1], coordinates[corner * 3 + 2]);
+            }
+            return corners;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BlockModelBuilder.java

@@ -0,0 +1,351 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.volmit.iris.core.gui.BlockModel.BoxCorners;
+import com.volmit.iris.core.gui.BlockModel.Face;
+import com.volmit.iris.core.gui.BlockModel.TextureMapping;
+import com.volmit.iris.core.gui.BlockTextures.BlockStateId;
+import com.volmit.iris.core.gui.BlockTextures.BlockTexture;
+import com.volmit.iris.core.gui.BlockTextures.ModelDefinition;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * Reads a block's look the way Minecraft does: every model part the blockstate picks, every box with its own texture
+ * and UVs, tilted boxes, the blockstate's turn with or without locked textures, and which faces a neighbour hides.
+ */
+final class BlockModelBuilder {
+    private static final double MODEL_UNITS = 16D;
+    private static final double BLOCK_CENTER = 0.5D;
+    private static final int QUARTER_TURN = 90;
+
+    private final BlockTextures textures;
+    private final EntityBlockShapes entityShapes;
+
+    BlockModelBuilder(BlockTextures textures) {
+        this.textures = textures;
+        this.entityShapes = new EntityBlockShapes(textures);
+    }
+
+    Optional<BlockModel> build(String blockState) {
+        try {
+            BlockStateId state = BlockStateId.parse(blockState);
+            List<JsonObject> placements = placementsOf(state);
+            if (placements == null) {
+                return Optional.empty();
+            }
+            List<Face> faces = new ArrayList<>();
+            for (JsonObject placement : placements) {
+                faces.addAll(placedFaces(state, placement));
+            }
+            faces.addAll(entityShapes.facesAddedTo(state));
+            return Optional.of(BlockModel.of(faces));
+        } catch (IOException | RuntimeException error) {
+            return Optional.empty();
+        }
+    }
+
+    /**
+     * A box with Minecraft's default UVs on each side, for shapes the game draws in code.
+     */
+    static List<Face> box(Vec3 fromPixels, Vec3 toPixels, BlockTexture texture, boolean culledBySides) {
+        List<Face> faces = new ArrayList<>();
+        for (CubeFace side : CubeFace.values()) {
+            FaceUv uv = FaceUv.byDefault(side, fromPixels, toPixels);
+            Face face = boxFace(fromPixels, toPixels, side, texture, uv).withShade(side.shade());
+            faces.add(culledBySides ? face.withCullFace(side) : face);
+        }
+        return faces;
+    }
+
+    // A variant names one model; a multipart blockstate, like a fence's, adds a part for every condition that holds.
+    private List<JsonObject> placementsOf(BlockStateId state) throws IOException {
+        JsonObject definition = textures.readJson(BlockTextures.assetPath(state.namespace() + ":" + state.name(), "blockstates", ".json"));
+        if (definition == null) {
+            return null;
+        }
+        List<JsonObject> placements = new ArrayList<>();
+        if (definition.has("variants")) {
+            for (Map.Entry<String, JsonElement> variant : definition.getAsJsonObject("variants").entrySet()) {
+                if (BlockTextures.variantMatches(variant.getKey(), state.properties())) {
+                    addPlacement(placements, variant.getValue());
+                    break;
+                }
+            }
+        }
+        if (definition.has("multipart")) {
+            for (JsonElement part : definition.getAsJsonArray("multipart")) {
+                JsonObject rule = part.getAsJsonObject();
+                if (!rule.has("when") || BlockTextures.conditionMatches(rule.getAsJsonObject("when"), state.properties())) {
+                    addPlacement(placements, rule.get("apply"));
+                }
+            }
+        }
+        return placements;
+    }
+
+    private static void addPlacement(List<JsonObject> placements, JsonElement models) {
+        JsonObject first = BlockTextures.firstModel(models);
+        if (first != null && first.has("model")) {
+            placements.add(first);
+        }
+    }
+
+    private List<Face> placedFaces(BlockStateId state, JsonObject placement) throws IOException {
+        ModelDefinition model = textures.readModel(placement.get("model").getAsString());
+        if (model.elements() == null) {
+            return entityShapes.facesOf(state, model);
+        }
+        BlockRotation rotation = BlockRotation.of(placement);
+        List<Face> faces = new ArrayList<>();
+        for (JsonElement element : model.elements()) {
+            addElementFaces(faces, state, model, element.getAsJsonObject(), rotation);
+        }
+        return faces;
+    }
+
+    private void addElementFaces(List<Face> faces, BlockStateId state, ModelDefinition model, JsonObject element, BlockRotation rotation) {
+        JsonObject elementFaces = element.getAsJsonObject("faces");
+        if (elementFaces == null) {
+            return;
+        }
+        Vec3 from = vector(element.getAsJsonArray("from"));
+        Vec3 to = vector(element.getAsJsonArray("to"));
+        Transform tilt = tiltOf(element);
+        boolean shaded = !element.has("shade") || element.get("shade").getAsBoolean();
+        CubeFace shadeSide = element.has("shade_direction_override")
+                ? CubeFace.named(element.get("shade_direction_override").getAsString()) : null;
+        for (Map.Entry<String, JsonElement> entry : elementFaces.entrySet()) {
+            CubeFace side = CubeFace.named(entry.getKey());
+            JsonObject faceJson = entry.getValue().getAsJsonObject();
+            if (side == null || !faceJson.has("texture")) {
+                continue;
+            }
+            String textureName = BlockTextures.dereference(faceJson.get("texture").getAsString(), model.textures());
+            if (textureName == null) {
+                continue;
+            }
+            Optional<BlockTexture> texture = textures.faceTexture(state, textureName, BlockTextures.tintIndexOf(faceJson));
+            if (texture.isEmpty()) {
+                continue;
+            }
+            FaceUv uv = FaceUv.of(faceJson, side, from, to);
+            if (rotation.locksTextures()) {
+                uv = uv.lockedTo(side, rotation);
+            }
+            Face face = boxFace(from, to, side, texture.get(), uv).transformed(tilt);
+            if (faceJson.has("cullface")) {
+                face = face.withCullFace(CubeFace.named(faceJson.get("cullface").getAsString()));
+            }
+            face = face.transformed(rotation.transform());
+            faces.add(face.withShade(shadeOf(face, shaded, shadeSide, rotation)));
+        }
+    }
+
+    private static Face boxFace(Vec3 fromPixels, Vec3 toPixels, CubeFace side, BlockTexture texture, FaceUv uv) {
+        Vec3[] corners = BoxCorners.of(fromPixels.times(1D / MODEL_UNITS), toPixels.times(1D / MODEL_UNITS), side);
+        return new Face(corners[0], corners[3].minus(corners[0]), corners[1].minus(corners[0]), side.direction(),
+                texture, uv.mapping(), side.shade(), null);
+    }
+
+    private static double shadeOf(Face face, boolean shaded, CubeFace shadeSide, BlockRotation rotation) {
+        if (!shaded) {
+            return CubeFace.UP.shade();
+        }
+        if (shadeSide != null) {
+            return CubeFace.nearest(rotation.transform().direction(shadeSide.direction())).shade();
+        }
+        return CubeFace.nearest(face.normal()).shade();
+    }
+
+    // A box can be tilted around a point, on one axis or, since 1.21.?, on all three; rescaling stretches a tilted
+    // plant back to the full block width.
+    private static Transform tiltOf(JsonObject element) {
+        if (!element.has("rotation")) {
+            return Transform.IDENTITY;
+        }
+        JsonObject rotation = element.getAsJsonObject("rotation");
+        Vec3 origin = rotation.has("origin") ? vector(rotation.getAsJsonArray("origin")).times(1D / MODEL_UNITS) : new Vec3(BLOCK_CENTER, BLOCK_CENTER, BLOCK_CENTER);
+        Transform around = Transform.IDENTITY.translate(origin.x(), origin.y(), origin.z());
+        Transform back = Transform.IDENTITY.translate(-origin.x(), -origin.y(), -origin.z());
+        if (!rotation.has("axis")) {
+            return around
+                    .rotateX(numberOr(rotation, "x", 0D))
+                    .rotateY(numberOr(rotation, "y", 0D))
+                    .rotateZ(numberOr(rotation, "z", 0D))
+                    .then(back);
+        }
+        String axis = rotation.get("axis").getAsString();
+        double angle = numberOr(rotation, "angle", 0D);
+        boolean rescale = rotation.has("rescale") && rotation.get("rescale").getAsBoolean();
+        double stretch = rescale ? 1D / Math.cos(Math.toRadians(angle)) : 1D;
+        Transform stretched = around.scale(axis.equals("x") ? 1D : stretch, axis.equals("y") ? 1D : stretch, axis.equals("z") ? 1D : stretch);
+        Transform tilted = switch (axis) {
+            case "x" -> stretched.rotateX(angle);
+            case "y" -> stretched.rotateY(angle);
+            default -> stretched.rotateZ(angle);
+        };
+        return tilted.then(back);
+    }
+
+    private static double numberOr(JsonObject object, String key, double fallback) {
+        return object.has(key) ? object.get(key).getAsDouble() : fallback;
+    }
+
+    private static Vec3 vector(JsonArray values) {
+        return new Vec3(values.get(0).getAsDouble(), values.get(1).getAsDouble(), values.get(2).getAsDouble());
+    }
+
+    /**
+     * How a blockstate turns its model: around the x axis first, then the y axis, both in quarter turns against the
+     * right-hand rule. With uvlock the textures stay put while the shape turns.
+     */
+    private record BlockRotation(int x, int y, boolean uvlock) {
+        static BlockRotation of(JsonObject placement) {
+            int x = placement.has("x") ? Math.floorMod(placement.get("x").getAsInt(), 360) : 0;
+            int y = placement.has("y") ? Math.floorMod(placement.get("y").getAsInt(), 360) : 0;
+            return new BlockRotation(x, y, placement.has("uvlock") && placement.get("uvlock").getAsBoolean());
+        }
+
+        boolean locksTextures() {
+            return uvlock && (x != 0 || y != 0);
+        }
+
+        Transform transform() {
+            return Transform.IDENTITY
+                    .translate(BLOCK_CENTER, BLOCK_CENTER, BLOCK_CENTER)
+                    .then(turn())
+                    .translate(-BLOCK_CENTER, -BLOCK_CENTER, -BLOCK_CENTER);
+        }
+
+        Transform turn() {
+            return Transform.IDENTITY.rotateY(-y).rotateX(-x);
+        }
+
+        Transform inverseTurn() {
+            return Transform.IDENTITY.rotateX(x).rotateY(y);
+        }
+    }
+
+    /**
+     * A face's corner UVs in model pixels and the quarter turn of the texture on it.
+     */
+    private record FaceUv(double u1, double v1, double u2, double v2, int rotation) {
+        static FaceUv of(JsonObject face, CubeFace side, Vec3 from, Vec3 to) {
+            int rotation = face.has("rotation") ? Math.floorMod(face.get("rotation").getAsInt(), 360) : 0;
+            if (!face.has("uv")) {
+                return byDefault(side, from, to).withRotation(rotation);
+            }
+            JsonArray uv = face.getAsJsonArray("uv");
+            return new FaceUv(uv.get(0).getAsDouble(), uv.get(1).getAsDouble(), uv.get(2).getAsDouble(), uv.get(3).getAsDouble(), rotation);
+        }
+
+        // The part of the texture the face would cover if the texture were laid over the whole block side.
+        static FaceUv byDefault(CubeFace side, Vec3 from, Vec3 to) {
+            double full = MODEL_UNITS;
+            return switch (side) {
+                case DOWN -> new FaceUv(from.x(), full - to.z(), to.x(), full - from.z(), 0);
+                case UP -> new FaceUv(from.x(), from.z(), to.x(), to.z(), 0);
+                case NORTH -> new FaceUv(full - to.x(), full - to.y(), full - from.x(), full - from.y(), 0);
+                case SOUTH -> new FaceUv(from.x(), full - to.y(), to.x(), full - from.y(), 0);
+                case WEST -> new FaceUv(from.z(), full - to.y(), to.z(), full - from.y(), 0);
+                case EAST -> new FaceUv(full - to.z(), full - to.y(), full - from.z(), full - from.y(), 0);
+            };
+        }
+
+        FaceUv withRotation(int changedRotation) {
+            return new FaceUv(u1, v1, u2, v2, changedRotation);
+        }
+
+        // Each corner takes the UV a quarter turn further along for every quarter turn of the texture.
+        TextureMapping mapping() {
+            double[] origin = cornerUv(0);
+            double[] alongU = cornerUv(3);
+            double[] alongV = cornerUv(1);
+            return new TextureMapping(origin[0] / MODEL_UNITS, origin[1] / MODEL_UNITS,
+                    (alongU[0] - origin[0]) / MODEL_UNITS, (alongU[1] - origin[1]) / MODEL_UNITS,
+                    (alongV[0] - origin[0]) / MODEL_UNITS, (alongV[1] - origin[1]) / MODEL_UNITS);
+        }
+
+        private double[] cornerUv(int corner) {
+            return switch ((corner + rotation / QUARTER_TURN) % 4) {
+                case 0 -> new double[]{u1, v1};
+                case 1 -> new double[]{u1, v2};
+                case 2 -> new double[]{u2, v2};
+                default -> new double[]{u2, v1};
+            };
+        }
+
+        /**
+         * Minecraft's uvlock: the UVs are carried through the reverse of the blockstate's turn, so the texture keeps
+         * its place in the world while the face moves to another side.
+         */
+        FaceUv lockedTo(CubeFace side, BlockRotation blockRotation) {
+            CubeFace turnedSide = CubeFace.nearest(blockRotation.turn().direction(side.direction()));
+            Transform uvTurn = Transform.IDENTITY
+                    .translate(BLOCK_CENTER, BLOCK_CENTER, BLOCK_CENTER)
+                    .then(faceFromWorld(side))
+                    .then(blockRotation.inverseTurn())
+                    .then(worldFromFace(turnedSide))
+                    .translate(-BLOCK_CENTER, -BLOCK_CENTER, -BLOCK_CENTER);
+            Vec3 first = uvTurn.point(new Vec3(u1 / MODEL_UNITS, v1 / MODEL_UNITS, 0D)).times(MODEL_UNITS);
+            Vec3 second = uvTurn.point(new Vec3(u2 / MODEL_UNITS, v2 / MODEL_UNITS, 0D)).times(MODEL_UNITS);
+            boolean keepsUOrder = Math.signum(u2 - u1) == Math.signum(second.x() - first.x());
+            boolean keepsVOrder = Math.signum(v2 - v1) == Math.signum(second.y() - first.y());
+            Vec3 textureRight = uvTurn.direction(new Vec3(Math.cos(Math.toRadians(rotation)), Math.sin(Math.toRadians(rotation)), 0D));
+            long quarterTurns = Math.round(Math.toDegrees(Math.atan2(textureRight.y(), textureRight.x())) / QUARTER_TURN);
+            return new FaceUv(
+                    keepsUOrder ? first.x() : second.x(), keepsVOrder ? first.y() : second.y(),
+                    keepsUOrder ? second.x() : first.x(), keepsVOrder ? second.y() : first.y(),
+                    (int) Math.floorMod(-quarterTurns * QUARTER_TURN, 360L));
+        }
+
+        // Minecraft lays every side's texture out as if it were the south side, turned into place.
+        private static Transform worldFromFace(CubeFace side) {
+            return switch (side) {
+                case SOUTH -> Transform.IDENTITY;
+                case EAST -> Transform.IDENTITY.rotateY(90D);
+                case WEST -> Transform.IDENTITY.rotateY(-90D);
+                case NORTH -> Transform.IDENTITY.rotateY(180D);
+                case UP -> Transform.IDENTITY.rotateX(-90D);
+                case DOWN -> Transform.IDENTITY.rotateX(90D);
+            };
+        }
+
+        private static Transform faceFromWorld(CubeFace side) {
+            return switch (side) {
+                case SOUTH -> Transform.IDENTITY;
+                case EAST -> Transform.IDENTITY.rotateY(-90D);
+                case WEST -> Transform.IDENTITY.rotateY(90D);
+                case NORTH -> Transform.IDENTITY.rotateY(180D);
+                case UP -> Transform.IDENTITY.rotateX(90D);
+                case DOWN -> Transform.IDENTITY.rotateX(-90D);
+            };
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BlockPreviewColors.java

@@ -0,0 +1,101 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import org.bukkit.block.data.BlockData;
+
+import java.awt.Color;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+final class BlockPreviewColors {
+    private static final Method MAP_COLOR_METHOD = findMapColorMethod();
+    private static final double[] MAP_SHADES = {1D, 0.86D, 0.71D, 0.53D};
+    private static final int NO_MAP_COLOR = 0;
+
+    private BlockPreviewColors() {
+    }
+
+    static Map<String, Integer> colorsByBlock(List<BlockData> blocks) {
+        Map<String, Integer> colors = new HashMap<>();
+        List<Integer> usedColors = new ArrayList<>();
+        for (BlockData block : blocks) {
+            String key = block.getAsString(true);
+            if (colors.containsKey(key)) {
+                continue;
+            }
+            int baseColor = baseColor(block);
+            int color = firstUnusedShade(baseColor, usedColors);
+            usedColors.add(color);
+            colors.put(key, color);
+        }
+        return colors;
+    }
+
+    // Blocks that share a map colour, like sand and sandstone, get darker shades the way Minecraft maps shade them.
+    private static int firstUnusedShade(int baseColor, List<Integer> usedColors) {
+        for (double shade : MAP_SHADES) {
+            int shaded = shade(baseColor, shade);
+            if (!usedColors.contains(shaded)) {
+                return shaded;
+            }
+        }
+        return baseColor;
+    }
+
+    private static int baseColor(BlockData block) {
+        int mapColor = mapColor(block);
+        return mapColor == NO_MAP_COLOR ? colorFromName(block.getMaterial().getKey().getKey()) : mapColor;
+    }
+
+    private static int mapColor(BlockData block) {
+        if (MAP_COLOR_METHOD == null) {
+            return NO_MAP_COLOR;
+        }
+        try {
+            return ((org.bukkit.Color) MAP_COLOR_METHOD.invoke(block)).asRGB();
+        } catch (ReflectiveOperationException | RuntimeException error) {
+            return NO_MAP_COLOR;
+        }
+    }
+
+    private static int colorFromName(String name) {
+        float hue = (name.hashCode() & 0xFFFF) / (float) 0xFFFF;
+        return Color.HSBtoRGB(hue, 0.45F, 0.75F) & 0xFFFFFF;
+    }
+
+    static int shade(int color, double shade) {
+        int red = (int) Math.min(255, ((color >>> 16) & 0xFF) * shade);
+        int green = (int) Math.min(255, ((color >>> 8) & 0xFF) * shade);
+        int blue = (int) Math.min(255, (color & 0xFF) * shade);
+        return (red << 16) | (green << 8) | blue;
+    }
+
+    // Iris compiles against the 1.20.1 API, which predates BlockData#getMapColor.
+    private static Method findMapColorMethod() {
+        try {
+            return BlockData.class.getMethod("getMapColor");
+        } catch (NoSuchMethodException error) {
+            return null;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/BlockTextures.java

@@ -0,0 +1,603 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import org.bukkit.block.data.Bisected;
+import org.bukkit.block.data.BlockData;
+
+import java.awt.Graphics2D;
+import java.awt.image.BufferedImage;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.zip.ZipFile;
+
+final class BlockTextures {
+    private static final String DEFAULT_NAMESPACE = "minecraft";
+    private static final int MAX_MODEL_PARENTS = 16;
+    private static final int MAX_TEXTURE_REFERENCES = 16;
+    static final int NO_TINT_INDEX = -1;
+    private static final Object SHARED_LOCK = new Object();
+    private static CompletableFuture<BlockTextures> shared;
+
+    private final ZipFile clientJar;
+    private final MinecraftBiomeColors biomeColors;
+    private final Map<String, Optional<ResolvedTexture>> resolvedTextures = new ConcurrentHashMap<>();
+    private final Map<String, Optional<BlockModel>> resolvedModels = new ConcurrentHashMap<>();
+    private final Map<String, Optional<BlockTexture>> faceTextures = new ConcurrentHashMap<>();
+    private final BlockModelBuilder modelBuilder = new BlockModelBuilder(this);
+
+    private BlockTextures(ZipFile clientJar, MinecraftBiomeColors biomeColors) {
+        this.clientJar = clientJar;
+        this.biomeColors = biomeColors;
+    }
+
+    static CompletableFuture<BlockTextures> shared() {
+        synchronized (SHARED_LOCK) {
+            if (shared == null || shared.isCompletedExceptionally()) {
+                shared = MinecraftClientJar.open().thenApply(BlockTextures::load);
+            }
+            return shared;
+        }
+    }
+
+    private static BlockTextures load(ZipFile clientJar) {
+        try {
+            return new BlockTextures(clientJar, MinecraftBiomeColors.load(clientJar));
+        } catch (IOException error) {
+            throw new IllegalStateException("Could not read Minecraft's biome colour maps", error);
+        }
+    }
+
+    MinecraftBiomeColors biomeColors() {
+        return biomeColors;
+    }
+
+    /**
+     * What the block looks like from above. Plants and other side-on sprites become their average colour, because
+     * their sprite would read as stripes across a stack of ground blocks.
+     */
+    Optional<BlockTexture> topTexture(BlockData block) {
+        return resolve(block).map(resolved -> resolved.isSideOnSprite() ? resolved.texture().flattened() : resolved.texture());
+    }
+
+    /**
+     * Like {@link #topTexture}, but plants keep their sprite, so single decorations on the ground stay recognisable.
+     * Two block tall plants give their bottom half, the part standing on the ground.
+     */
+    Optional<BlockTexture> iconTexture(BlockData block) {
+        BlockData standing = block instanceof Bisected ? withHalf(block, Bisected.Half.BOTTOM) : block;
+        return resolve(standing).map(ResolvedTexture::texture);
+    }
+
+    /**
+     * The sprite of a two block tall plant's top half, or nothing for any other block.
+     */
+    Optional<BlockTexture> upperHalfIcon(BlockData block) {
+        if (!(block instanceof Bisected)) {
+            return Optional.empty();
+        }
+        return resolve(withHalf(block, Bisected.Half.TOP)).filter(ResolvedTexture::isSideOnSprite).map(ResolvedTexture::texture);
+    }
+
+    /**
+     * What the block looks like from every side, for drawing it in 3D.
+     */
+    Optional<BlockModel> model(BlockData block) {
+        return resolvedModels.computeIfAbsent(block.getAsString(false), modelBuilder::build);
+    }
+
+    private static BlockData withHalf(BlockData block, Bisected.Half half) {
+        BlockData copy = block.clone();
+        ((Bisected) copy).setHalf(half);
+        return copy;
+    }
+
+    // Blockstate files match on every property, so defaults the pack left out have to be spelled out too.
+    private Optional<ResolvedTexture> resolve(BlockData block) {
+        return resolvedTextures.computeIfAbsent(block.getAsString(false), this::resolveTopTexture);
+    }
+
+    private Optional<ResolvedTexture> resolveTopTexture(String blockState) {
+        try {
+            BlockStateId state = BlockStateId.parse(blockState);
+            JsonObject variant = variantOf(state);
+            if (variant == null || !variant.has("model")) {
+                return Optional.empty();
+            }
+            ModelFace face = readModel(variant.get("model").getAsString()).visibleFace(faceSeenFromAbove(variant));
+            if (face == null) {
+                return Optional.empty();
+            }
+            return readTexture(state, face).map(texture -> new ResolvedTexture(texture, face.isSideOnSprite()));
+        } catch (IOException | RuntimeException error) {
+            return Optional.empty();
+        }
+    }
+
+    private JsonObject variantOf(BlockStateId state) throws IOException {
+        JsonObject definition = readJson(assetPath(state.namespace() + ":" + state.name(), "blockstates", ".json"));
+        return definition == null ? null : pickVariant(definition, state.properties());
+    }
+
+    private static int rotationOf(JsonObject variant, String axis) {
+        return variant.has(axis) ? Math.floorMod(variant.get(axis).getAsInt(), 360) : 0;
+    }
+
+    /**
+     * One model face's texture with the block's tint, shared by every block state that uses it.
+     */
+    Optional<BlockTexture> faceTexture(BlockStateId state, String texture, int tintIndex) {
+        int fixedTint = MinecraftBlockTints.fixedTint(state.name(), state.properties(), tintIndex);
+        BiomeTint biomeTint = MinecraftBlockTints.biomeTint(state.name(), tintIndex).orElse(null);
+        return faceTextures.computeIfAbsent(texture + "|" + fixedTint + "|" + biomeTint, key -> {
+            try {
+                return readTexture(state, new ModelFace(List.of(texture), tintIndex, false));
+            } catch (IOException | RuntimeException error) {
+                return Optional.empty();
+            }
+        });
+    }
+
+    /**
+     * A texture drawn on a block entity, like a chest, whole and tinted with a fixed colour.
+     */
+    Optional<BlockTexture> entityTexture(String texture, int tint) {
+        return faceTextures.computeIfAbsent(texture + "|entity|" + tint, key -> {
+            try {
+                BufferedImage image = readImage(assetPath(texture, "textures", ".png"));
+                return image == null ? Optional.empty() : Optional.of(BlockTexture.fromWholeImage(image, tint));
+            } catch (IOException | RuntimeException error) {
+                return Optional.empty();
+            }
+        });
+    }
+
+    private Optional<BlockTexture> readTexture(BlockStateId state, ModelFace face) throws IOException {
+        BufferedImage image = readLayeredImage(face.textures());
+        if (image == null) {
+            return Optional.empty();
+        }
+        try {
+            return Optional.of(BlockTexture.fromImage(
+                    image,
+                    MinecraftBlockTints.fixedTint(state.name(), state.properties(), face.tintIndex()),
+                    MinecraftBlockTints.biomeTint(state.name(), face.tintIndex()).orElse(null)
+            ));
+        } catch (IllegalArgumentException invisibleTexture) {
+            return Optional.empty();
+        }
+    }
+
+    // A block rotated on its x axis, like a sideways log, shows a side face on top. Blockstates turn the model
+    // against the right-hand rule, so 90 degrees brings the south side up.
+    private static String faceSeenFromAbove(JsonObject variant) {
+        return switch (rotationOf(variant, "x")) {
+            case 90 -> "south";
+            case 270 -> "north";
+            case 180 -> "down";
+            default -> "up";
+        };
+    }
+
+    ModelDefinition readModel(String modelReference) throws IOException {
+        Map<String, String> textures = new HashMap<>();
+        JsonArray elements = null;
+        String current = modelReference;
+        for (int depth = 0; current != null && depth < MAX_MODEL_PARENTS; depth++) {
+            JsonObject model = readJson(assetPath(current, "models", ".json"));
+            if (model == null) {
+                break;
+            }
+            if (model.has("textures")) {
+                for (Map.Entry<String, JsonElement> texture : model.getAsJsonObject("textures").entrySet()) {
+                    textures.putIfAbsent(texture.getKey(), spriteName(texture.getValue()));
+                }
+            }
+            if (elements == null && model.has("elements")) {
+                elements = model.getAsJsonArray("elements");
+            }
+            current = model.has("parent") ? model.get("parent").getAsString() : null;
+        }
+        return new ModelDefinition(textures, elements);
+    }
+
+    // Since 1.21.? a texture can also be an object naming its sprite, like glass's {"sprite": ..., "force_translucent": true}.
+    private static String spriteName(JsonElement texture) {
+        return texture.isJsonObject() ? texture.getAsJsonObject().get("sprite").getAsString() : texture.getAsString();
+    }
+
+    // Some plants draw a second sprite over the first, like the glowing fireflies on a firefly bush.
+    private static List<String> spriteLayers(JsonArray elements, Map<String, String> textures) {
+        Set<String> layers = new LinkedHashSet<>();
+        for (JsonElement element : elements) {
+            JsonObject faces = element.getAsJsonObject().getAsJsonObject("faces");
+            if (faces == null) {
+                continue;
+            }
+            for (Map.Entry<String, JsonElement> face : faces.entrySet()) {
+                String texture = dereference(face.getValue().getAsJsonObject().get("texture").getAsString(), textures);
+                if (texture != null) {
+                    layers.add(texture);
+                }
+            }
+        }
+        return List.copyOf(layers);
+    }
+
+    private static int firstTintIndex(JsonArray elements) {
+        for (JsonElement element : elements) {
+            JsonObject faces = element.getAsJsonObject().getAsJsonObject("faces");
+            if (faces == null) {
+                continue;
+            }
+            for (Map.Entry<String, JsonElement> face : faces.entrySet()) {
+                int tintIndex = tintIndexOf(face.getValue().getAsJsonObject());
+                if (tintIndex != NO_TINT_INDEX) {
+                    return tintIndex;
+                }
+            }
+        }
+        return NO_TINT_INDEX;
+    }
+
+    static int tintIndexOf(JsonObject face) {
+        return face.has("tintindex") ? face.get("tintindex").getAsInt() : NO_TINT_INDEX;
+    }
+
+    private static JsonObject topmostFace(JsonArray elements, String faceName) {
+        JsonObject best = null;
+        double bestHeight = Double.NEGATIVE_INFINITY;
+        double bestArea = -1D;
+        for (JsonElement element : elements) {
+            JsonObject cuboid = element.getAsJsonObject();
+            JsonObject faces = cuboid.getAsJsonObject("faces");
+            if (faces == null || !faces.has(faceName)) {
+                continue;
+            }
+            JsonArray from = cuboid.getAsJsonArray("from");
+            JsonArray to = cuboid.getAsJsonArray("to");
+            double height = to.get(1).getAsDouble();
+            double area = (to.get(0).getAsDouble() - from.get(0).getAsDouble()) * (to.get(2).getAsDouble() - from.get(2).getAsDouble());
+            if (height > bestHeight || (height == bestHeight && area > bestArea)) {
+                best = faces.getAsJsonObject(faceName);
+                bestHeight = height;
+                bestArea = area;
+            }
+        }
+        return best;
+    }
+
+    static String dereference(String reference, Map<String, String> textures) {
+        String resolved = reference;
+        for (int hop = 0; resolved != null && resolved.startsWith("#") && hop < MAX_TEXTURE_REFERENCES; hop++) {
+            resolved = textures.get(resolved.substring(1));
+        }
+        return resolved == null || resolved.startsWith("#") ? null : resolved;
+    }
+
+    private static JsonObject pickVariant(JsonObject definition, Map<String, String> properties) {
+        if (definition.has("variants")) {
+            for (Map.Entry<String, JsonElement> variant : definition.getAsJsonObject("variants").entrySet()) {
+                if (variantMatches(variant.getKey(), properties)) {
+                    return firstModel(variant.getValue());
+                }
+            }
+            return null;
+        }
+        if (definition.has("multipart")) {
+            for (JsonElement part : definition.getAsJsonArray("multipart")) {
+                JsonObject rule = part.getAsJsonObject();
+                if (!rule.has("when") || conditionMatches(rule.getAsJsonObject("when"), properties)) {
+                    return firstModel(rule.get("apply"));
+                }
+            }
+        }
+        return null;
+    }
+
+    static boolean variantMatches(String variantKey, Map<String, String> properties) {
+        if (variantKey.isEmpty()) {
+            return true;
+        }
+        for (String condition : variantKey.split(",")) {
+            String[] pair = condition.split("=", 2);
+            if (pair.length != 2 || !pair[1].equals(properties.get(pair[0]))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    static boolean conditionMatches(JsonObject condition, Map<String, String> properties) {
+        if (condition.has("OR")) {
+            for (JsonElement option : condition.getAsJsonArray("OR")) {
+                if (conditionMatches(option.getAsJsonObject(), properties)) {
+                    return true;
+                }
+            }
+            return false;
+        }
+        if (condition.has("AND")) {
+            for (JsonElement requirement : condition.getAsJsonArray("AND")) {
+                if (!conditionMatches(requirement.getAsJsonObject(), properties)) {
+                    return false;
+                }
+            }
+            return true;
+        }
+        for (Map.Entry<String, JsonElement> requirement : condition.entrySet()) {
+            String actual = properties.get(requirement.getKey());
+            boolean anyAllowed = false;
+            for (String allowed : requirement.getValue().getAsString().split("\\|")) {
+                anyAllowed |= allowed.equals(actual);
+            }
+            if (!anyAllowed) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    static JsonObject firstModel(JsonElement models) {
+        if (models.isJsonArray()) {
+            JsonArray choices = models.getAsJsonArray();
+            return choices.isEmpty() ? null : choices.get(0).getAsJsonObject();
+        }
+        return models.getAsJsonObject();
+    }
+
+    static String assetPath(String resource, String folder, String extension) {
+        int separator = resource.indexOf(':');
+        String namespace = separator < 0 ? DEFAULT_NAMESPACE : resource.substring(0, separator);
+        String path = separator < 0 ? resource : resource.substring(separator + 1);
+        return "assets/" + namespace + "/" + folder + "/" + path + extension;
+    }
+
+    JsonObject readJson(String path) throws IOException {
+        return ClientJarFiles.readJson(clientJar, path);
+    }
+
+    // Each layer is drawn over the ones before it, using only its first frame when it is animated.
+    private BufferedImage readLayeredImage(List<String> layers) throws IOException {
+        BufferedImage bottom = readImage(assetPath(layers.get(0), "textures", ".png"));
+        if (bottom == null || layers.size() == 1) {
+            return bottom;
+        }
+        int size = bottom.getWidth();
+        BufferedImage combined = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
+        Graphics2D canvas = combined.createGraphics();
+        try {
+            for (String layer : layers) {
+                BufferedImage image = readImage(assetPath(layer, "textures", ".png"));
+                if (image != null) {
+                    int frameSize = image.getWidth();
+                    canvas.drawImage(image, 0, 0, size, size, 0, 0, frameSize, frameSize, null);
+                }
+            }
+        } finally {
+            canvas.dispose();
+        }
+        return combined;
+    }
+
+    private BufferedImage readImage(String path) throws IOException {
+        return ClientJarFiles.readImage(clientJar, path);
+    }
+
+    // Plants and other blocks without a top face only have a side-on sprite, which would read as stripes from above.
+    private record ModelFace(List<String> textures, int tintIndex, boolean isSideOnSprite) {
+    }
+
+    /**
+     * A block model with its parents' textures merged in. Models drawn in code, like chests, have no elements.
+     */
+    record ModelDefinition(Map<String, String> textures, JsonArray elements) {
+        ModelFace visibleFace(String faceName) {
+            ModelFace face = sideFace(faceName);
+            if (face != null) {
+                return face;
+            }
+            return elements != null && !spriteLayers(elements, textures).isEmpty() ? spriteFace() : particleFace();
+        }
+
+        // The face's texture on the model's topmost box, the particle texture for models without boxes, or null when
+        // the model leaves that side open.
+        ModelFace sideFace(String faceName) {
+            if (elements == null) {
+                return particleFace();
+            }
+            JsonObject face = topmostFace(elements, faceName);
+            if (face == null) {
+                return null;
+            }
+            String texture = dereference(face.get("texture").getAsString(), textures);
+            return texture == null ? null : new ModelFace(List.of(texture), tintIndexOf(face), false);
+        }
+
+        ModelFace spriteFace() {
+            return new ModelFace(spriteLayers(elements, textures), firstTintIndex(elements), true);
+        }
+
+        private ModelFace particleFace() {
+            String particle = dereference("#particle", textures);
+            return particle == null ? null : new ModelFace(List.of(particle), NO_TINT_INDEX, false);
+        }
+
+    }
+
+    private record ResolvedTexture(BlockTexture texture, boolean isSideOnSprite) {
+    }
+
+    record BlockStateId(String namespace, String name, Map<String, String> properties) {
+        static BlockStateId parse(String blockState) {
+            int propertiesStart = blockState.indexOf('[');
+            String id = propertiesStart < 0 ? blockState : blockState.substring(0, propertiesStart);
+            int separator = id.indexOf(':');
+            String namespace = separator < 0 ? DEFAULT_NAMESPACE : id.substring(0, separator);
+            String name = separator < 0 ? id : id.substring(separator + 1);
+            Map<String, String> properties = new HashMap<>();
+            if (propertiesStart >= 0) {
+                String body = blockState.substring(propertiesStart + 1, blockState.length() - 1);
+                for (String pair : body.split(",")) {
+                    String[] keyValue = pair.split("=", 2);
+                    if (keyValue.length == 2) {
+                        properties.put(keyValue[0], keyValue[1]);
+                    }
+                }
+            }
+            return new BlockStateId(namespace, name, properties);
+        }
+    }
+
+    // Biome tinted textures keep their grey pixels, because the biome colour changes from column to column.
+    // See-through pixels get a darker shade of the average colour, and the opaque mask remembers which they were.
+    // Textures with partly see-through pixels, like stained glass, ice and water, keep each pixel's alpha too.
+    record BlockTexture(int width, int height, int[] pixels, boolean[] opaque, int[] alphas, int averageColor,
+                        BiomeTint biomeTint) {
+        private static final double GAP_SHADE = 0.55D;
+        private static final int FULL_ALPHA = 255;
+
+        // Animated textures stack their frames vertically, so only the first square frame is used.
+        static BlockTexture fromImage(BufferedImage image, int fixedTint, BiomeTint biomeTint) {
+            return fromPixels(image, image.getWidth(), Math.min(image.getWidth(), image.getHeight()), fixedTint, biomeTint);
+        }
+
+        // Entity textures, like a chest's, are laid out for a model and can be wider than they are tall.
+        static BlockTexture fromWholeImage(BufferedImage image, int fixedTint) {
+            return fromPixels(image, image.getWidth(), image.getHeight(), fixedTint, null);
+        }
+
+        static BlockTexture solid(int color) {
+            return new BlockTexture(1, 1, new int[]{color}, new boolean[]{true}, null, color, null);
+        }
+
+        private static BlockTexture fromPixels(BufferedImage image, int width, int height, int fixedTint, BiomeTint biomeTint) {
+            int[] pixels = new int[width * height];
+            boolean[] opaque = new boolean[pixels.length];
+            int[] alphas = new int[pixels.length];
+            boolean translucent = false;
+            long red = 0;
+            long green = 0;
+            long blue = 0;
+            int opaqueCount = 0;
+            for (int y = 0; y < height; y++) {
+                for (int x = 0; x < width; x++) {
+                    int argb = image.getRGB(x, y);
+                    int index = y * width + x;
+                    int alpha = argb >>> 24;
+                    alphas[index] = alpha;
+                    if (alpha == 0) {
+                        continue;
+                    }
+                    translucent |= alpha < FULL_ALPHA;
+                    int color = multiply(argb & 0xFFFFFF, fixedTint);
+                    pixels[index] = color;
+                    opaque[index] = true;
+                    red += (color >>> 16) & 0xFF;
+                    green += (color >>> 8) & 0xFF;
+                    blue += color & 0xFF;
+                    opaqueCount++;
+                }
+            }
+            if (opaqueCount == 0) {
+                throw new IllegalArgumentException("Texture has no visible pixels");
+            }
+            int average = (int) (red / opaqueCount) << 16 | (int) (green / opaqueCount) << 8 | (int) (blue / opaqueCount);
+            int gapColor = BlockPreviewColors.shade(average, GAP_SHADE);
+            for (int index = 0; index < pixels.length; index++) {
+                if (!opaque[index]) {
+                    pixels[index] = gapColor;
+                }
+            }
+            return new BlockTexture(width, height, pixels, opaque, translucent ? alphas : null, average, biomeTint);
+        }
+
+        boolean isTranslucent() {
+            return alphas != null;
+        }
+
+        boolean isFullyOpaque() {
+            if (isTranslucent()) {
+                return false;
+            }
+            for (boolean pixelOpaque : opaque) {
+                if (!pixelOpaque) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        BlockTexture flattened() {
+            int[] flat = new int[pixels.length];
+            Arrays.fill(flat, averageColor);
+            boolean[] allOpaque = new boolean[pixels.length];
+            Arrays.fill(allOpaque, true);
+            return new BlockTexture(width, height, flat, allOpaque, null, averageColor, biomeTint);
+        }
+
+        BlockTexture tinted(int tint) {
+            int[] tintedPixels = new int[pixels.length];
+            for (int index = 0; index < pixels.length; index++) {
+                tintedPixels[index] = multiply(pixels[index], tint);
+            }
+            return new BlockTexture(width, height, tintedPixels, opaque, alphas, multiply(averageColor, tint), null);
+        }
+
+        int texelAt(double worldX, double worldZ) {
+            return pixels[texelIndex(worldX, worldZ)];
+        }
+
+        boolean isOpaqueAt(double worldX, double worldZ) {
+            return opaque[texelIndex(worldX, worldZ)];
+        }
+
+        private int texelIndex(double worldX, double worldZ) {
+            int x = Math.min(width - 1, (int) ((worldX - Math.floor(worldX)) * width));
+            int z = Math.min(height - 1, (int) ((worldZ - Math.floor(worldZ)) * height));
+            return z * width + x;
+        }
+
+        BufferedImage toImage() {
+            BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
+            image.setRGB(0, 0, width, height, pixels, 0, width);
+            return image;
+        }
+
+        // The GPU multiplies the texture by the tint in floating point and rounds back to 8 bits per channel.
+        static int multiply(int color, int tint) {
+            return multiplyChannel(color, tint, 16) << 16 | multiplyChannel(color, tint, 8) << 8 | multiplyChannel(color, tint, 0);
+        }
+
+        private static int multiplyChannel(int color, int tint, int shift) {
+            return (((color >>> shift) & 0xFF) * ((tint >>> shift) & 0xFF) + 127) / 255;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ClientJarFiles.java

@@ -0,0 +1,82 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+
+import javax.imageio.ImageIO;
+import java.awt.color.ColorSpace;
+import java.awt.image.BufferedImage;
+import java.awt.image.Raster;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+
+final class ClientJarFiles {
+    private ClientJarFiles() {
+    }
+
+    static JsonObject readJson(ZipFile clientJar, String path) throws IOException {
+        ZipEntry entry = clientJar.getEntry(path);
+        if (entry == null) {
+            return null;
+        }
+        try (InputStreamReader reader = new InputStreamReader(clientJar.getInputStream(entry), StandardCharsets.UTF_8)) {
+            return JsonParser.parseReader(reader).getAsJsonObject();
+        }
+    }
+
+    static BufferedImage readImage(ZipFile clientJar, String path) throws IOException {
+        ZipEntry entry = clientJar.getEntry(path);
+        if (entry == null) {
+            return null;
+        }
+        try (InputStream input = clientJar.getInputStream(entry)) {
+            BufferedImage image = ImageIO.read(input);
+            return image != null && isGrey(image) ? withGreyKept(image) : image;
+        }
+    }
+
+    private static boolean isGrey(BufferedImage image) {
+        return image.getColorModel().getColorSpace().getType() == ColorSpace.TYPE_GRAY;
+    }
+
+    // Java treats grey PNGs, like stone's, as linear light and brightens them when converting to RGB; Minecraft reads
+    // the stored values as they are.
+    private static BufferedImage withGreyKept(BufferedImage image) {
+        Raster raster = image.getRaster();
+        boolean hasAlpha = raster.getNumBands() > 1;
+        int greyMax = (1 << raster.getSampleModel().getSampleSize(0)) - 1;
+        int alphaMax = hasAlpha ? (1 << raster.getSampleModel().getSampleSize(1)) - 1 : 1;
+        BufferedImage converted = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);
+        for (int y = 0; y < image.getHeight(); y++) {
+            for (int x = 0; x < image.getWidth(); x++) {
+                int grey = raster.getSample(x, y, 0) * 255 / greyMax;
+                int alpha = hasAlpha ? raster.getSample(x, y, 1) * 255 / alphaMax : 255;
+                converted.setRGB(x, y, alpha << 24 | grey << 16 | grey << 8 | grey);
+            }
+        }
+        return converted;
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/CubeFace.java

@@ -0,0 +1,114 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+/**
+ * The six sides of a block, named as in Minecraft's model files, with the light Minecraft gives each side.
+ */
+enum CubeFace {
+    UP("up", 0, 1, 0, 1.0D),
+    DOWN("down", 0, -1, 0, 0.5D),
+    NORTH("north", 0, 0, -1, 0.8D),
+    SOUTH("south", 0, 0, 1, 0.8D),
+    EAST("east", 1, 0, 0, 0.6D),
+    WEST("west", -1, 0, 0, 0.6D);
+
+    private final String modelName;
+    private final int stepX;
+    private final int stepY;
+    private final int stepZ;
+    private final double shade;
+
+    CubeFace(String modelName, int stepX, int stepY, int stepZ, double shade) {
+        this.modelName = modelName;
+        this.stepX = stepX;
+        this.stepY = stepY;
+        this.stepZ = stepZ;
+        this.shade = shade;
+    }
+
+    static CubeFace named(String modelName) {
+        for (CubeFace face : values()) {
+            if (face.modelName.equals(modelName)) {
+                return face;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * The side a direction points at most, like Minecraft picks for a tilted face.
+     */
+    static CubeFace nearest(Vec3 direction) {
+        CubeFace nearest = UP;
+        double best = Double.NEGATIVE_INFINITY;
+        for (CubeFace face : values()) {
+            double alignment = face.stepX * direction.x() + face.stepY * direction.y() + face.stepZ * direction.z();
+            if (alignment > best) {
+                best = alignment;
+                nearest = face;
+            }
+        }
+        return nearest;
+    }
+
+    String modelName() {
+        return modelName;
+    }
+
+    int stepX() {
+        return stepX;
+    }
+
+    int stepY() {
+        return stepY;
+    }
+
+    int stepZ() {
+        return stepZ;
+    }
+
+    double shade() {
+        return shade;
+    }
+
+    Vec3 direction() {
+        return new Vec3(stepX, stepY, stepZ);
+    }
+
+    CubeFace opposite() {
+        return switch (this) {
+            case UP -> DOWN;
+            case DOWN -> UP;
+            case NORTH -> SOUTH;
+            case SOUTH -> NORTH;
+            case EAST -> WEST;
+            case WEST -> EAST;
+        };
+    }
+
+    int axis() {
+        return stepX != 0 ? 0 : stepY != 0 ? 1 : 2;
+    }
+
+    boolean pointsPositive() {
+        return stepX + stepY + stepZ > 0;
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/EmptyState.java

@@ -0,0 +1,102 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.Icon;
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.Font;
+import java.awt.FontMetrics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.awt.geom.RoundRectangle2D;
+
+/**
+ * What an empty view says, drawn in the middle of it the way IntelliJ fills an empty tool window: a large icon, what
+ * is missing, and where to add it.
+ *
+ * @param location the pack folder or file the hint points to, drawn as code
+ */
+record EmptyState(Icon icon, String title, String hint, String location, String footer) {
+    private static final int ICON_GAP = 18;
+    private static final int TITLE_GAP = 8;
+    private static final int LOCATION_GAP = 10;
+    private static final int FOOTER_GAP = 14;
+    private static final int CHIP_PADDING_X = 8;
+    private static final int CHIP_PADDING_Y = 4;
+    private static final int CHIP_ARC = 8;
+
+    /**
+     * Draws the empty state centred on the given point.
+     */
+    void paint(Graphics2D graphics, Component owner, int centerX, int centerY) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+            canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+            int top = centerY - height(canvas) / 2;
+            icon.paintIcon(owner, canvas, centerX - icon.getIconWidth() / 2, top);
+            top += icon.getIconHeight() + StudioTheme.scale(ICON_GAP);
+            top = drawCentered(canvas, title, StudioTheme.titleFont(), StudioTheme.TEXT, centerX, top);
+            top = drawCentered(canvas, hint, StudioTheme.font(), StudioTheme.SECONDARY_TEXT, centerX,
+                    top + StudioTheme.scale(TITLE_GAP));
+            top = drawLocationChip(canvas, centerX, top + StudioTheme.scale(LOCATION_GAP));
+            drawCentered(canvas, footer, StudioTheme.smallFont(), StudioTheme.MUTED_TEXT, centerX, top + StudioTheme.scale(FOOTER_GAP));
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private int height(Graphics2D canvas) {
+        return icon.getIconHeight() + StudioTheme.scale(ICON_GAP)
+                + canvas.getFontMetrics(StudioTheme.titleFont()).getHeight()
+                + StudioTheme.scale(TITLE_GAP) + canvas.getFontMetrics(StudioTheme.font()).getHeight()
+                + StudioTheme.scale(LOCATION_GAP) + chipHeight(canvas)
+                + StudioTheme.scale(FOOTER_GAP) + canvas.getFontMetrics(StudioTheme.smallFont()).getHeight();
+    }
+
+    private int chipHeight(Graphics2D canvas) {
+        return canvas.getFontMetrics(StudioTheme.monospacedFont()).getHeight() + StudioTheme.scale(CHIP_PADDING_Y) * 2;
+    }
+
+    private int drawLocationChip(Graphics2D canvas, int centerX, int top) {
+        canvas.setFont(StudioTheme.monospacedFont());
+        FontMetrics metrics = canvas.getFontMetrics();
+        int width = metrics.stringWidth(location) + StudioTheme.scale(CHIP_PADDING_X) * 2;
+        int height = chipHeight(canvas);
+        int left = centerX - width / 2;
+        RoundRectangle2D chip = new RoundRectangle2D.Double(left + 0.5D, top + 0.5D, width - 1D, height - 1D,
+                StudioTheme.scale(CHIP_ARC), StudioTheme.scale(CHIP_ARC));
+        canvas.setColor(StudioTheme.PANEL_BACKGROUND);
+        canvas.fill(chip);
+        canvas.setColor(StudioTheme.CONTROL_BORDER);
+        canvas.draw(chip);
+        canvas.setColor(StudioTheme.TEXT);
+        canvas.drawString(location, left + StudioTheme.scale(CHIP_PADDING_X), top + StudioTheme.scale(CHIP_PADDING_Y) + metrics.getAscent());
+        return top + height;
+    }
+
+    private static int drawCentered(Graphics2D canvas, String text, Font font, Color color, int centerX, int top) {
+        canvas.setFont(font);
+        canvas.setColor(color);
+        FontMetrics metrics = canvas.getFontMetrics();
+        canvas.drawString(text, centerX - metrics.stringWidth(text) / 2, top + metrics.getAscent());
+        return top + metrics.getHeight();
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/EntityBlockShapes.java

@@ -0,0 +1,298 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.BlockModel.Face;
+import com.volmit.iris.core.gui.BlockModel.TextureMapping;
+import com.volmit.iris.core.gui.BlockTextures.BlockStateId;
+import com.volmit.iris.core.gui.BlockTextures.BlockTexture;
+import com.volmit.iris.core.gui.BlockTextures.ModelDefinition;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+
+/**
+ * Shapes for the blocks Minecraft draws in code instead of from a model file, like chests, heads, banners and
+ * fluids, which fill their block. Chests, heads, banners and the bell use their entity textures laid out the way Minecraft's model parts are;
+ * rarer ones are a simple box in their particle texture.
+ */
+final class EntityBlockShapes {
+    private static final Set<String> INVISIBLE = Set.of("air", "cave_air", "void_air", "barrier", "light",
+            "structure_void", "moving_piston", "pitcher_crop");
+    private static final int END_PORTAL_COLOR = 0x0E1219;
+    private static final double SKULL_WALL_OFFSET = 0.25D;
+    private static final double ROTATION_SEGMENT_DEGREES = 22.5D;
+    private static final double BANNER_SCALE = 2D / 3D;
+    private static final double MODEL_UNITS = 16D;
+    private static final Map<String, Integer> DYE_COLORS = Map.ofEntries(
+            Map.entry("white", 0xF9FFFE), Map.entry("orange", 0xF9801D), Map.entry("magenta", 0xC74EBD),
+            Map.entry("light_blue", 0x3AB3DA), Map.entry("yellow", 0xFED83D), Map.entry("lime", 0x80C71F),
+            Map.entry("pink", 0xF38BAA), Map.entry("gray", 0x474F52), Map.entry("light_gray", 0x9D9D97),
+            Map.entry("cyan", 0x169C9C), Map.entry("purple", 0x8932B8), Map.entry("blue", 0x3C44AA),
+            Map.entry("brown", 0x835432), Map.entry("green", 0x5E7C16), Map.entry("red", 0xB02E26),
+            Map.entry("black", 0x1D1D21));
+
+    private final BlockTextures textures;
+
+    EntityBlockShapes(BlockTextures textures) {
+        this.textures = textures;
+    }
+
+    /**
+     * The faces of a block whose model has no boxes of its own.
+     */
+    List<Face> facesOf(BlockStateId state, ModelDefinition model) {
+        String name = state.name();
+        if (INVISIBLE.contains(name)) {
+            return List.of();
+        }
+        if (name.endsWith("chest")) {
+            return chest(state);
+        }
+        if (name.endsWith("_skull") || name.endsWith("_head")) {
+            return head(state, model);
+        }
+        if (name.endsWith("banner")) {
+            return banner(state);
+        }
+        return switch (name) {
+            case "conduit" -> particleBox(state, model, new Vec3(5, 5, 5), new Vec3(11, 11, 11), false);
+            case "decorated_pot" -> decoratedPot(state, model);
+            case "end_portal" -> BlockModelBuilder.box(new Vec3(0, 0, 0), new Vec3(16, 12, 16), BlockTexture.solid(END_PORTAL_COLOR), true);
+            case "end_gateway" -> BlockModelBuilder.box(new Vec3(0, 0, 0), new Vec3(16, 16, 16), BlockTexture.solid(END_PORTAL_COLOR), true);
+            default -> name.endsWith("copper_golem_statue")
+                    ? particleBox(state, model, new Vec3(4, 0, 4), new Vec3(12, 14, 12), false)
+                    : particleBox(state, model, new Vec3(0, 0, 0), new Vec3(16, 16, 16), true);
+        };
+    }
+
+    /**
+     * Parts a block draws in code on top of its model, like the bell hanging in its frame.
+     */
+    List<Face> facesAddedTo(BlockStateId state) {
+        if (!state.name().equals("bell")) {
+            return List.of();
+        }
+        Optional<BlockTexture> texture = textures.entityTexture("entity/bell/bell_body", MinecraftBlockTints.NO_TINT);
+        if (texture.isEmpty()) {
+            return List.of();
+        }
+        List<Face> faces = new ArrayList<>();
+        faces.addAll(modelPartBox(texture.get(), 0, 0, new Vec3(5, 6, 5), new Vec3(6, 7, 6), Transform.IDENTITY));
+        faces.addAll(modelPartBox(texture.get(), 0, 13, new Vec3(4, 4, 4), new Vec3(8, 2, 8), Transform.IDENTITY));
+        return faces;
+    }
+
+    private List<Face> particleBox(BlockStateId state, ModelDefinition model, Vec3 from, Vec3 to, boolean culledBySides) {
+        String particle = BlockTextures.dereference("#particle", model.textures());
+        if (particle == null) {
+            return List.of();
+        }
+        return textures.faceTexture(state, particle, BlockTextures.NO_TINT_INDEX)
+                .map(texture -> BlockModelBuilder.box(from, to, texture, culledBySides))
+                .orElse(List.of());
+    }
+
+    private List<Face> decoratedPot(BlockStateId state, ModelDefinition model) {
+        List<Face> faces = new ArrayList<>(particleBox(state, model, new Vec3(1, 0, 1), new Vec3(15, 16, 15), false));
+        faces.addAll(particleBox(state, model, new Vec3(4, 16, 4), new Vec3(12, 20, 12), false));
+        return faces;
+    }
+
+    // Single chests are 14 pixels wide; each half of a double chest is 15, reaching over to its partner.
+    private List<Face> chest(BlockStateId state) {
+        String type = state.properties().getOrDefault("type", "single");
+        String suffix = type.equals("single") ? "" : "_" + type;
+        Optional<BlockTexture> texture = textures.entityTexture("entity/chest/" + chestTextureName(state.name()) + suffix, MinecraftBlockTints.NO_TINT);
+        if (texture.isEmpty()) {
+            return List.of();
+        }
+        Transform place = Transform.IDENTITY
+                .translate(0.5D, 0.5D, 0.5D)
+                .rotateY(-yRotationOf(state.properties().getOrDefault("facing", "north")))
+                .translate(-0.5D, -0.5D, -0.5D);
+        double left = type.equals("left") ? 0D : 1D;
+        double width = type.equals("single") ? 14D : 15D;
+        double lockX = switch (type) {
+            case "left" -> 0D;
+            case "right" -> 15D;
+            default -> 7D;
+        };
+        double lockWidth = type.equals("single") ? 2D : 1D;
+        List<Face> faces = new ArrayList<>();
+        faces.addAll(modelPartBox(texture.get(), 0, 19, new Vec3(left, 0, 1), new Vec3(width, 10, 14), place));
+        faces.addAll(modelPartBox(texture.get(), 0, 0, new Vec3(left, 9, 1), new Vec3(width, 5, 14), place));
+        faces.addAll(modelPartBox(texture.get(), 0, 0, new Vec3(lockX, 7, 15), new Vec3(lockWidth, 4, 1), place));
+        return faces;
+    }
+
+    private static String chestTextureName(String blockName) {
+        String name = blockName.startsWith("waxed_") ? blockName.substring("waxed_".length()) : blockName;
+        return switch (name) {
+            case "trapped_chest" -> "trapped";
+            case "ender_chest" -> "ender";
+            case "copper_chest" -> "copper";
+            case "exposed_copper_chest" -> "copper_exposed";
+            case "weathered_copper_chest" -> "copper_weathered";
+            case "oxidized_copper_chest" -> "copper_oxidized";
+            default -> "normal";
+        };
+    }
+
+    // Heads are drawn upside down and mirrored in their model, and turn in sixteenths like signs.
+    private List<Face> head(BlockStateId state, ModelDefinition model) {
+        boolean onWall = state.name().contains("_wall_");
+        String kind = state.name().replace("_wall_", "_");
+        Optional<HeadLook> look = HeadLook.of(kind);
+        Optional<BlockTexture> texture = look.flatMap(found -> textures.entityTexture(found.texture(), MinecraftBlockTints.NO_TINT));
+        if (texture.isEmpty()) {
+            return onWall
+                    ? particleBox(state, model, new Vec3(4, 4, 8), new Vec3(12, 12, 16), false)
+                    : particleBox(state, model, new Vec3(4, 0, 4), new Vec3(12, 8, 12), false);
+        }
+        Transform place;
+        if (onWall) {
+            CubeFace facing = CubeFace.named(state.properties().getOrDefault("facing", "north"));
+            place = Transform.IDENTITY
+                    .translate(0.5D - facing.stepX() * SKULL_WALL_OFFSET, SKULL_WALL_OFFSET, 0.5D - facing.stepZ() * SKULL_WALL_OFFSET)
+                    .scale(-1D, -1D, 1D)
+                    .rotateY(yRotationOf(facing.opposite().modelName()));
+        } else {
+            int rotation = Integer.parseInt(state.properties().getOrDefault("rotation", "0"));
+            place = Transform.IDENTITY
+                    .translate(0.5D, 0D, 0.5D)
+                    .scale(-1D, -1D, 1D)
+                    .rotateY(rotation * ROTATION_SEGMENT_DEGREES);
+        }
+        HeadLook found = look.get();
+        return modelPartBox(texture.get(), 0, 0, new Vec3(-found.width() / 2D, -8, -4), new Vec3(found.width(), 8, 8), place);
+    }
+
+    private List<Face> banner(BlockStateId state) {
+        boolean onWall = state.name().endsWith("_wall_banner");
+        String color = state.name().substring(0, state.name().length() - (onWall ? "_wall_banner" : "_banner").length());
+        Optional<BlockTexture> frame = textures.entityTexture("entity/banner/banner_base", MinecraftBlockTints.NO_TINT);
+        Optional<BlockTexture> cloth = textures.entityTexture("entity/banner/base", DYE_COLORS.getOrDefault(color, MinecraftBlockTints.NO_TINT));
+        if (frame.isEmpty() || cloth.isEmpty()) {
+            return List.of();
+        }
+        Transform place;
+        if (onWall) {
+            CubeFace facing = CubeFace.named(state.properties().getOrDefault("facing", "north"));
+            place = Transform.IDENTITY
+                    .translate(0.5D, -1D / 6D, 0.5D)
+                    .rotateY(-yRotationOf(facing.modelName()))
+                    .translate(0D, -0.3125D, -0.4375D)
+                    .scale(BANNER_SCALE, -BANNER_SCALE, -BANNER_SCALE);
+        } else {
+            int rotation = Integer.parseInt(state.properties().getOrDefault("rotation", "0"));
+            place = Transform.IDENTITY
+                    .translate(0.5D, 0.5D, 0.5D)
+                    .rotateY(-rotation * ROTATION_SEGMENT_DEGREES)
+                    .scale(BANNER_SCALE, -BANNER_SCALE, -BANNER_SCALE);
+        }
+        List<Face> faces = new ArrayList<>();
+        if (!onWall) {
+            faces.addAll(modelPartBox(frame.get(), 44, 0, new Vec3(-1, -30, -1), new Vec3(2, 42, 2), place));
+        }
+        faces.addAll(modelPartBox(frame.get(), 0, 42, new Vec3(-10, -32, -1), new Vec3(20, 2, 2), place));
+        faces.addAll(modelPartBox(cloth.get(), 0, 0, new Vec3(-10, -32, -2), new Vec3(20, 40, 1), place));
+        return faces;
+    }
+
+    // Minecraft's facing angle: south is 0 and each quarter turn clockwise seen from above adds 90 degrees.
+    private static double yRotationOf(String facing) {
+        return switch (facing) {
+            case "west" -> 90D;
+            case "north" -> 180D;
+            case "east" -> 270D;
+            default -> 0D;
+        };
+    }
+
+    /**
+     * A box of a block entity's model, in model pixels, with its sides laid out on the texture the way Minecraft's
+     * model parts are: the top and bottom in a row above the four sides.
+     */
+    static List<Face> modelPartBox(BlockTexture texture, int textureU, int textureV, Vec3 from, Vec3 size, Transform place) {
+        double minX = from.x() / MODEL_UNITS;
+        double minY = from.y() / MODEL_UNITS;
+        double minZ = from.z() / MODEL_UNITS;
+        double maxX = (from.x() + size.x()) / MODEL_UNITS;
+        double maxY = (from.y() + size.y()) / MODEL_UNITS;
+        double maxZ = (from.z() + size.z()) / MODEL_UNITS;
+        Vec3 v0 = new Vec3(minX, minY, minZ);
+        Vec3 v1 = new Vec3(maxX, minY, minZ);
+        Vec3 v2 = new Vec3(maxX, maxY, minZ);
+        Vec3 v3 = new Vec3(minX, maxY, minZ);
+        Vec3 v4 = new Vec3(minX, minY, maxZ);
+        Vec3 v5 = new Vec3(maxX, minY, maxZ);
+        Vec3 v6 = new Vec3(maxX, maxY, maxZ);
+        Vec3 v7 = new Vec3(minX, maxY, maxZ);
+        double u = textureU;
+        double v = textureV;
+        double width = size.x();
+        double height = size.y();
+        double depth = size.z();
+        List<Face> faces = new ArrayList<>(6);
+        faces.add(polygon(texture, place, CubeFace.DOWN, v5, v4, v0, u + depth, v, u + depth + width, v + depth));
+        faces.add(polygon(texture, place, CubeFace.UP, v2, v3, v7, u + depth + width, v + depth, u + depth + width + width, v));
+        faces.add(polygon(texture, place, CubeFace.WEST, v0, v4, v7, u, v + depth, u + depth, v + depth + height));
+        faces.add(polygon(texture, place, CubeFace.NORTH, v1, v0, v3, u + depth, v + depth, u + depth + width, v + depth + height));
+        faces.add(polygon(texture, place, CubeFace.EAST, v5, v1, v2, u + depth + width, v + depth, u + depth + width + depth, v + depth + height));
+        faces.add(polygon(texture, place, CubeFace.SOUTH, v4, v5, v6, u + depth + width + depth, v + depth, u + depth + width + depth + width, v + depth + height));
+        return faces;
+    }
+
+    // A model part's polygon gives its first corner (u2, v1), its second (u1, v1) and its third (u1, v2).
+    private static Face polygon(BlockTexture texture, Transform place, CubeFace side, Vec3 first, Vec3 second, Vec3 third,
+                                double u1, double v1, double u2, double v2) {
+        double textureWidth = texture.width();
+        double textureHeight = texture.height();
+        TextureMapping mapping = new TextureMapping(u1 / textureWidth, v1 / textureHeight,
+                (u2 - u1) / textureWidth, 0D, 0D, (v2 - v1) / textureHeight);
+        Face face = new Face(second, first.minus(second), third.minus(second), side.direction(), texture, mapping, side.shade(), null)
+                .transformed(place);
+        return face.withShade(CubeFace.nearest(face.normal()).shade());
+    }
+
+    /**
+     * The entity texture of a mob head and how wide its head is.
+     */
+    private record HeadLook(String texture, double width) {
+        private static final double HEAD_WIDTH = 8D;
+        private static final double PIGLIN_HEAD_WIDTH = 10D;
+
+        static Optional<HeadLook> of(String kind) {
+            return Optional.ofNullable(switch (kind) {
+                case "skeleton_skull" -> new HeadLook("entity/skeleton/skeleton", HEAD_WIDTH);
+                case "wither_skeleton_skull" -> new HeadLook("entity/skeleton/wither_skeleton", HEAD_WIDTH);
+                case "zombie_head" -> new HeadLook("entity/zombie/zombie", HEAD_WIDTH);
+                case "creeper_head" -> new HeadLook("entity/creeper/creeper", HEAD_WIDTH);
+                case "player_head" -> new HeadLook("entity/player/wide/steve", HEAD_WIDTH);
+                case "piglin_head" -> new HeadLook("entity/piglin/piglin", PIGLIN_HEAD_WIDTH);
+                default -> null;
+            });
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/GuiHost.java

@@ -0,0 +1,224 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.events.IrisEngineHotloadEvent;
+import com.volmit.iris.core.project.IrisProject;
+import com.volmit.iris.core.service.PreservationSVC;
+import com.volmit.iris.core.service.StudioSVC;
+import com.volmit.iris.core.tools.IrisToolbelt;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.platform.PlatformChunkGenerator;
+import org.bukkit.Bukkit;
+import org.bukkit.World;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+
+import javax.swing.JFrame;
+import java.awt.Desktop;
+import java.awt.Dimension;
+import java.awt.EventQueue;
+import java.awt.GraphicsEnvironment;
+import java.awt.Rectangle;
+import java.awt.desktop.QuitResponse;
+import java.awt.image.BufferedImage;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
+import java.util.ArrayList;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public final class GuiHost {
+    private static final AtomicBoolean DESKTOP_QUIT_GUARD_INSTALLED = new AtomicBoolean(false);
+    private static final Set<JFrame> MANAGED_FRAMES = ConcurrentHashMap.newKeySet();
+    private static final Map<Runnable, Listener> HOTLOAD_HOOKS = new ConcurrentHashMap<>();
+
+    private GuiHost() {
+    }
+
+    public static boolean isAvailable() {
+        return !GraphicsEnvironment.isHeadless();
+    }
+
+    public static JFrame createFrame(String title) {
+        XwaylandWindowManagerHint.apply();
+        StudioTheme.install();
+        JFrame frame = new JFrame(title);
+        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
+        MANAGED_FRAMES.add(frame);
+        frame.addWindowListener(new WindowAdapter() {
+            @Override
+            public void windowClosed(WindowEvent event) {
+                MANAGED_FRAMES.remove(frame);
+            }
+
+            @Override
+            public void windowActivated(WindowEvent event) {
+                StudioTheme.followSystem();
+            }
+        });
+        installMacQuitGuard();
+        return frame;
+    }
+
+    /**
+     * Wraps rendered pixels in an image Java2D draws straight from memory. Left to itself Java2D copies every image it
+     * draws into a texture inside the display server; with a map's hundreds of tiles that crashed Xwayland's Intel driver
+     * and took every X window on the desktop down with it.
+     */
+    public static BufferedImage uncachedImage(int[] pixels, int width, int height) {
+        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
+        image.getRaster().setDataElements(0, 0, width, height, pixels);
+        image.setAccelerationPriority(0F);
+        return image;
+    }
+
+    // A scaled-up default size can be bigger than a small or low resolution screen.
+    static Dimension fitToScreen(Dimension preferred) {
+        Rectangle usable = GraphicsEnvironment.getLocalGraphicsEnvironment().getMaximumWindowBounds();
+        return new Dimension(Math.min(preferred.width, usable.width), Math.min(preferred.height, usable.height));
+    }
+
+    /**
+     * The engine of the open studio project, which reads the pack folder you edit, or else the first Iris world.
+     * A normal Iris world runs on its own copy of the pack, made when the world was created.
+     */
+    public static Engine findActiveEngine() {
+        Engine studioEngine = findStudioEngine();
+        if (studioEngine != null) {
+            return studioEngine;
+        }
+        try {
+            for (World world : new ArrayList<>(Bukkit.getWorlds())) {
+                Engine engine = engineOf(world);
+                if (engine != null) {
+                    return engine;
+                }
+            }
+        } catch (Throwable ignored) {
+        }
+        return null;
+    }
+
+    private static Engine findStudioEngine() {
+        try {
+            StudioSVC studio = Iris.service(StudioSVC.class);
+            IrisProject project = studio == null || !studio.isProjectOpen() ? null : studio.getActiveProject();
+            PlatformChunkGenerator provider = project == null ? null : project.getActiveProvider();
+            Engine engine = provider == null ? null : provider.getEngine();
+            return engine == null || engine.isClosed() ? null : engine;
+        } catch (Throwable ignored) {
+            return null;
+        }
+    }
+
+    public static Engine findEngine(UUID worldId) {
+        World world = Bukkit.getWorld(worldId);
+        return world == null ? null : engineOf(world);
+    }
+
+    public static void registerHotloadHook(Runnable onHotload) {
+        Listener listener = new HotloadListener(onHotload);
+        HOTLOAD_HOOKS.put(onHotload, listener);
+        Iris.instance.registerListener(listener);
+    }
+
+    public static void unregisterHotloadHook(Runnable onHotload) {
+        Listener listener = HOTLOAD_HOOKS.remove(onHotload);
+        if (listener != null) {
+            Iris.instance.unregisterListener(listener);
+        }
+    }
+
+    static void interruptOnPluginShutdown(ExecutorService executor) {
+        PreservationSVC preservation = Iris.service(PreservationSVC.class);
+        if (preservation != null) {
+            preservation.register(executor);
+        }
+    }
+
+    static void interruptOnPluginShutdown(Thread thread) {
+        PreservationSVC preservation = Iris.service(PreservationSVC.class);
+        if (preservation != null) {
+            preservation.register(thread);
+        }
+    }
+
+    private static Engine engineOf(World world) {
+        try {
+            PlatformChunkGenerator access = IrisToolbelt.access(world);
+            if (access != null && access.getEngine() != null && !access.getEngine().isClosed()) {
+                return access.getEngine();
+            }
+        } catch (Throwable ignored) {
+        }
+        return null;
+    }
+
+    // macOS Quit in the dock menu would otherwise stop the whole server.
+    private static void installMacQuitGuard() {
+        if (!isAvailable()
+                || !System.getProperty("os.name", "").toLowerCase(Locale.ROOT).contains("mac")
+                || !DESKTOP_QUIT_GUARD_INSTALLED.compareAndSet(false, true)) {
+            return;
+        }
+
+        try {
+            if (!Desktop.isDesktopSupported()) {
+                return;
+            }
+            Desktop desktop = Desktop.getDesktop();
+            if (!desktop.isSupported(Desktop.Action.APP_QUIT_HANDLER)) {
+                return;
+            }
+            desktop.setQuitHandler((event, response) -> closeWindowsAndCancelQuit(response));
+        } catch (Throwable e) {
+            Iris.reportError(e);
+            Iris.info("Unable to install the Iris desktop quit guard; use the server stop command instead of macOS Quit");
+        }
+    }
+
+    private static void closeWindowsAndCancelQuit(QuitResponse response) {
+        response.cancelQuit();
+        EventQueue.invokeLater(() -> {
+            for (JFrame frame : MANAGED_FRAMES) {
+                frame.dispose();
+            }
+        });
+    }
+
+    private static final class HotloadListener implements Listener {
+        private final Runnable onHotload;
+
+        private HotloadListener(Runnable onHotload) {
+            this.onHotload = onHotload;
+        }
+
+        @EventHandler
+        public void on(IrisEngineHotloadEvent event) {
+            onHotload.run();
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/GuiMarker.java

@@ -0,0 +1,29 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+public record GuiMarker(String label, double worldX, double worldY, double worldZ, double health, double maxHealth) {
+    public static GuiMarker player(String name, double worldX, double worldZ) {
+        return new GuiMarker(name, worldX, 0, worldZ, 0, 0);
+    }
+
+    public static GuiMarker entity(String label, double worldX, double worldY, double worldZ, double health, double maxHealth) {
+        return new GuiMarker(label, worldX, worldY, worldZ, health, maxHealth);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/IslandOverlay.java

@@ -0,0 +1,105 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.JComponent;
+import javax.swing.JLayeredPane;
+import java.awt.Cursor;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+
+/**
+ * Lays an island over content that fills the whole area behind it. Dragging the island's right edge resizes it,
+ * always leaving the content some room beside it.
+ */
+final class IslandOverlay extends JLayeredPane {
+    private static final long serialVersionUID = -4182209135360718342L;
+
+    private final IslandPanel island;
+    private final JComponent background;
+    private final int minimumIslandWidth;
+    private final int minimumUncoveredWidth;
+    private int islandWidth;
+
+    IslandOverlay(IslandPanel island, JComponent background, int islandWidth, int minimumIslandWidth, int minimumUncoveredWidth) {
+        this.island = island;
+        this.background = background;
+        this.islandWidth = islandWidth;
+        this.minimumIslandWidth = minimumIslandWidth;
+        this.minimumUncoveredWidth = minimumUncoveredWidth;
+        add(background, JLayeredPane.DEFAULT_LAYER);
+        add(island, JLayeredPane.PALETTE_LAYER);
+        installResizing();
+    }
+
+    @Override
+    public void doLayout() {
+        background.setBounds(0, 0, getWidth(), getHeight());
+        island.setBounds(0, 0, clampedIslandWidth(), getHeight());
+    }
+
+    private int clampedIslandWidth() {
+        int widest = Math.max(minimumIslandWidth, getWidth() - minimumUncoveredWidth);
+        return Math.clamp(islandWidth, minimumIslandWidth, widest);
+    }
+
+    private void installResizing() {
+        MouseAdapter resizer = new MouseAdapter() {
+            private boolean dragging;
+
+            @Override
+            public void mouseMoved(MouseEvent event) {
+                island.setCursor(island.isOnResizeEdge(event.getX(), event.getY())
+                        ? Cursor.getPredefinedCursor(Cursor.E_RESIZE_CURSOR)
+                        : Cursor.getDefaultCursor());
+            }
+
+            @Override
+            public void mouseExited(MouseEvent event) {
+                if (!dragging) {
+                    island.setCursor(Cursor.getDefaultCursor());
+                }
+            }
+
+            @Override
+            public void mousePressed(MouseEvent event) {
+                dragging = island.isOnResizeEdge(event.getX(), event.getY());
+            }
+
+            @Override
+            public void mouseDragged(MouseEvent event) {
+                if (!dragging) {
+                    return;
+                }
+                islandWidth = event.getX();
+                islandWidth = clampedIslandWidth();
+                revalidate();
+                repaint();
+            }
+
+            @Override
+            public void mouseReleased(MouseEvent event) {
+                dragging = false;
+            }
+        };
+        island.addMouseListener(resizer);
+        island.addMouseMotionListener(resizer);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/IslandPanel.java

@@ -0,0 +1,77 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.JComponent;
+import javax.swing.JPanel;
+import java.awt.BorderLayout;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.awt.geom.RoundRectangle2D;
+
+/**
+ * A rounded panel floating over the window content with a gap all around it, like the tool windows of IntelliJ's
+ * islands theme. The gap belongs to the content behind it, except for the strip along the right edge, which grabs the
+ * island to resize it.
+ */
+final class IslandPanel extends JPanel {
+    private static final long serialVersionUID = 7313084027614358519L;
+    private static final int GAP = 6;
+    private static final int CORNER_ARC = 12;
+    private static final int INNER_PADDING = 4;
+
+    IslandPanel(JComponent content) {
+        super(new BorderLayout());
+        setOpaque(false);
+        int inset = GAP + INNER_PADDING;
+        setBorder(StudioTheme.emptyBorder(inset, inset, inset, inset));
+        add(content, BorderLayout.CENTER);
+    }
+
+    boolean isOnResizeEdge(int x, int y) {
+        int edgeWidth = StudioTheme.scale(GAP + INNER_PADDING);
+        return x >= getWidth() - edgeWidth && x < getWidth() && y >= 0 && y < getHeight();
+    }
+
+    // Clicks in the gap reach the content behind the island instead of the island itself.
+    @Override
+    public boolean contains(int x, int y) {
+        return island().contains(x, y) || isOnResizeEdge(x, y);
+    }
+
+    @Override
+    protected void paintComponent(Graphics graphics) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+            canvas.setColor(StudioTheme.PANEL_BACKGROUND);
+            canvas.fill(island());
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private RoundRectangle2D island() {
+        double gap = StudioTheme.scale(GAP);
+        double arc = StudioTheme.scale(CORNER_ARC);
+        return new RoundRectangle2D.Double(gap, gap, getWidth() - gap * 2D, getHeight() - gap * 2D, arc, arc);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/LatestMeasurement.java

@@ -0,0 +1,81 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.Iris;
+
+import java.awt.EventQueue;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+/**
+ * Measures off the Swing thread, one measurement at a time, and only hands back the newest one asked for.
+ */
+final class LatestMeasurement<T> {
+    private final ThreadPoolExecutor worker;
+    private final AtomicLong generation = new AtomicLong();
+
+    LatestMeasurement(String threadName) {
+        this.worker = new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, new ArrayBlockingQueue<>(1), task -> {
+            Thread thread = new Thread(task, threadName);
+            thread.setDaemon(true);
+            return thread;
+        }, new ThreadPoolExecutor.DiscardOldestPolicy());
+    }
+
+    /**
+     * Runs the measurement and shows its result on the Swing thread, unless another was asked for meanwhile or it
+     * measured nothing.
+     */
+    void measure(Supplier<T> measurement, Consumer<T> show) {
+        long requested = generation.incrementAndGet();
+        worker.execute(() -> {
+            T result = measureSafely(measurement);
+            EventQueue.invokeLater(() -> {
+                if (requested == generation.get() && result != null) {
+                    show.accept(result);
+                }
+            });
+        });
+    }
+
+    /**
+     * Drops the measurement under way, whose result no longer fits.
+     */
+    void discardPending() {
+        generation.incrementAndGet();
+    }
+
+    void close() {
+        worker.shutdownNow();
+    }
+
+    private static <T> T measureSafely(Supplier<T> measurement) {
+        try {
+            return measurement.get();
+        } catch (Throwable error) {
+            Iris.reportError(error);
+            return null;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/LoadingAnimation.java

@@ -0,0 +1,145 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.volmit.iris.core.gui;
+
+import java.awt.AlphaComposite;
+import java.awt.Color;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.awt.geom.Path2D;
+import java.awt.image.BufferedImage;
+
+/**
+ * A little cube of blocks building itself while something loads: the blocks drop in one by one, the cube holds a
+ * moment, fades, and starts over. Loads shorter than {@link #SHOW_AFTER_MILLIS} never show it, so they don't flash.
+ */
+final class LoadingAnimation {
+    static final int SHOW_AFTER_MILLIS = 300;
+    static final int FRAME_MILLIS = 33;
+
+    // Back to front, so each block lands on or beside ones already there.
+    private static final int[][] BUILD_ORDER = {
+            {0, 0, 0}, {1, 0, 0}, {0, 0, 1}, {1, 0, 1},
+            {0, 1, 0}, {1, 1, 0}, {0, 1, 1}, {1, 1, 1}};
+    private static final int STEP_MILLIS = 140;
+    private static final int DROP_MILLIS = 260;
+    private static final int HOLD_MILLIS = 450;
+    private static final int FADE_MILLIS = 320;
+    private static final int CYCLE_MILLIS = STEP_MILLIS * (BUILD_ORDER.length - 1) + DROP_MILLIS + HOLD_MILLIS + FADE_MILLIS;
+    private static final double DROP_HEIGHT_BLOCKS = 1.6D;
+    private static final double ISOMETRIC_WIDTH = Math.cos(Math.PI / 6D);
+    private static final double ISOMETRIC_DEPTH = 0.5D;
+    private static final float SIDE_SHADE = 0.78F;
+    private static final float FAR_SIDE_SHADE = 0.6F;
+
+    private LoadingAnimation() {
+    }
+
+    /**
+     * Whether a load that began at {@code loadingSinceMillis} has taken long enough to show the animation.
+     */
+    static boolean isDue(long loadingSinceMillis) {
+        return System.currentTimeMillis() - loadingSinceMillis >= SHOW_AFTER_MILLIS;
+    }
+
+    /**
+     * Draws the cube centred on a point, {@code blockSize} pixels to a block edge, as it looks
+     * {@code elapsedMillis} after it first showed.
+     */
+    static void paint(Graphics2D graphics, double centerX, double centerY, double blockSize, long elapsedMillis) {
+        long time = Math.floorMod(elapsedMillis, CYCLE_MILLIS);
+        long fadeStart = CYCLE_MILLIS - FADE_MILLIS;
+        if (time < fadeStart) {
+            drawCube(graphics, centerX, centerY, blockSize, time);
+            return;
+        }
+        fadeCube(graphics, centerX, centerY, blockSize, time, 1F - (time - fadeStart) / (float) FADE_MILLIS);
+    }
+
+    // Faded block by block, the blocks behind would show through; the whole cube is drawn first and faded as one.
+    private static void fadeCube(Graphics2D graphics, double centerX, double centerY, double blockSize, long time, float opacity) {
+        int extent = (int) Math.ceil(blockSize * (2D + DROP_HEIGHT_BLOCKS) * 2D);
+        BufferedImage cube = new BufferedImage(extent, extent, BufferedImage.TYPE_INT_ARGB);
+        Graphics2D cubeCanvas = cube.createGraphics();
+        drawCube(cubeCanvas, extent / 2D, extent / 2D, blockSize, time);
+        cubeCanvas.dispose();
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, Math.max(0F, opacity)));
+            canvas.drawImage(cube, (int) Math.round(centerX - extent / 2D), (int) Math.round(centerY - extent / 2D), null);
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private static void drawCube(Graphics2D graphics, double centerX, double centerY, double blockSize, long time) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+            for (int index = 0; index < BUILD_ORDER.length; index++) {
+                long sinceDropStart = time - (long) index * STEP_MILLIS;
+                if (sinceDropStart < 0) {
+                    break;
+                }
+                double fallen = easeOut(Math.min(1D, sinceDropStart / (double) DROP_MILLIS));
+                int[] block = BUILD_ORDER[index];
+                drawBlock(canvas, centerX, centerY, blockSize, block[0], block[1] + DROP_HEIGHT_BLOCKS * (1D - fallen), block[2]);
+            }
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private static double easeOut(double progress) {
+        double remaining = 1D - progress;
+        return 1D - remaining * remaining * remaining;
+    }
+
+    // The cube's middle, (1, 1, 1), lands on the centre point; the top and the two sides facing the viewer show.
+    private static void drawBlock(Graphics2D canvas, double centerX, double centerY, double size, double x, double y, double z) {
+        Color top = StudioTheme.ACCENT;
+        canvas.setColor(top);
+        canvas.fill(face(centerX, centerY, size, x, y, z, new double[][]{{0, 1, 0}, {1, 1, 0}, {1, 1, 1}, {0, 1, 1}}));
+        canvas.setColor(shaded(top, SIDE_SHADE));
+        canvas.fill(face(centerX, centerY, size, x, y, z, new double[][]{{1, 0, 0}, {1, 1, 0}, {1, 1, 1}, {1, 0, 1}}));
+        canvas.setColor(shaded(top, FAR_SIDE_SHADE));
+        canvas.fill(face(centerX, centerY, size, x, y, z, new double[][]{{0, 0, 1}, {1, 0, 1}, {1, 1, 1}, {0, 1, 1}}));
+    }
+
+    private static Path2D face(double centerX, double centerY, double size, double x, double y, double z, double[][] corners) {
+        Path2D path = new Path2D.Double();
+        for (int corner = 0; corner < corners.length; corner++) {
+            double cornerX = x + corners[corner][0] - 1D;
+            double cornerY = y + corners[corner][1] - 1D;
+            double cornerZ = z + corners[corner][2] - 1D;
+            double screenX = centerX + (cornerX - cornerZ) * ISOMETRIC_WIDTH * size;
+            double screenY = centerY + (cornerX + cornerZ) * ISOMETRIC_DEPTH * size - cornerY * size;
+            if (corner == 0) {
+                path.moveTo(screenX, screenY);
+            } else {
+                path.lineTo(screenX, screenY);
+            }
+        }
+        path.closePath();
+        return path;
+    }
+
+    private static Color shaded(Color color, float shade) {
+        return new Color(Math.round(color.getRed() * shade), Math.round(color.getGreen() * shade), Math.round(color.getBlue() * shade));
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapCensus.java

@@ -0,0 +1,183 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.components.MapLabels;
+import com.volmit.iris.core.gui.components.MapStyle;
+import com.volmit.iris.core.gui.components.MapTile;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.ToIntFunction;
+
+/**
+ * Measures the visible part of the map from the tiles already drawn: how much each biome or region covers, and which
+ * heights it spans.
+ */
+final class MapCensus {
+    private static final long MAXIMUM_COUNTED_PIXELS = 250_000L;
+    private static final int MINIMUM_HEIGHT_SAMPLES = 64;
+    private static final double LOW_HEIGHT_PERCENTILE = 0.01D;
+    private static final double HIGH_HEIGHT_PERCENTILE = 0.99D;
+    private static final double HEIGHT_RANGE_STEP_BLOCKS = 8D;
+    private static final double MINIMUM_WATER_DEPTH_BLOCKS = 8D;
+    private static final double MINIMUM_LAND_HEIGHT_BLOCKS = 16D;
+
+    private MapCensus() {
+    }
+
+    static List<Share> count(VisionRenderController.Frame frame, ViewArea area, ToIntFunction<MapLabels.Label> colorOf) {
+        Map<Short, long[]> counts = new HashMap<>();
+        MapLabels[] labels = new MapLabels[1];
+        long counted = visitVisiblePixels(frame, area, (tile, pixelX, pixelZ) -> {
+            labels[0] = tile.labels();
+            counts.computeIfAbsent(tile.subjectAt(pixelX, pixelZ), id -> new long[1])[0]++;
+        });
+        return shares(counts, labels[0], counted, colorOf);
+    }
+
+    /**
+     * The heights on screen, ignoring the highest and lowest few percent so one spike doesn't wash out every colour.
+     * Rounded to whole steps, so panning around doesn't recolour the map for every small change.
+     *
+     * @return the range, or null until enough of the map is drawn to tell
+     */
+    static MapStyle.HeightRange heightRange(VisionRenderController.Frame frame, ViewArea area, double seaLevel) {
+        DoubleList heights = new DoubleList();
+        visitVisiblePixels(frame, area, (tile, pixelX, pixelZ) -> {
+            if (tile.hasHeights()) {
+                heights.add(tile.heightAt(pixelX, pixelZ));
+            }
+        });
+        if (heights.size() < MINIMUM_HEIGHT_SAMPLES) {
+            return null;
+        }
+        double[] sorted = heights.sorted();
+        double low = sorted[(int) ((sorted.length - 1) * LOW_HEIGHT_PERCENTILE)];
+        double high = sorted[(int) ((sorted.length - 1) * HIGH_HEIGHT_PERCENTILE)];
+        double lowest = Math.floor(Math.min(low, seaLevel - MINIMUM_WATER_DEPTH_BLOCKS) / HEIGHT_RANGE_STEP_BLOCKS)
+                * HEIGHT_RANGE_STEP_BLOCKS;
+        double highest = Math.ceil(Math.max(high, seaLevel + MINIMUM_LAND_HEIGHT_BLOCKS) / HEIGHT_RANGE_STEP_BLOCKS)
+                * HEIGHT_RANGE_STEP_BLOCKS;
+        return new MapStyle.HeightRange(lowest, seaLevel, highest);
+    }
+
+    private static long visitVisiblePixels(VisionRenderController.Frame frame, ViewArea area, PixelVisitor visitor) {
+        if (frame == null) {
+            return 0L;
+        }
+        double blocksPerPixel = frame.renderBlocksPerPixel();
+        int stride = countingStride(area.maximumX() - area.minimumX(), area.maximumZ() - area.minimumZ(), blocksPerPixel);
+        double tileSpan = VisionRenderController.TILE_PIXELS * blocksPerPixel;
+        long visited = 0L;
+        for (VisionRenderController.VisibleTile visible : frame.tiles()) {
+            MapTile tile = visible.tile();
+            if (tile == null) {
+                continue;
+            }
+            double originX = visible.tileX() * tileSpan;
+            double originZ = visible.tileZ() * tileSpan;
+            int firstX = firstPixel(area.minimumX() - originX, blocksPerPixel, stride, visible.tileX());
+            int firstZ = firstPixel(area.minimumZ() - originZ, blocksPerPixel, stride, visible.tileZ());
+            int endX = endPixel(area.maximumX() - originX, blocksPerPixel, tile.size());
+            int endZ = endPixel(area.maximumZ() - originZ, blocksPerPixel, tile.size());
+            for (int pixelZ = firstZ; pixelZ < endZ; pixelZ += stride) {
+                for (int pixelX = firstX; pixelX < endX; pixelX += stride) {
+                    visitor.visit(tile, pixelX, pixelZ);
+                    visited++;
+                }
+            }
+        }
+        return visited;
+    }
+
+    private static List<Share> shares(Map<Short, long[]> counts, MapLabels labels, long counted,
+                                      ToIntFunction<MapLabels.Label> colorOf) {
+        if (labels == null || counted == 0L) {
+            return List.of();
+        }
+        List<Share> shares = new ArrayList<>(counts.size());
+        for (Map.Entry<Short, long[]> entry : counts.entrySet()) {
+            MapLabels.Label label = labels.label(entry.getKey());
+            if (label != null) {
+                shares.add(new Share(label, colorOf.applyAsInt(label), entry.getValue()[0] / (double) counted));
+            }
+        }
+        shares.sort(Comparator.comparingDouble(Share::fraction).reversed().thenComparing(share -> share.label().name()));
+        return List.copyOf(shares);
+    }
+
+    // Counting every pixel of a big screen is wasted work; an evenly spread sample gives the same percentages.
+    private static int countingStride(double widthBlocks, double heightBlocks, double blocksPerPixel) {
+        double pixels = (widthBlocks / blocksPerPixel) * (heightBlocks / blocksPerPixel);
+        return Math.max(1, (int) Math.ceil(Math.sqrt(pixels / MAXIMUM_COUNTED_PIXELS)));
+    }
+
+    // Starting on the global stride grid keeps neighbouring tiles from sampling the same columns twice as densely.
+    private static int firstPixel(double offsetBlocks, double blocksPerPixel, int stride, long tileIndex) {
+        int first = Math.max(0, (int) Math.ceil(offsetBlocks / blocksPerPixel));
+        long globalPixel = tileIndex * VisionRenderController.TILE_PIXELS + first;
+        int misalignment = (int) Math.floorMod(globalPixel, (long) stride);
+        return misalignment == 0 ? first : first + stride - misalignment;
+    }
+
+    private static int endPixel(double offsetBlocks, double blocksPerPixel, int size) {
+        return Math.min(size, (int) Math.ceil(offsetBlocks / blocksPerPixel));
+    }
+
+    record Share(MapLabels.Label label, int color, double fraction) {
+    }
+
+    /**
+     * The world area the screen shows, in blocks.
+     */
+    record ViewArea(double minimumX, double minimumZ, double maximumX, double maximumZ) {
+    }
+
+    @FunctionalInterface
+    private interface PixelVisitor {
+        void visit(MapTile tile, int pixelX, int pixelZ);
+    }
+
+    private static final class DoubleList {
+        private double[] values = new double[1024];
+        private int size;
+
+        void add(double value) {
+            if (size == values.length) {
+                values = Arrays.copyOf(values, size * 2);
+            }
+            values[size++] = value;
+        }
+
+        int size() {
+            return size;
+        }
+
+        double[] sorted() {
+            double[] sorted = Arrays.copyOf(values, size);
+            Arrays.sort(sorted);
+            return sorted;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapHoverCard.java

@@ -0,0 +1,503 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.MapHoverProbe.PickStep;
+import com.volmit.iris.core.gui.NoisePickSpread.Band;
+import com.volmit.iris.core.gui.components.MapLabels;
+import com.volmit.iris.core.gui.components.RenderType;
+import com.volmit.iris.core.loader.IrisRegistrant;
+import com.volmit.iris.engine.object.IrisBiome;
+
+import java.awt.Color;
+import java.awt.Font;
+import java.awt.FontMetrics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.awt.Shape;
+import java.awt.geom.RoundRectangle2D;
+import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * The card that follows the cursor, laid out like IntelliJ's documentation popup: the biome as the title, the steps
+ * that picked it as a small tree, and with Shift the terrain, location and pack files below.
+ */
+record MapHoverCard(Header header, String subtitle, String pathTitle, List<PickStep> path, boolean showsBands,
+                    List<Group> groups, List<Hint> hints) {
+    private static final int MINIMUM_CONTENT_WIDTH = 260;
+    private static final int PADDING = 12;
+    private static final int HEADER_TOP = 10;
+    private static final int HEADER_ICON_SIZE = 14;
+    private static final int NODE_ICON_SIZE = 12;
+    private static final int ICON_GAP = 8;
+    private static final int KIND_GAP = 16;
+    private static final int GROUP_GAP = 8;
+    private static final int GROUP_TITLE_GAP = 4;
+    private static final int NODE_HEIGHT = 24;
+    private static final int NODE_INDENT = 18;
+    private static final int CHIP_GAP = 16;
+    private static final int CHIP_PADDING_X = 5;
+    private static final int CHIP_PADDING_Y = 1;
+    private static final int BAND_HEIGHT = 4;
+    private static final int BAND_GAP = 6;
+    private static final int MARKER_WIDTH = 2;
+    private static final int MARKER_HEIGHT = 10;
+    private static final int COLUMN_GAP = 14;
+    private static final int ROW_GAP = 3;
+    private static final int BOTTOM_PADDING = 10;
+    private static final int FOOTER_PADDING_Y = 7;
+    private static final int KEY_PADDING_X = 4;
+    private static final int KEY_GAP = 4;
+    private static final int HINT_GAP = 14;
+    private static final Color ICON_EDGE = new ThemeColor(new Color(0, 0, 0, 38), new Color(255, 255, 255, 38));
+    private static final Color MARKER_EDGE = new Color(0, 0, 0, 200);
+
+    /**
+     * @param subject  the biome, or region in the region view, the drawn tile shows; null while that tile is drawing
+     * @param region   the region the drawn tile shows
+     * @param details  the probed facts about the spot, or null until they arrive
+     * @param detailed whether Shift is held, which trades the noise bands for terrain, location and pack files
+     */
+    static MapHoverCard of(MapLabels.Label subject, MapLabels.Label region, MapHoverProbe.Details details,
+                           RenderType type, boolean detailed, double worldX, double worldZ) {
+        List<PickStep> path = details == null ? List.of() : details.pickPath();
+        IrisBiome biome = cardBiome(subject, details, type);
+        List<Group> groups = new ArrayList<>();
+        if (detailed) {
+            addTerrainGroup(groups, details, type);
+            groups.add(locationGroup(worldX, worldZ));
+            addFilesGroup(groups, biome, details != null ? details.region() : region == null ? null : region.subject());
+        }
+        return new MapHoverCard(header(subject, biome, type, path), subtitle(details), pathTitle(path), path, !detailed,
+                groups, hints(type, detailed));
+    }
+
+    /**
+     * Draws the card with its top left corner as close to the given point as fits inside the bounds.
+     */
+    void paint(Graphics2D canvas, int anchorX, int anchorY, int boundsWidth, int boundsHeight) {
+        Graphics2D card = (Graphics2D) canvas.create();
+        card.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+        card.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+        int padding = StudioTheme.scale(PADDING);
+        int contentWidth = contentWidth(card);
+        int width = contentWidth + padding * 2;
+        int footerHeight = footerHeight(card);
+        int height = StudioTheme.scale(HEADER_TOP) + headerHeight(card) + pathHeight(card) + groupsHeight(card)
+                + StudioTheme.scale(BOTTOM_PADDING) + footerHeight;
+        int x = Math.max(padding, Math.min(boundsWidth - width - padding, anchorX));
+        int y = Math.max(padding, Math.min(boundsHeight - height - padding, anchorY));
+        StudioOverlay.drawCard(card, x, y, width, height, footerHeight);
+
+        int left = x + padding;
+        int top = y + StudioTheme.scale(HEADER_TOP);
+        top = drawHeader(card, left, top, contentWidth);
+        top = drawPath(card, left, top, contentWidth);
+        drawGroups(card, left, top);
+        drawFooter(card, left, y + height - footerHeight);
+        card.dispose();
+    }
+
+    private int contentWidth(Graphics2D canvas) {
+        int width = Math.max(headerWidth(canvas), pathWidth(canvas));
+        width = Math.max(width, groupsWidth(canvas));
+        width = Math.max(width, footerWidth(canvas));
+        return Math.max(StudioTheme.scale(MINIMUM_CONTENT_WIDTH), width);
+    }
+
+    // Header: the biome's colour, its name in bold with its kind on the right, and the ground's height below.
+    private int headerTextOffset() {
+        return header.color() == null ? 0 : StudioTheme.scale(HEADER_ICON_SIZE + ICON_GAP);
+    }
+
+    private int headerWidth(Graphics2D canvas) {
+        int width = headerTextOffset() + canvas.getFontMetrics(StudioTheme.boldFont()).stringWidth(header.name());
+        if (header.kind() != null) {
+            width += StudioTheme.scale(KIND_GAP) + canvas.getFontMetrics(StudioTheme.smallFont()).stringWidth(header.kind());
+        }
+        if (subtitle != null) {
+            width = Math.max(width, headerTextOffset() + canvas.getFontMetrics(StudioTheme.smallFont()).stringWidth(subtitle));
+        }
+        return width;
+    }
+
+    private int headerHeight(Graphics2D canvas) {
+        int height = canvas.getFontMetrics(StudioTheme.boldFont()).getHeight();
+        if (subtitle != null) {
+            height += canvas.getFontMetrics(StudioTheme.smallFont()).getHeight();
+        }
+        return height;
+    }
+
+    private int drawHeader(Graphics2D canvas, int left, int top, int contentWidth) {
+        FontMetrics bold = canvas.getFontMetrics(StudioTheme.boldFont());
+        if (header.color() != null) {
+            int iconSize = StudioTheme.scale(HEADER_ICON_SIZE);
+            drawIcon(canvas, header.color(), left, top + (bold.getHeight() - iconSize) / 2, iconSize);
+        }
+        int textLeft = left + headerTextOffset();
+        int baseline = top + bold.getAscent();
+        drawText(canvas, header.name(), StudioTheme.boldFont(), StudioTheme.TEXT, textLeft, baseline);
+        if (header.kind() != null) {
+            FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+            drawText(canvas, header.kind(), StudioTheme.smallFont(), StudioTheme.MUTED_TEXT,
+                    left + contentWidth - small.stringWidth(header.kind()), baseline);
+        }
+        top += bold.getHeight();
+        if (subtitle != null) {
+            FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+            drawText(canvas, subtitle, StudioTheme.smallFont(), StudioTheme.SECONDARY_TEXT, textLeft, top + small.getAscent());
+            top += small.getHeight();
+        }
+        return top;
+    }
+
+    // Path: one indented row per step, its value as a chip on the right and, without Shift, the noise bands below it.
+    private int pathWidth(Graphics2D canvas) {
+        int width = 0;
+        for (int level = 0; level < path.size(); level++) {
+            PickStep step = path.get(level);
+            int row = nodeTextLeft(level) + canvas.getFontMetrics(StudioTheme.font()).stringWidth(step.picked().name() + " ")
+                    + canvas.getFontMetrics(StudioTheme.smallFont()).stringWidth(step.reason());
+            if (step.value() != null) {
+                row += StudioTheme.scale(CHIP_GAP) + chipWidth(canvas, step.value());
+            }
+            width = Math.max(width, row);
+        }
+        return width;
+    }
+
+    private int pathHeight(Graphics2D canvas) {
+        if (path.isEmpty()) {
+            return 0;
+        }
+        int height = groupTitleHeight(canvas);
+        for (PickStep step : path) {
+            height += nodeHeight(step);
+        }
+        return height;
+    }
+
+    private int nodeHeight(PickStep step) {
+        int height = StudioTheme.scale(NODE_HEIGHT);
+        return showsBands && step.showsBands() ? height + StudioTheme.scale(BAND_HEIGHT + BAND_GAP) : height;
+    }
+
+    private static int nodeTextLeft(int level) {
+        return StudioTheme.scale(level * NODE_INDENT + NODE_ICON_SIZE + ICON_GAP);
+    }
+
+    private int drawPath(Graphics2D canvas, int left, int top, int contentWidth) {
+        if (path.isEmpty()) {
+            return top;
+        }
+        top = drawGroupTitle(canvas, pathTitle, left, top);
+        for (int level = 0; level < path.size(); level++) {
+            PickStep step = path.get(level);
+            drawNode(canvas, step, left, top, level, contentWidth);
+            if (showsBands && step.showsBands()) {
+                int bandsLeft = left + nodeTextLeft(level);
+                drawBands(canvas, step, bandsLeft, top + StudioTheme.scale(NODE_HEIGHT), left + contentWidth - bandsLeft);
+            }
+            top += nodeHeight(step);
+        }
+        return top;
+    }
+
+    private void drawNode(Graphics2D canvas, PickStep step, int left, int top, int level, int contentWidth) {
+        int rowHeight = StudioTheme.scale(NODE_HEIGHT);
+        int iconSize = StudioTheme.scale(NODE_ICON_SIZE);
+        drawIcon(canvas, step.picked().color(), left + StudioTheme.scale(level * NODE_INDENT), top + (rowHeight - iconSize) / 2,
+                iconSize);
+        FontMetrics regular = canvas.getFontMetrics(StudioTheme.font());
+        int baseline = top + (rowHeight - regular.getHeight()) / 2 + regular.getAscent();
+        int textLeft = left + nodeTextLeft(level);
+        String name = step.picked().name() + " ";
+        drawText(canvas, name, StudioTheme.font(), StudioTheme.TEXT, textLeft, baseline);
+        drawText(canvas, step.reason(), StudioTheme.smallFont(), StudioTheme.MUTED_TEXT, textLeft + regular.stringWidth(name),
+                baseline);
+        if (step.value() != null) {
+            drawChip(canvas, step.value(), left + contentWidth - chipWidth(canvas, step.value()), top, rowHeight);
+        }
+    }
+
+    // A strip with each option's band of noise in its colour, and a marker where this spot's noise falls.
+    private static void drawBands(Graphics2D canvas, PickStep step, int left, int top, int width) {
+        int height = StudioTheme.scale(BAND_HEIGHT);
+        Shape clip = canvas.getClip();
+        canvas.clip(new RoundRectangle2D.Double(left, top, width, height, height, height));
+        for (Band band : step.bands()) {
+            int from = left + (int) Math.round(band.fromNoise() * width);
+            int to = left + (int) Math.round(band.toNoise() * width);
+            canvas.setColor(new Color(band.option().color()));
+            canvas.fillRect(from, top, Math.max(1, to - from), height);
+        }
+        canvas.setClip(clip);
+        int markerWidth = StudioTheme.scale(MARKER_WIDTH);
+        int markerHeight = StudioTheme.scale(MARKER_HEIGHT);
+        int markerX = left + (int) Math.round(Math.clamp(step.noise(), 0D, 1D) * (width - markerWidth));
+        int markerY = top + (height - markerHeight) / 2;
+        canvas.setColor(MARKER_EDGE);
+        canvas.fillRect(markerX - 1, markerY - 1, markerWidth + 2, markerHeight + 2);
+        canvas.setColor(Color.WHITE);
+        canvas.fillRect(markerX, markerY, markerWidth, markerHeight);
+    }
+
+    private static Font chipFont() {
+        return StudioTheme.monospacedFont().deriveFont(StudioTheme.smallFont().getSize2D());
+    }
+
+    private static int chipWidth(Graphics2D canvas, String value) {
+        return canvas.getFontMetrics(chipFont()).stringWidth(value) + StudioTheme.scale(CHIP_PADDING_X) * 2;
+    }
+
+    // Styled like an inlay hint in IntelliJ's editor.
+    private static void drawChip(Graphics2D canvas, String value, int left, int rowTop, int rowHeight) {
+        FontMetrics metrics = canvas.getFontMetrics(chipFont());
+        int height = metrics.getHeight() + StudioTheme.scale(CHIP_PADDING_Y) * 2;
+        int top = rowTop + (rowHeight - height) / 2;
+        canvas.setColor(StudioTheme.HOVER_BACKGROUND);
+        int arc = StudioTheme.scale(8);
+        canvas.fillRoundRect(left, top, chipWidth(canvas, value), height, arc, arc);
+        drawText(canvas, value, chipFont(), StudioTheme.SECONDARY_TEXT, left + StudioTheme.scale(CHIP_PADDING_X),
+                top + StudioTheme.scale(CHIP_PADDING_Y) + metrics.getAscent());
+    }
+
+    private static void drawIcon(Graphics2D canvas, int rgb, int left, int top, int size) {
+        int arc = Math.max(2, size / 2);
+        canvas.setColor(new Color(rgb));
+        canvas.fillRoundRect(left, top, size, size, arc, arc);
+        canvas.setColor(ICON_EDGE);
+        canvas.drawRoundRect(left, top, size - 1, size - 1, arc, arc);
+    }
+
+    // Groups: sentence-case titles over rows of muted labels and values, all labels in one column.
+    private int labelColumnWidth(Graphics2D canvas) {
+        FontMetrics metrics = canvas.getFontMetrics(StudioTheme.font());
+        return groups.stream().flatMap(group -> group.rows().stream())
+                .mapToInt(row -> metrics.stringWidth(row.label())).max().orElse(0);
+    }
+
+    private int groupsWidth(Graphics2D canvas) {
+        FontMetrics metrics = canvas.getFontMetrics(StudioTheme.font());
+        int valueWidth = groups.stream().flatMap(group -> group.rows().stream())
+                .mapToInt(row -> metrics.stringWidth(row.value())).max().orElse(0);
+        return labelColumnWidth(canvas) + StudioTheme.scale(COLUMN_GAP) + valueWidth;
+    }
+
+    private int groupsHeight(Graphics2D canvas) {
+        int rowHeight = canvas.getFontMetrics(StudioTheme.font()).getHeight() + StudioTheme.scale(ROW_GAP);
+        return groups.stream().mapToInt(group -> groupTitleHeight(canvas) + group.rows().size() * rowHeight).sum();
+    }
+
+    private void drawGroups(Graphics2D canvas, int left, int top) {
+        FontMetrics regular = canvas.getFontMetrics(StudioTheme.font());
+        int valueLeft = left + labelColumnWidth(canvas) + StudioTheme.scale(COLUMN_GAP);
+        for (Group group : groups) {
+            top = drawGroupTitle(canvas, group.title(), left, top);
+            for (Row row : group.rows()) {
+                int baseline = top + regular.getAscent();
+                drawText(canvas, row.label(), StudioTheme.font(), StudioTheme.SECONDARY_TEXT, left, baseline);
+                drawText(canvas, row.value(), StudioTheme.font(), row.link() ? StudioTheme.LINK : StudioTheme.TEXT, valueLeft,
+                        baseline);
+                top += regular.getHeight() + StudioTheme.scale(ROW_GAP);
+            }
+        }
+    }
+
+    private static int groupTitleHeight(Graphics2D canvas) {
+        return StudioTheme.scale(GROUP_GAP) + canvas.getFontMetrics(StudioTheme.smallFont()).getHeight()
+                + StudioTheme.scale(GROUP_TITLE_GAP);
+    }
+
+    private static int drawGroupTitle(Graphics2D canvas, String title, int left, int top) {
+        FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+        top += StudioTheme.scale(GROUP_GAP);
+        drawText(canvas, title, StudioTheme.smallFont(), StudioTheme.MUTED_TEXT, left, top + small.getAscent());
+        return top + small.getHeight() + StudioTheme.scale(GROUP_TITLE_GAP);
+    }
+
+    // Footer: the shortcuts as key caps, each followed by what it does.
+    private int footerWidth(Graphics2D canvas) {
+        FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+        int width = 0;
+        for (Hint hint : hints) {
+            width += keyWidth(small, hint.key()) + StudioTheme.scale(KEY_GAP) + small.stringWidth(hint.action());
+        }
+        return width + StudioTheme.scale(HINT_GAP) * Math.max(0, hints.size() - 1);
+    }
+
+    private static int footerHeight(Graphics2D canvas) {
+        return canvas.getFontMetrics(StudioTheme.smallFont()).getHeight() + StudioTheme.scale(FOOTER_PADDING_Y) * 2;
+    }
+
+    private static int keyWidth(FontMetrics small, String key) {
+        return small.stringWidth(key) + StudioTheme.scale(KEY_PADDING_X) * 2;
+    }
+
+    private void drawFooter(Graphics2D canvas, int left, int top) {
+        FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+        int textTop = top + StudioTheme.scale(FOOTER_PADDING_Y);
+        int baseline = textTop + small.getAscent();
+        int arc = StudioTheme.scale(6);
+        for (Hint hint : hints) {
+            int keyWidth = keyWidth(small, hint.key());
+            canvas.setColor(StudioTheme.HOVER_BACKGROUND);
+            canvas.fillRoundRect(left, textTop, keyWidth, small.getHeight(), arc, arc);
+            drawText(canvas, hint.key(), StudioTheme.smallFont(), StudioTheme.SECONDARY_TEXT,
+                    left + StudioTheme.scale(KEY_PADDING_X), baseline);
+            left += keyWidth + StudioTheme.scale(KEY_GAP);
+            drawText(canvas, hint.action(), StudioTheme.smallFont(), StudioTheme.MUTED_TEXT, left, baseline);
+            left += small.stringWidth(hint.action()) + StudioTheme.scale(HINT_GAP);
+        }
+    }
+
+    private static void drawText(Graphics2D canvas, String text, Font font, Color color, int left, int baseline) {
+        canvas.setFont(font);
+        canvas.setColor(color);
+        canvas.drawString(text, left, baseline);
+    }
+
+    // The card is about a biome; the region view's tiles only know the region until the probe finds the biome.
+    private static IrisBiome cardBiome(MapLabels.Label subject, MapHoverProbe.Details details, RenderType type) {
+        if (subject != null && subject.subject() instanceof IrisBiome biome) {
+            return biome;
+        }
+        if (details == null) {
+            return null;
+        }
+        return type == RenderType.CAVE_LAND ? details.caveBiome() : details.surfaceBiome();
+    }
+
+    private static Header header(MapLabels.Label subject, IrisBiome biome, RenderType type, List<PickStep> path) {
+        if (biome != null) {
+            return new Header(biome.getName(), colorOf(biome, path), type == RenderType.CAVE_LAND ? "Cave biome" : "Biome");
+        }
+        if (subject != null) {
+            return new Header(subject.name(), null, subject.kind() == MapLabels.Kind.REGION ? "Region" : "Biome");
+        }
+        return new Header("Drawing…", null, null);
+    }
+
+    private static Integer colorOf(IrisBiome biome, List<PickStep> path) {
+        return path.stream()
+                .filter(step -> step.picked().key().equals(biome.getLoadKey()))
+                .reduce((first, last) -> last)
+                .map(step -> step.picked().color())
+                .orElse(null);
+    }
+
+    private static String subtitle(MapHoverProbe.Details details) {
+        if (details == null) {
+            return null;
+        }
+        return Math.round(details.height()) + " · " + heightAboveSea(details.height() - details.fluidHeight()) + " · slope "
+                + Math.round(details.slopeDegrees()) + "°";
+    }
+
+    private static String pathTitle(List<PickStep> path) {
+        return path.size() > 1 ? "Picked by" : "Region";
+    }
+
+    private static void addTerrainGroup(List<Group> groups, MapHoverProbe.Details details, RenderType type) {
+        if (details == null) {
+            return;
+        }
+        List<Row> rows = new ArrayList<>();
+        IrisBiome surface = details.surfaceBiome();
+        IrisBiome cave = details.caveBiome();
+        if (type == RenderType.CAVE_LAND && surface != null) {
+            rows.add(new Row("Surface biome", surface.getName(), false));
+        } else if (type != RenderType.CAVE_LAND && cave != null && cave != surface) {
+            rows.add(new Row("Cave biome", cave.getName(), false));
+        }
+        if (details.vanillaBiome() != null) {
+            rows.add(new Row("Minecraft", details.vanillaBiome().replace('_', ' '), false));
+        }
+        if (!rows.isEmpty()) {
+            groups.add(new Group("Terrain", rows));
+        }
+    }
+
+    private static Group locationGroup(double worldX, double worldZ) {
+        int blockX = MapCanvas.floorWorldCoordinate(worldX);
+        int blockZ = MapCanvas.floorWorldCoordinate(worldZ);
+        return new Group("Location", List.of(
+                new Row("Block", blockX + ", " + blockZ, false),
+                new Row("Chunk", (blockX >> 4) + ", " + (blockZ >> 4), false),
+                new Row("Region file", "r." + (blockX >> 9) + "." + (blockZ >> 9) + ".mca", false)));
+    }
+
+    private static void addFilesGroup(List<Group> groups, IrisBiome biome, Object region) {
+        List<Row> rows = new ArrayList<>();
+        if (biome != null) {
+            rows.add(new Row("Biome", packPath(biome), true));
+        }
+        if (region instanceof IrisRegistrant registrant) {
+            rows.add(new Row("Region", packPath(registrant), true));
+        }
+        if (!rows.isEmpty()) {
+            groups.add(new Group("Files", rows));
+        }
+    }
+
+    // The key is the path under the type's folder, so folder, key and extension give the file within the pack.
+    private static String packPath(IrisRegistrant registrant) {
+        File file = registrant.getLoadFile();
+        String fileName = file == null ? "" : file.getName();
+        int extensionStart = fileName.lastIndexOf('.');
+        String extension = extensionStart < 0 ? "" : fileName.substring(extensionStart);
+        return registrant.getFolderName() + "/" + registrant.getLoadKey() + extension;
+    }
+
+    private static List<Hint> hints(RenderType type, boolean detailed) {
+        List<Hint> hints = new ArrayList<>();
+        if (!detailed) {
+            hints.add(new Hint("Shift", "More"));
+        }
+        hints.add(new Hint("H", "Highlight"));
+        if (type != RenderType.CONTINENT) {
+            hints.add(new Hint("Alt+Click", "Open file"));
+        }
+        return hints;
+    }
+
+    private static String heightAboveSea(double height) {
+        long rounded = Math.round(height);
+        return rounded < 0 ? -rounded + " below sea" : rounded + " above sea";
+    }
+
+    /**
+     * @param color the biome's map colour, or null when no step of the path tells it
+     * @param kind  what the title names, like "Biome", or null while drawing
+     */
+    record Header(String name, Integer color, String kind) {
+    }
+
+    record Group(String title, List<Row> rows) {
+    }
+
+    record Row(String label, String value, boolean link) {
+    }
+
+    record Hint(String key, String action) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapHoverProbe.java

@@ -0,0 +1,178 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.NoisePickSpread.Band;
+import com.volmit.iris.core.gui.NoisePickSpread.Option;
+import com.volmit.iris.engine.HybridBiomeSelector;
+import com.volmit.iris.engine.IrisComplex;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.InferredType;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisDimension;
+import com.volmit.iris.engine.object.IrisRegion;
+import org.bukkit.block.Biome;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * Looks up everything the hover card can tell about one spot of the world; runs off the Swing thread.
+ */
+final class MapHoverProbe {
+    // IrisComplex measures slope as the height change over this many blocks.
+    private static final double SLOPE_STREAM_RANGE_BLOCKS = 3D;
+
+    private MapHoverProbe() {
+    }
+
+    /**
+     * @param previewRegionKey the region the region preview treats every spot as part of, or null for the real world
+     * @param explainBiomePick whether the card shows the surface biome, so the whole way to it is worth looking up;
+     *                         otherwise only how the region was picked
+     */
+    static Details sample(Engine engine, double worldX, double worldZ, String previewRegionKey, boolean explainBiomePick) {
+        IrisComplex complex = engine.getComplex();
+        IrisRegion previewRegion = previewRegionKey == null ? null : engine.getData().getRegionLoader().load(previewRegionKey);
+        IrisRegion region = previewRegion != null ? previewRegion : complex.getRegionStream().get(worldX, worldZ);
+        IrisComplex.BiomePick surfacePick = complex.surfacePickAsIfIn(region, worldX, worldZ);
+        Biome vanillaBiome = complex.getTrueBiomeDerivativeStream().get(worldX, worldZ);
+        double slope = complex.getSlopeStream().getDouble(worldX, worldZ);
+        IrisDimension dimension = engine.getDimension();
+        return new Details(
+                worldX,
+                worldZ,
+                surfacePick.biome(),
+                complex.getCaveBiomeStream().get(worldX, worldZ),
+                region,
+                vanillaBiome == null ? null : vanillaBiome.getKey().getKey(),
+                complex.getHeightStream().getDouble(worldX, worldZ),
+                dimension == null ? 0D : dimension.getFluidHeight(),
+                Math.toDegrees(Math.atan(slope / SLOPE_STREAM_RANGE_BLOCKS)),
+                pickPath(engine, region, previewRegion != null, explainBiomePick ? surfacePick : null, worldX, worldZ)
+        );
+    }
+
+    // The region preview chose the region itself; the real map picks it by the region noise.
+    private static List<PickStep> pickPath(Engine engine, IrisRegion region, boolean previewed,
+                                           IrisComplex.BiomePick surfacePick, double x, double z) {
+        List<PickStep> path = new ArrayList<>();
+        path.add(previewed ? previewedRegionStep(engine, region) : regionStep(engine, region, x, z));
+        if (surfacePick == null || surfacePick.type() == null || engine.getComplex().getFocusBiome() != null) {
+            return path;
+        }
+        PickStep biomeStep = engine.getComplex().isHybridTerrain()
+                ? heightStep(engine, region, surfacePick.type(), x, z)
+                : noiseStep(engine, region, surfacePick.type(), x, z);
+        if (biomeStep == null) {
+            return path;
+        }
+        path.add(biomeStep);
+        if (!biomeStep.picked().key().equals(surfacePick.biome().getLoadKey())) {
+            path.add(new PickStep(PickMeasuring.biomeOption(engine, surfacePick.biome()), "child", null, List.of(), Double.NaN));
+        }
+        return path;
+    }
+
+    private static PickStep regionStep(Engine engine, IrisRegion region, double x, double z) {
+        IrisComplex complex = engine.getComplex();
+        double noise = complex.getRegionStyleStream().get(x, z);
+        List<Option> regions = complex.noisePickedRegions().stream()
+                .map(candidate -> PickMeasuring.regionOption(engine, candidate))
+                .toList();
+        return new PickStep(PickMeasuring.regionOption(engine, region), "region", noiseText(noise),
+                NoisePickSpread.splitNoise(regions, complex.isLegacyRarity()), noise);
+    }
+
+    private static PickStep previewedRegionStep(Engine engine, IrisRegion region) {
+        return new PickStep(PickMeasuring.regionOption(engine, region), "previewed", null, List.of(), Double.NaN);
+    }
+
+    private static PickStep noiseStep(Engine engine, IrisRegion region, InferredType type, double x, double z) {
+        IrisComplex complex = engine.getComplex();
+        double noise = complex.biomePickNoise(region, type, x, z);
+        List<Option> biomes = complex.noisePickedBiomes(region, type).stream()
+                .map(biome -> PickMeasuring.biomeOption(engine, biome))
+                .toList();
+        IrisBiome picked = complex.biomePickedByNoise(region, type, x, z);
+        return new PickStep(PickMeasuring.biomeOption(engine, picked), typeName(type), noiseText(noise),
+                NoisePickSpread.splitNoise(biomes, complex.isLegacyRarity()), noise);
+    }
+
+    // HYBRID terrain picks by the height a spot is placed at, and only competes where biome ranges share that height.
+    private static PickStep heightStep(Engine engine, IrisRegion region, InferredType type, double x, double z) {
+        HybridBiomeSelector.Choice choice = engine.getComplex().explainHybridChoice(region, type, x, z);
+        if (choice == null) {
+            return null;
+        }
+        return new PickStep(PickMeasuring.biomeOption(engine, choice.biome()), typeName(type) + ", " + competitionText(choice),
+                signedHeightText(choice.placementHeight()), List.of(), Double.NaN);
+    }
+
+    private static String competitionText(HybridBiomeSelector.Choice choice) {
+        if (choice.fallback()) {
+            return "nearest range";
+        }
+        if (choice.rivalCount() == 0) {
+            return "only fit";
+        }
+        return "beat " + choice.rivalCount();
+    }
+
+    private static String typeName(InferredType type) {
+        return type.name().toLowerCase(Locale.ROOT);
+    }
+
+    private static String noiseText(double noise) {
+        return String.format(Locale.ROOT, "%.3f", noise);
+    }
+
+    private static String signedHeightText(double heightAboveSea) {
+        long rounded = Math.round(heightAboveSea);
+        return rounded < 0 ? "−" + -rounded : "+" + rounded;
+    }
+
+    record Details(
+            double worldX,
+            double worldZ,
+            IrisBiome surfaceBiome,
+            IrisBiome caveBiome,
+            IrisRegion region,
+            String vanillaBiome,
+            double height,
+            double fluidHeight,
+            double slopeDegrees,
+            List<PickStep> pickPath
+    ) {
+    }
+
+    /**
+     * One step on the way to the spot's biome, starting with its region.
+     *
+     * @param reason what picked it: its kind, the biome list the noise picked from, or "child"
+     * @param value  the noise value or placement height that picked it, or null
+     * @param bands  the noise bands of all the options the noise picked from, empty when no noise picked it
+     */
+    record PickStep(Option picked, String reason, String value, List<Band> bands, double noise) {
+        boolean showsBands() {
+            return !bands.isEmpty();
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapLegendPanel.java

@@ -0,0 +1,230 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.components.MapStyle;
+
+import javax.swing.BorderFactory;
+import javax.swing.DefaultListCellRenderer;
+import javax.swing.DefaultListModel;
+import javax.swing.JLabel;
+import javax.swing.JList;
+import javax.swing.JPanel;
+import javax.swing.ListSelectionModel;
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Point;
+import java.awt.Rectangle;
+import java.awt.RenderingHints;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Set;
+import java.util.function.Consumer;
+
+/**
+ * The biomes or regions on screen with how much of it each covers; clicking one highlights it on the map.
+ */
+final class MapLegendPanel extends JPanel {
+    private static final long serialVersionUID = 4471297416386034128L;
+    private static final int PANEL_WIDTH = 250;
+    private static final int ROW_HEIGHT = 26;
+    private static final int SWATCH_SIZE = 12;
+    private static final int SWATCH_GAP = 8;
+    private static final int ROW_PADDING = 10;
+    private static final int PERCENT_WIDTH = 42;
+    private static final String DRAWING_MESSAGE = "Drawing the map…";
+
+    private final JLabel title = new JLabel();
+    private final DefaultListModel<MapCensus.Share> rows = new DefaultListModel<>();
+    private final JList<MapCensus.Share> list = new JList<>(rows) {
+        // Long names shorten with an ellipsis instead of pushing the percentages out of sight.
+        @Override
+        public boolean getScrollableTracksViewportWidth() {
+            return true;
+        }
+    };
+    private final Set<String> sharedNames = new HashSet<>();
+    private MapStyle.Highlight highlight;
+
+    MapLegendPanel(Consumer<MapCensus.Share> onRowClicked) {
+        super(new BorderLayout());
+        setPreferredSize(StudioTheme.scaledSize(PANEL_WIDTH, 0));
+        setBorder(BorderFactory.createMatteBorder(0, 1, 0, 0, StudioTheme.SEPARATOR));
+        setBackground(StudioTheme.PANEL_BACKGROUND);
+
+        title.setFont(StudioTheme.sectionFont());
+        title.setForeground(StudioTheme.MUTED_TEXT);
+        title.setBorder(StudioTheme.emptyBorder(10, 16, 6, 16));
+        add(title, BorderLayout.NORTH);
+
+        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
+        list.setFocusable(false);
+        list.setFixedCellHeight(StudioTheme.scale(ROW_HEIGHT));
+        list.setCellRenderer(new ShareRenderer());
+        list.setBackground(StudioTheme.PANEL_BACKGROUND);
+        list.setBorder(StudioTheme.emptyBorder(0, 6, 4, 6));
+        list.addMouseListener(new MouseAdapter() {
+            @Override
+            public void mouseClicked(MouseEvent event) {
+                MapCensus.Share share = shareAt(event.getPoint());
+                if (share != null) {
+                    onRowClicked.accept(share);
+                }
+            }
+        });
+        add(StudioToolbar.scroll(list), BorderLayout.CENTER);
+
+        JLabel hint = new JLabel("Click to highlight · Esc clears");
+        hint.setFont(StudioTheme.smallFont());
+        hint.setForeground(StudioTheme.MUTED_TEXT);
+        hint.setBorder(StudioTheme.emptyBorder(6, 16, 8, 16));
+        add(hint, BorderLayout.SOUTH);
+    }
+
+    void show(String subjectTitle, List<MapCensus.Share> shares, MapStyle.Highlight nextHighlight) {
+        title.setText(subjectTitle.toUpperCase(Locale.ROOT));
+        highlight = nextHighlight;
+        rememberSharedNames(shares);
+        if (!sameRows(shares)) {
+            rows.clear();
+            rows.addAll(shares);
+        }
+        list.repaint();
+    }
+
+    // Two biomes can share a display name; those rows show their key so they can be told apart.
+    private void rememberSharedNames(List<MapCensus.Share> shares) {
+        Set<String> seen = new HashSet<>();
+        sharedNames.clear();
+        for (MapCensus.Share share : shares) {
+            if (!seen.add(share.label().name())) {
+                sharedNames.add(share.label().name());
+            }
+        }
+    }
+
+    private String rowText(MapCensus.Share share) {
+        String name = share.label().name();
+        return sharedNames.contains(name) ? name + " (" + share.label().key() + ")" : name;
+    }
+
+    private boolean sameRows(List<MapCensus.Share> shares) {
+        if (rows.size() != shares.size()) {
+            return false;
+        }
+        for (int index = 0; index < shares.size(); index++) {
+            if (!rows.get(index).equals(shares.get(index))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private MapCensus.Share shareAt(Point point) {
+        int index = list.locationToIndex(point);
+        if (index < 0) {
+            return null;
+        }
+        Rectangle bounds = list.getCellBounds(index, index);
+        return bounds != null && bounds.contains(point) ? rows.get(index) : null;
+    }
+
+    private boolean isHighlighted(MapCensus.Share share) {
+        return highlight != null
+                && highlight.kind() == share.label().kind()
+                && highlight.key().equals(share.label().key());
+    }
+
+    @Override
+    protected void paintChildren(Graphics graphics) {
+        super.paintChildren(graphics);
+        if (!rows.isEmpty()) {
+            return;
+        }
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+            canvas.setFont(StudioTheme.font());
+            canvas.setColor(StudioTheme.MUTED_TEXT);
+            canvas.drawString(DRAWING_MESSAGE, StudioTheme.scale(16),
+                    title.getHeight() + StudioTheme.scale(4) + canvas.getFontMetrics().getAscent());
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private final class ShareRenderer extends DefaultListCellRenderer {
+        private static final long serialVersionUID = -2350212934617052618L;
+        private Color swatch = Color.BLACK;
+        private String percent = "";
+
+        @Override
+        public Component getListCellRendererComponent(JList<?> owner, Object value, int index, boolean selected, boolean focused) {
+            MapCensus.Share share = (MapCensus.Share) value;
+            super.getListCellRendererComponent(owner, rowText(share), index, isHighlighted(share), false);
+            setFont(StudioTheme.font());
+            setBorder(StudioTheme.emptyBorder(0, ROW_PADDING + SWATCH_SIZE + SWATCH_GAP, 0, ROW_PADDING + PERCENT_WIDTH));
+            setToolTipText(share.label().key());
+            swatch = new Color(share.color());
+            percent = formatPercent(share.fraction());
+            return this;
+        }
+
+        @Override
+        protected void paintComponent(Graphics graphics) {
+            super.paintComponent(graphics);
+            Graphics2D canvas = (Graphics2D) graphics.create();
+            try {
+                canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+                canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+                int size = StudioTheme.scale(SWATCH_SIZE);
+                int swatchX = StudioTheme.scale(ROW_PADDING);
+                int swatchY = (getHeight() - size) / 2;
+                int arc = StudioTheme.scale(4);
+                canvas.setColor(swatch);
+                canvas.fillRoundRect(swatchX, swatchY, size, size, arc, arc);
+                canvas.setColor(StudioTheme.CONTROL_BORDER);
+                canvas.drawRoundRect(swatchX, swatchY, size - 1, size - 1, arc, arc);
+                canvas.setFont(StudioTheme.smallFont());
+                canvas.setColor(StudioTheme.SECONDARY_TEXT);
+                int textWidth = canvas.getFontMetrics().stringWidth(percent);
+                int baseline = (getHeight() + canvas.getFontMetrics().getAscent() - canvas.getFontMetrics().getDescent()) / 2;
+                canvas.drawString(percent, getWidth() - StudioTheme.scale(ROW_PADDING) - textWidth, baseline);
+            } finally {
+                canvas.dispose();
+            }
+        }
+    }
+
+    private static String formatPercent(double fraction) {
+        double percent = fraction * 100D;
+        if (percent < 0.1D) {
+            return "<0.1%";
+        }
+        return percent < 10D
+                ? String.format(Locale.ROOT, "%.1f%%", percent)
+                : String.format(Locale.ROOT, "%.0f%%", percent);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapView.java

@@ -0,0 +1,119 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.components.RenderType;
+
+import java.awt.event.KeyEvent;
+
+/**
+ * Everything the map window can show, in the order and groups of its view list.
+ */
+enum MapView {
+    BIOMES("Biomes", "The biome at each spot, in the biome's colour", Group.WORLD, RenderType.BIOME, KeyEvent.VK_1),
+    REGIONS("Regions", "The region each spot belongs to; pick one to see which biome covers which height",
+            Group.WORLD, RenderType.REGION, KeyEvent.VK_2),
+    HEIGHT("Height", "Terrain height, from deep water to snowy peaks", Group.WORLD, RenderType.HEIGHT, KeyEvent.VK_3),
+    CONTINENTS("Continents", "Land, coast or sea: where hybrid terrain ends up, or each biome's first height generator otherwise",
+            Group.WORLD, RenderType.CONTINENT, KeyEvent.VK_4),
+    LAND_BIOMES("Land biomes", "The land biome each spot would get, also where the sea is",
+            Group.BIOME_STREAMS, RenderType.BIOME_LAND, KeyEvent.VK_5),
+    SEA_BIOMES("Sea biomes", "The sea biome each spot would get, also where the land is",
+            Group.BIOME_STREAMS, RenderType.BIOME_SEA, KeyEvent.VK_6),
+    CAVE_BIOMES("Cave biomes", "The cave biome under each spot", Group.BIOME_STREAMS, RenderType.CAVE_LAND, KeyEvent.VK_7),
+    PALETTES("Palettes", "The blocks each biome's palette layers place, with their textures",
+            Group.BLOCKS, null, KeyEvent.VK_P),
+    OBJECTS("Objects", "Every object in the pack in 3D, with the blocks it is made of",
+            Group.BLOCKS, null, KeyEvent.VK_O),
+    PROCEDURAL("Procedural", "Trees, rock formations and more that Iris generates from settings, every variant in 3D",
+            Group.BLOCKS, null, KeyEvent.VK_T),
+    NOISE("Noise", "The pack's noise generators and Iris' built-in noise styles",
+            Group.GENERATORS, null, KeyEvent.VK_N);
+
+    private final String label;
+    private final String description;
+    private final Group group;
+    private final RenderType renderType;
+    private final int shortcutKey;
+
+    MapView(String label, String description, Group group, RenderType renderType, int shortcutKey) {
+        this.label = label;
+        this.description = description;
+        this.group = group;
+        this.renderType = renderType;
+        this.shortcutKey = shortcutKey;
+    }
+
+    String label() {
+        return label;
+    }
+
+    String description() {
+        return description;
+    }
+
+    Group group() {
+        return group;
+    }
+
+    /**
+     * The tile renderer's mode for this view, or null for the palette, object, procedural and noise views, which draw themselves.
+     */
+    RenderType renderType() {
+        return renderType;
+    }
+
+    int shortcutKey() {
+        return shortcutKey;
+    }
+
+    String shortcutText() {
+        return KeyEvent.getKeyText(shortcutKey);
+    }
+
+    boolean isTileMap() {
+        return renderType != null;
+    }
+
+    static MapView forShortcut(int keyCode) {
+        for (MapView view : values()) {
+            if (view.shortcutKey == keyCode) {
+                return view;
+            }
+        }
+        return null;
+    }
+
+    enum Group {
+        WORLD("World"),
+        BIOME_STREAMS("Biome layers"),
+        BLOCKS("Blocks"),
+        GENERATORS("Generators");
+
+        private final String label;
+
+        Group(String label) {
+            this.label = label;
+        }
+
+        String label() {
+            return label;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapViewIcon.java

@@ -0,0 +1,54 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.formdev.flatlaf.extras.FlatSVGIcon;
+
+import javax.swing.Icon;
+import java.util.EnumMap;
+import java.util.Locale;
+import java.util.Map;
+
+/**
+ * The icon of each map view, taken from IntelliJ's new UI icon set (see the NOTICE next to the files).
+ */
+final class MapViewIcon {
+    private static final String ICON_FOLDER = "iris/icons/views/";
+    private static final int SIZE = 16;
+    private static final Map<MapView, Icon> LOADED = new EnumMap<>(MapView.class);
+
+    private MapViewIcon() {
+    }
+
+    static Icon of(MapView view) {
+        return LOADED.computeIfAbsent(view, shown -> load(shown, SIZE));
+    }
+
+    /**
+     * The view's icon drawn larger, for an empty view.
+     */
+    static Icon large(MapView view, int size) {
+        return load(view, size);
+    }
+
+    private static Icon load(MapView view, int size) {
+        String fileName = view.name().toLowerCase(Locale.ROOT).replace('_', '-') + ".svg";
+        return new FlatSVGIcon(ICON_FOLDER + fileName, size, size, MapViewIcon.class.getClassLoader());
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapViewList.java

@@ -0,0 +1,246 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.DefaultListCellRenderer;
+import javax.swing.DefaultListModel;
+import javax.swing.JList;
+import javax.swing.ListSelectionModel;
+import javax.swing.UIManager;
+import java.awt.Component;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Insets;
+import java.awt.Rectangle;
+import java.awt.RenderingHints;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.util.Locale;
+import java.util.function.Consumer;
+
+/**
+ * The map window's list of views, grouped under headers, each row with a picture of the view and the key that opens
+ * it.
+ */
+final class MapViewList extends JList<MapViewList.Row> {
+    private static final long serialVersionUID = -4130872409914437415L;
+    private static final int ROW_HEIGHT = 28;
+    private static final int NO_ROW = -1;
+
+    private final DefaultListModel<Row> rows = new DefaultListModel<>();
+    private int lastViewRow;
+    private int hoveredRow = NO_ROW;
+
+    MapViewList(Consumer<MapView> onViewChosen) {
+        fillRows();
+        setModel(rows);
+        setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
+        setFixedCellHeight(StudioTheme.scale(ROW_HEIGHT));
+        setCellRenderer(new RowRenderer());
+        setBorder(StudioTheme.emptyBorder(4, 6, 4, 6));
+        addListSelectionListener(event -> {
+            if (event.getValueIsAdjusting() || skipHeaderRow()) {
+                return;
+            }
+            Row selected = getSelectedValue();
+            if (selected == null) {
+                return;
+            }
+            lastViewRow = getSelectedIndex();
+            onViewChosen.accept(selected.view());
+        });
+        MouseAdapter hover = new MouseAdapter() {
+            @Override
+            public void mouseMoved(MouseEvent event) {
+                hover(viewRowAt(event));
+            }
+
+            @Override
+            public void mouseExited(MouseEvent event) {
+                hover(NO_ROW);
+            }
+        };
+        addMouseListener(hover);
+        addMouseMotionListener(hover);
+    }
+
+    private int viewRowAt(MouseEvent event) {
+        int row = locationToIndex(event.getPoint());
+        if (row < 0 || rows.get(row).isHeader() || !getCellBounds(row, row).contains(event.getPoint())) {
+            return NO_ROW;
+        }
+        return row;
+    }
+
+    private void hover(int row) {
+        if (row == hoveredRow) {
+            return;
+        }
+        repaintRow(hoveredRow);
+        hoveredRow = row;
+        repaintRow(hoveredRow);
+    }
+
+    private void repaintRow(int row) {
+        Rectangle bounds = row == NO_ROW ? null : getCellBounds(row, row);
+        if (bounds != null) {
+            repaint(bounds);
+        }
+    }
+
+    void select(MapView view) {
+        for (int row = 0; row < rows.size(); row++) {
+            if (rows.get(row).view() == view) {
+                lastViewRow = row;
+                setSelectedIndex(row);
+                ensureIndexIsVisible(row);
+                return;
+            }
+        }
+    }
+
+    private void fillRows() {
+        MapView.Group currentGroup = null;
+        for (MapView view : MapView.values()) {
+            if (view.group() != currentGroup) {
+                currentGroup = view.group();
+                rows.addElement(Row.header(currentGroup));
+            }
+            rows.addElement(Row.of(view));
+        }
+    }
+
+    // Headers can't be chosen: clicking one keeps the current view, and the arrow keys carry on past it.
+    private boolean skipHeaderRow() {
+        int row = getSelectedIndex();
+        if (row < 0 || !rows.get(row).isHeader()) {
+            return false;
+        }
+        int step = row >= lastViewRow ? 1 : -1;
+        int next = nextViewRow(row, step);
+        if (next < 0) {
+            next = nextViewRow(row, -step);
+        }
+        setSelectedIndex(next < 0 ? lastViewRow : next);
+        ensureIndexIsVisible(getSelectedIndex());
+        return true;
+    }
+
+    private int nextViewRow(int from, int step) {
+        for (int row = from + step; row >= 0 && row < rows.size(); row += step) {
+            if (!rows.get(row).isHeader()) {
+                return row;
+            }
+        }
+        return -1;
+    }
+
+    record Row(MapView.Group group, MapView view) {
+        static Row header(MapView.Group group) {
+            return new Row(group, null);
+        }
+
+        static Row of(MapView view) {
+            return new Row(view.group(), view);
+        }
+
+        boolean isHeader() {
+            return view == null;
+        }
+    }
+
+    private static final class RowRenderer extends DefaultListCellRenderer {
+        private static final long serialVersionUID = 6302156810211578474L;
+        private static final int ICON_TEXT_GAP = 8;
+        private static final int KEYCAP_SIZE = 17;
+        private static final int KEYCAP_ARC = 5;
+        private String shortcut;
+        private boolean hovered;
+
+        @Override
+        public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean selected, boolean focused) {
+            Row row = (Row) value;
+            super.getListCellRendererComponent(list, row.isHeader() ? "" : row.view().label(), index, selected && !row.isHeader(), false);
+            if (row.isHeader()) {
+                setText(row.group().label().toUpperCase(Locale.ROOT));
+                setFont(StudioTheme.sectionFont());
+                setForeground(StudioTheme.MUTED_TEXT);
+                setBorder(StudioTheme.emptyBorder(index == 0 ? 2 : 10, 8, 0, 6));
+                setIcon(null);
+                setToolTipText(null);
+                shortcut = null;
+                hovered = false;
+                setOpaque(true);
+                return this;
+            }
+            setFont(StudioTheme.font());
+            setBorder(StudioTheme.emptyBorder(0, 8, 0, 8));
+            setIcon(MapViewIcon.of(row.view()));
+            setIconTextGap(StudioTheme.scale(ICON_TEXT_GAP));
+            setToolTipText(row.view().description());
+            shortcut = row.view().shortcutText();
+            hovered = !selected && list instanceof MapViewList viewList && viewList.hoveredRow == index;
+            setOpaque(!hovered);
+            return this;
+        }
+
+        @Override
+        protected void paintComponent(Graphics graphics) {
+            Graphics2D canvas = (Graphics2D) graphics.create();
+            try {
+                canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+                canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+                if (hovered) {
+                    paintHoverBackground(canvas);
+                }
+                super.paintComponent(graphics);
+                if (shortcut != null) {
+                    paintKeycap(canvas);
+                }
+            } finally {
+                canvas.dispose();
+            }
+        }
+
+        // Shaped like the selection the look and feel paints, so moving between them doesn't jump.
+        private void paintHoverBackground(Graphics2D canvas) {
+            Insets inset = UIManager.getInsets("List.selectionInsets");
+            int left = inset == null ? 0 : StudioTheme.scale(inset.left);
+            int right = inset == null ? 0 : StudioTheme.scale(inset.right);
+            int arc = StudioTheme.scale(UIManager.getInt("List.selectionArc"));
+            canvas.setColor(StudioTheme.HOVER_BACKGROUND);
+            canvas.fillRoundRect(left, 0, getWidth() - left - right, getHeight(), arc, arc);
+        }
+
+        private void paintKeycap(Graphics2D canvas) {
+            canvas.setFont(StudioTheme.smallFont());
+            int textWidth = canvas.getFontMetrics().stringWidth(shortcut);
+            int height = StudioTheme.scale(KEYCAP_SIZE);
+            int width = Math.max(height, textWidth + StudioTheme.scale(8));
+            int x = getWidth() - getInsets().right - width;
+            int y = (getHeight() - height) / 2;
+            int arc = StudioTheme.scale(KEYCAP_ARC);
+            canvas.setColor(StudioTheme.CONTROL_BORDER);
+            canvas.drawRoundRect(x, y, width - 1, height - 1, arc, arc);
+            canvas.setColor(StudioTheme.SECONDARY_TEXT);
+            int baseline = y + (height + canvas.getFontMetrics().getAscent() - canvas.getFontMetrics().getDescent()) / 2;
+            canvas.drawString(shortcut, x + (width - textWidth) / 2, baseline);
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapWindow.java

@@ -0,0 +1,555 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.components.MapStyle;
+
+import javax.swing.AbstractAction;
+import javax.swing.BorderFactory;
+import javax.swing.Box;
+import javax.swing.JComponent;
+import javax.swing.JFrame;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JRootPane;
+import javax.swing.JSplitPane;
+import javax.swing.JToggleButton;
+import javax.swing.JToolBar;
+import javax.swing.KeyStroke;
+import javax.swing.SwingConstants;
+import javax.swing.text.JTextComponent;
+import java.awt.BorderLayout;
+import java.awt.CardLayout;
+import java.awt.Dimension;
+import java.awt.EventQueue;
+import java.awt.KeyboardFocusManager;
+import java.awt.event.ActionEvent;
+import java.awt.event.ComponentAdapter;
+import java.awt.event.ComponentEvent;
+import java.awt.event.KeyEvent;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
+import java.util.ArrayList;
+import java.util.EnumMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.IntConsumer;
+
+/**
+ * The studio map: one window showing the world as tiles in several views, with the palette, object and noise explorers
+ * as its Palettes, Objects and Noise views.
+ */
+public final class MapWindow implements MapCanvas.Listener {
+    private static final String MAP_CARD = "map";
+    private static final String PALETTES_CARD = "palettes";
+    private static final String NOISE_CARD = "noise";
+    private static final int SIDEBAR_WIDTH = 270;
+    private static final int SIDEBAR_MINIMUM_WIDTH = 200;
+    private static final int CONTENT_MINIMUM_WIDTH = 320;
+    private static final double PALETTE_RECENTER_DISTANCE_BLOCKS = 1D;
+    private static final int VIEW_LIST_SCROLL_INSETS = 4;
+    private static final int EXPLORER_DIVIDER_HEIGHT = 7;
+
+    private final JFrame frame;
+    private final PaletteExplorerStart start;
+    private final MapCanvas canvas;
+    private final MapViewList viewList;
+    private final JLabel viewTitle = new JLabel();
+    private final JPanel content = new JPanel(new CardLayout());
+    private final JPanel statusBars = new JPanel(new CardLayout());
+    private final JPanel sidebar = new JPanel(new BorderLayout());
+    private final IslandPanel sidebarIsland = new IslandPanel(sidebar);
+    private final JPanel inspectorSlot = new JPanel(new BorderLayout());
+    private final JComponent viewListScroll;
+    private final JSplitPane explorerSplit = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
+    private final JSplitPane pickInspectorSplit = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
+    private final List<JComponent> mapControls = new ArrayList<>();
+    private final List<JComponent> explorerControls = new ArrayList<>();
+    private final List<JComponent> noiseControls = new ArrayList<>();
+    private final JToolBar toolbar = StudioToolbar.create();
+    private final JComponent resetViewButton = StudioToolbar.button("Reset view", "Go back to the starting position and zoom (R)",
+            this::resetExplorerView);
+    private final JToggleButton gridToggle = StudioToolbar.toggle("Grid", "Show chunk and region borders (G)");
+    private final JToggleButton entitiesToggle = StudioToolbar.toggle("Entities", "Show mobs and other entities (E)");
+    private final JToggleButton followToggle = StudioToolbar.toggle("Follow", "Keep your player in the middle (F)");
+    private final JToggleButton shadingToggle = StudioToolbar.toggle("Shading", "Shade hills and valleys on every view (S)");
+    private final JToggleButton bordersToggle = StudioToolbar.toggle("Borders", "Outline the regions on every view (B)");
+    private final MapLegendPanel legendPanel;
+    private final RegionExplorer regionExplorer;
+    private final BiomeExplorer biomeExplorer;
+
+    private NoiseExplorerGUI paletteExplorer;
+    private final Map<MapView, ObjectExplorer> objectExplorers = new EnumMap<>(MapView.class);
+    private NoiseExplorerGUI noiseExplorer;
+    private JComponent noiseSidebar;
+    private MapView currentView;
+    private double paletteCenterX;
+    private double paletteCenterZ;
+
+    private MapWindow(PaletteExplorerStart start) {
+        this.start = start;
+        this.frame = GuiHost.createFrame("Iris Map");
+        this.canvas = new MapCanvas(start.engine(), start.worldId(), start.playerId(), this);
+        this.viewList = new MapViewList(this::showView);
+        this.viewListScroll = StudioToolbar.scroll(viewList);
+        this.legendPanel = new MapLegendPanel(share -> canvas.toggleHighlight(share.label()));
+        this.regionExplorer = new RegionExplorer(canvas::engine, canvas::previewRegion, canvas::showPicksAs);
+        this.biomeExplorer = new BiomeExplorer(canvas::engine, canvas::showPicksAs);
+        canvas.centerOn(start.centerX(), start.centerZ());
+        buildFrame();
+    }
+
+    public static void openMap(PaletteExplorerStart start) {
+        EventQueue.invokeLater(() -> open(start, MapView.BIOMES));
+    }
+
+    public static void openPalettes(PaletteExplorerStart start) {
+        EventQueue.invokeLater(() -> open(start, MapView.PALETTES));
+    }
+
+    public static void openNoise(PaletteExplorerStart start) {
+        EventQueue.invokeLater(() -> open(start, MapView.NOISE));
+    }
+
+    private static void open(PaletteExplorerStart start, MapView initialView) {
+        StudioTheme.install();
+        MapWindow window = new MapWindow(start);
+        window.frame.setVisible(true);
+        window.canvas.start();
+        window.showView(initialView);
+    }
+
+    private void buildFrame() {
+        styleExplorerSplit();
+        stylePickInspectorSplit();
+        content.add(canvas, MAP_CARD);
+        statusBars.add(canvas.statusBar(), MAP_CARD);
+        sidebar.add(viewListScroll, BorderLayout.CENTER);
+
+        frame.setLayout(new BorderLayout());
+        frame.add(buildToolbar(), BorderLayout.NORTH);
+        frame.add(new IslandOverlay(sidebarIsland, content, StudioTheme.scale(SIDEBAR_WIDTH),
+                StudioTheme.scale(SIDEBAR_MINIMUM_WIDTH), StudioTheme.scale(CONTENT_MINIMUM_WIDTH)), BorderLayout.CENTER);
+        frame.add(inspectorSlot, BorderLayout.EAST);
+        frame.add(statusBars, BorderLayout.SOUTH);
+        installShortcuts(frame.getRootPane());
+        keepClearOfIsland(canvas::setCoveredLeftWidth);
+        frame.setSize(GuiHost.fitToScreen(StudioTheme.scaledSize(1440, 880)));
+        frame.setMinimumSize(StudioTheme.scaledSize(820, 520));
+        frame.setLocationRelativeTo(null);
+        frame.addWindowListener(new WindowAdapter() {
+            @Override
+            public void windowClosed(WindowEvent event) {
+                close();
+            }
+        });
+    }
+
+    private JToolBar buildToolbar() {
+        viewTitle.setFont(StudioTheme.titleFont());
+        viewTitle.setBorder(StudioTheme.emptyBorder(0, 6, 0, 14));
+        toolbar.add(viewTitle);
+
+        mapControls.add(StudioToolbar.button("Refresh", "Redraw the map with the latest pack files (R)", canvas::refreshContent));
+        mapControls.add(StudioToolbar.button("Reset zoom", "Go back to the default zoom (\\)", canvas::resetZoom));
+        mapControls.add(gridToggle);
+        mapControls.add(entitiesToggle);
+        mapControls.add(followToggle);
+        mapControls.add(toolbarSeparator());
+        mapControls.add(shadingToggle);
+        mapControls.add(bordersToggle);
+        gridToggle.addActionListener(event -> canvas.toggleGrid());
+        entitiesToggle.addActionListener(event -> canvas.toggleEntities());
+        followToggle.addActionListener(event -> canvas.toggleFollow());
+        shadingToggle.addActionListener(event -> canvas.toggleShading());
+        bordersToggle.addActionListener(event -> canvas.toggleRegionBorders());
+        mapControls.forEach(toolbar::add);
+
+        explorerControls.add(resetViewButton);
+        explorerControls.forEach(toolbar::add);
+
+        toolbar.add(Box.createHorizontalGlue());
+        toolbar.add(StudioToolbar.themeButton());
+        JComponent help = StudioToolbar.button("Shortcuts", "Show every mouse and key shortcut (/)", canvas::toggleHelp);
+        mapControls.add(help);
+        toolbar.add(help);
+        return toolbar;
+    }
+
+    private static JComponent toolbarSeparator() {
+        JToolBar.Separator separator = new JToolBar.Separator();
+        separator.setOrientation(SwingConstants.VERTICAL);
+        return separator;
+    }
+
+    private void showView(MapView view) {
+        if (view == null || view == currentView) {
+            return;
+        }
+        MapView previousView = currentView;
+        currentView = view;
+        viewList.select(view);
+        viewTitle.setText(view.label());
+        viewTitle.setToolTipText(view.description());
+        if (view.isTileMap()) {
+            showMap(previousView, view);
+        } else if (view == MapView.PALETTES) {
+            showPalettes(previousView);
+        } else if (view == MapView.OBJECTS || view == MapView.PROCEDURAL) {
+            showObjectExplorer(view);
+        } else {
+            showNoise();
+        }
+        frame.getRootPane().revalidate();
+        frame.getRootPane().repaint();
+    }
+
+    private void showMap(MapView previousView, MapView view) {
+        if (previousView == MapView.PALETTES && paletteExplorer != null) {
+            canvas.centerOn(paletteExplorer.centerX(), paletteExplorer.centerZ());
+        }
+        canvas.showView(view);
+        canvas.setActive(true);
+        showControls(mapControls);
+        inspectorSlot.removeAll();
+        if (view == MapView.REGIONS) {
+            showRegionExplorer(previousView);
+        } else if (view == MapView.BIOMES) {
+            showBiomeExplorer();
+        } else {
+            useSidebar(viewListScroll);
+            inspectorSlot.add(legendPanel, BorderLayout.CENTER);
+        }
+        showCard(MAP_CARD);
+        canvas.requestFocusInWindow();
+    }
+
+    // The region inspector sits above the legend, which then lists the chosen region's biomes on the map.
+    private void showRegionExplorer(MapView previousView) {
+        if (previousView != MapView.REGIONS) {
+            regionExplorer.loadRegions();
+        }
+        useSidebar(viewListAbove(regionExplorer.navigator()));
+        showPickInspector(regionExplorer.inspector());
+        EventQueue.invokeLater(() -> viewList.select(currentView));
+        regionExplorer.measure(canvas.viewArea());
+    }
+
+    private void showBiomeExplorer() {
+        useSidebar(viewListScroll);
+        showPickInspector(biomeExplorer.inspector());
+        biomeExplorer.measure(canvas.viewArea());
+    }
+
+    // The region and biome views share how the map draws its picks, so their switches show the same choice.
+    private void showPickInspector(PickInspectorPanel inspector) {
+        inspector.selectDisplay(canvas.pickDisplay());
+        pickInspectorSplit.setTopComponent(inspector);
+        pickInspectorSplit.setBottomComponent(legendPanel);
+        inspectorSlot.add(pickInspectorSplit, BorderLayout.CENTER);
+    }
+
+    private void stylePickInspectorSplit() {
+        pickInspectorSplit.setBorder(BorderFactory.createMatteBorder(0, 1, 0, 0, StudioTheme.SEPARATOR));
+        pickInspectorSplit.setResizeWeight(0.7D);
+        pickInspectorSplit.setBackground(StudioTheme.PANEL_BACKGROUND);
+        pickInspectorSplit.setDividerSize(StudioTheme.scale(EXPLORER_DIVIDER_HEIGHT));
+        pickInspectorSplit.putClientProperty("FlatLaf.style", "style: grip");
+    }
+
+    private void showPalettes(MapView previousView) {
+        boolean firstOpen = paletteExplorer == null;
+        if (firstOpen) {
+            createPaletteExplorer(previousView == null);
+        } else {
+            followMapIntoPalettes();
+        }
+        canvas.setActive(false);
+        showControls(explorerControls);
+        useSidebar(viewListAbove(paletteExplorer.paletteSidebar()));
+        inspectorSlot.removeAll();
+        inspectorSlot.add(paletteExplorer.paletteInspector(), BorderLayout.CENTER);
+        showCard(PALETTES_CARD);
+        EventQueue.invokeLater(() -> viewList.select(currentView));
+        if (firstOpen) {
+            paletteExplorer.openViewer();
+        }
+    }
+
+    private void showObjectExplorer(MapView view) {
+        boolean firstOpen = !objectExplorers.containsKey(view);
+        ObjectExplorer explorer = objectExplorers.computeIfAbsent(view, this::createObjectExplorer);
+        canvas.setActive(false);
+        showControls(explorerControls);
+        useSidebar(viewListAbove(explorer.browser()));
+        inspectorSlot.removeAll();
+        inspectorSlot.add(explorer.overview(), BorderLayout.CENTER);
+        showCard(view.name());
+        EventQueue.invokeLater(() -> viewList.select(currentView));
+        if (firstOpen) {
+            explorer.open();
+        }
+    }
+
+    private void keepClearOfIsland(IntConsumer setCoveredLeftWidth) {
+        setCoveredLeftWidth.accept(sidebarIsland.getWidth());
+        sidebarIsland.addComponentListener(new ComponentAdapter() {
+            @Override
+            public void componentResized(ComponentEvent event) {
+                setCoveredLeftWidth.accept(sidebarIsland.getWidth());
+            }
+        });
+    }
+
+    private ObjectExplorer createObjectExplorer(MapView view) {
+        ObjectSource source = view == MapView.PROCEDURAL ? new ProceduralObjectSource() : new PackObjectSource();
+        ObjectExplorer explorer = new ObjectExplorer(start.engine(), start.worldId(), source);
+        keepClearOfIsland(explorer::setCoveredLeftWidth);
+        content.add(explorer.view(), view.name());
+        statusBars.add(explorer.statusBar(), view.name());
+        return explorer;
+    }
+
+    private void showNoise() {
+        boolean firstOpen = noiseExplorer == null;
+        if (firstOpen) {
+            createNoiseExplorer();
+        }
+        canvas.setActive(false);
+        showControls(noiseControls, explorerControls);
+        useSidebar(viewListAbove(noiseSidebar));
+        inspectorSlot.removeAll();
+        showCard(NOISE_CARD);
+        EventQueue.invokeLater(() -> viewList.select(currentView));
+        if (firstOpen) {
+            noiseExplorer.openViewer();
+        }
+    }
+
+    // Both explorers share one split, so the divider stays where it was dragged when switching between them.
+    private JSplitPane viewListAbove(JComponent explorerSidebar) {
+        boolean firstUse = explorerSplit.getBottomComponent() == null;
+        explorerSplit.setTopComponent(viewListScroll);
+        explorerSplit.setBottomComponent(explorerSidebar);
+        if (firstUse) {
+            EventQueue.invokeLater(this::fitViewListAboveExplorer);
+        }
+        return explorerSplit;
+    }
+
+    private void styleExplorerSplit() {
+        explorerSplit.setBorder(BorderFactory.createEmptyBorder());
+        explorerSplit.setResizeWeight(0D);
+        explorerSplit.setBackground(StudioTheme.PANEL_BACKGROUND);
+        explorerSplit.setDividerSize(StudioTheme.scale(EXPLORER_DIVIDER_HEIGHT));
+        explorerSplit.putClientProperty("FlatLaf.style", "style: grip");
+    }
+
+    // Every view stays in sight, so the divider starts below the last one and can only be dragged further down. Measured
+    // once the sidebar is laid out, since the list's rows are taller before they know their width.
+    private void fitViewListAboveExplorer() {
+        int fullHeight = viewList.getPreferredSize().height + VIEW_LIST_SCROLL_INSETS;
+        viewListScroll.setMinimumSize(new Dimension(0, fullHeight));
+        explorerSplit.setDividerLocation(fullHeight);
+    }
+
+    private void createNoiseExplorer() {
+        noiseExplorer = NoiseExplorerGUI.createNoiseExplorer(start.engine());
+        noiseSidebar = noiseExplorer.noiseSidebar();
+        noiseControls.addAll(noiseExplorer.noiseControls());
+        noiseControls.forEach(control -> toolbar.add(control, toolbar.getComponentIndex(resetViewButton)));
+        content.add(noiseExplorer, NOISE_CARD);
+        statusBars.add(noiseExplorer.statusBar(), NOISE_CARD);
+    }
+
+    private void createPaletteExplorer(boolean openedOnPalettes) {
+        PaletteExplorerStart explorerStart = openedOnPalettes
+                ? start
+                : new PaletteExplorerStart(start.engine(), start.worldId(), start.playerId(), null, canvas.centerX(), canvas.centerZ());
+        paletteExplorer = NoiseExplorerGUI.createPaletteExplorer(explorerStart);
+        content.add(paletteExplorer, PALETTES_CARD);
+        statusBars.add(paletteExplorer.statusBar(), PALETTES_CARD);
+        rememberPaletteCenter(explorerStart.centerX(), explorerStart.centerZ());
+        if (!openedOnPalettes) {
+            showSurfaceBiomePalettes(explorerStart.centerX(), explorerStart.centerZ());
+        }
+    }
+
+    // Coming back from the map only moves the palettes when the map was moved, so a chosen layer survives a quick look.
+    private void followMapIntoPalettes() {
+        double movedX = canvas.centerX() - paletteCenterX;
+        double movedZ = canvas.centerZ() - paletteCenterZ;
+        if (Math.hypot(movedX, movedZ) < PALETTE_RECENTER_DISTANCE_BLOCKS) {
+            return;
+        }
+        paletteExplorer.centerOn(canvas.centerX(), canvas.centerZ());
+        rememberPaletteCenter(canvas.centerX(), canvas.centerZ());
+        showSurfaceBiomePalettes(canvas.centerX(), canvas.centerZ());
+    }
+
+    @Override
+    public void onShowPalettesAt(double worldX, double worldZ) {
+        canvas.centerOn(worldX, worldZ);
+        showView(MapView.PALETTES);
+    }
+
+    private void showSurfaceBiomePalettes(double worldX, double worldZ) {
+        canvas.findSurfaceBiome(worldX, worldZ, biomeKey -> {
+            if (paletteExplorer != null) {
+                paletteExplorer.showPalettesAt(worldX, worldZ, biomeKey);
+            }
+        });
+    }
+
+    private void rememberPaletteCenter(double worldX, double worldZ) {
+        paletteCenterX = worldX;
+        paletteCenterZ = worldZ;
+    }
+
+    @Override
+    public void onTogglesChanged() {
+        gridToggle.setSelected(canvas.isGridVisible());
+        entitiesToggle.setSelected(canvas.areEntitiesVisible());
+        followToggle.setSelected(canvas.isFollowing());
+        shadingToggle.setSelected(canvas.style().shading());
+        bordersToggle.setSelected(canvas.style().regionBorders());
+    }
+
+    @Override
+    public void onLegendChanged(String title, List<MapCensus.Share> shares, MapStyle.Highlight highlight) {
+        legendPanel.show(title, shares, highlight);
+        if (currentView == MapView.REGIONS) {
+            regionExplorer.measure(canvas.viewArea());
+        } else if (currentView == MapView.BIOMES) {
+            biomeExplorer.measure(canvas.viewArea());
+        }
+    }
+
+    @Override
+    public void onContentRefreshed() {
+        regionExplorer.refresh();
+        biomeExplorer.refresh();
+    }
+
+    private void resetExplorerView() {
+        ObjectExplorer objectExplorer = objectExplorers.get(currentView);
+        if (objectExplorer != null) {
+            objectExplorer.resetCamera();
+            return;
+        }
+        NoiseExplorerGUI explorer = currentView == MapView.NOISE ? noiseExplorer : paletteExplorer;
+        if (explorer != null) {
+            explorer.resetViewport();
+        }
+    }
+
+    private void useSidebar(JComponent component) {
+        sidebar.removeAll();
+        sidebar.add(component, BorderLayout.CENTER);
+    }
+
+    private void showCard(String card) {
+        ((CardLayout) content.getLayout()).show(content, card);
+        ((CardLayout) statusBars.getLayout()).show(statusBars, card);
+    }
+
+    @SafeVarargs
+    private void showControls(List<JComponent>... visibleControls) {
+        for (List<JComponent> controls : List.of(mapControls, explorerControls, noiseControls)) {
+            controls.forEach(control -> control.setVisible(false));
+        }
+        for (List<JComponent> controls : visibleControls) {
+            controls.forEach(control -> control.setVisible(true));
+        }
+    }
+
+    private void installShortcuts(JRootPane rootPane) {
+        for (MapView view : MapView.values()) {
+            bind(rootPane, KeyStroke.getKeyStroke(view.shortcutKey(), 0), "view-" + view.name(), () -> showView(view));
+        }
+        bind(rootPane, KeyStroke.getKeyStroke(KeyEvent.VK_M, 0), "next-view", this::showNextView);
+        bind(rootPane, KeyStroke.getKeyStroke(KeyEvent.VK_R, 0), "refresh", this::refreshOrReset);
+        bindMap(rootPane, KeyEvent.VK_F, 0, "follow", canvas::toggleFollow);
+        bindMap(rootPane, KeyEvent.VK_G, 0, "grid", canvas::toggleGrid);
+        bindMap(rootPane, KeyEvent.VK_E, 0, "entities", canvas::toggleEntities);
+        bindMap(rootPane, KeyEvent.VK_F3, 0, "debug", canvas::toggleDebug);
+        bindMap(rootPane, KeyEvent.VK_H, 0, "highlight", canvas::highlightUnderCursor);
+        bindMap(rootPane, KeyEvent.VK_ESCAPE, 0, "dismiss", canvas::dismissEmphasis);
+        bindMap(rootPane, KeyEvent.VK_S, 0, "shading", canvas::toggleShading);
+        bindMap(rootPane, KeyEvent.VK_B, 0, "borders", canvas::toggleRegionBorders);
+        bindMap(rootPane, KeyEvent.VK_EQUALS, 0, "zoom-in", canvas::zoomIn);
+        bindMap(rootPane, KeyEvent.VK_EQUALS, KeyEvent.SHIFT_DOWN_MASK, "zoom-in-plus", canvas::zoomIn);
+        bindMap(rootPane, KeyEvent.VK_ADD, 0, "zoom-in-keypad", canvas::zoomIn);
+        bindMap(rootPane, KeyEvent.VK_MINUS, 0, "zoom-out", canvas::zoomOut);
+        bindMap(rootPane, KeyEvent.VK_SUBTRACT, 0, "zoom-out-keypad", canvas::zoomOut);
+        bindMap(rootPane, KeyEvent.VK_BACK_SLASH, 0, "reset-zoom", canvas::resetZoom);
+        bindMap(rootPane, KeyEvent.VK_SLASH, 0, "help", canvas::toggleHelp);
+        bindMap(rootPane, KeyEvent.VK_SLASH, KeyEvent.SHIFT_DOWN_MASK, "help-question", canvas::toggleHelp);
+        bind(rootPane, KeyStroke.getKeyStroke(KeyEvent.VK_SHIFT, KeyEvent.SHIFT_DOWN_MASK, false), "details-on",
+                () -> canvas.setDetailedHover(true));
+        bind(rootPane, KeyStroke.getKeyStroke(KeyEvent.VK_SHIFT, 0, true), "details-off", () -> canvas.setDetailedHover(false));
+    }
+
+    private void bindMap(JRootPane rootPane, int keyCode, int modifiers, String name, Runnable action) {
+        bind(rootPane, KeyStroke.getKeyStroke(keyCode, modifiers), name, () -> {
+            if (currentView != null && currentView.isTileMap()) {
+                action.run();
+            }
+        });
+    }
+
+    // Keys typed into a search box belong to that box, not to the window's shortcuts.
+    private static void bind(JRootPane rootPane, KeyStroke keyStroke, String name, Runnable action) {
+        rootPane.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(keyStroke, name);
+        rootPane.getActionMap().put(name, new AbstractAction() {
+            @Override
+            public void actionPerformed(ActionEvent event) {
+                if (!(KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner() instanceof JTextComponent)) {
+                    action.run();
+                }
+            }
+        });
+    }
+
+    private void showNextView() {
+        MapView[] views = MapView.values();
+        showView(views[(currentView.ordinal() + 1) % views.length]);
+    }
+
+    private void refreshOrReset() {
+        if (currentView.isTileMap()) {
+            canvas.refreshContent();
+        } else {
+            resetExplorerView();
+        }
+    }
+
+    private void close() {
+        canvas.close();
+        regionExplorer.close();
+        biomeExplorer.close();
+        if (paletteExplorer != null) {
+            paletteExplorer.close();
+        }
+        objectExplorers.values().forEach(ObjectExplorer::close);
+        if (noiseExplorer != null) {
+            noiseExplorer.close();
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MinecraftBiomeColors.java

@@ -0,0 +1,155 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.volmit.iris.engine.object.IrisBiomeCustom;
+import org.bukkit.NamespacedKey;
+
+import java.awt.Color;
+import java.awt.image.BufferedImage;
+import java.io.IOException;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.zip.ZipFile;
+
+// Works out biome tint colours the way Minecraft does, from the colour maps and vanilla biome files in the client jar.
+final class MinecraftBiomeColors {
+    private static final String COLOR_MAP_FOLDER = "assets/minecraft/textures/colormap/";
+    private static final int COLOR_MAP_SIZE = 256;
+    private static final int GRASS_FALLBACK = 0xFF00FF;
+    private static final int FOLIAGE_FALLBACK = 0x48B518;
+    private static final int DRY_FOLIAGE_FALLBACK = 0x5C3C32;
+    private static final float UNKNOWN_BIOME_TEMPERATURE = 0.5F;
+    private static final float UNKNOWN_BIOME_DOWNFALL = 0.5F;
+    private static final int UNKNOWN_BIOME_WATER = 0x3F76E4;
+    private static final int UNPARSEABLE_COLOR = 0x000000;
+
+    private final ZipFile clientJar;
+    private final ColorMap grassMap;
+    private final ColorMap foliageMap;
+    private final ColorMap dryFoliageMap;
+    private final Map<NamespacedKey, BiomeTintColors> vanillaBiomes = new ConcurrentHashMap<>();
+
+    private MinecraftBiomeColors(ZipFile clientJar, ColorMap grassMap, ColorMap foliageMap, ColorMap dryFoliageMap) {
+        this.clientJar = clientJar;
+        this.grassMap = grassMap;
+        this.foliageMap = foliageMap;
+        this.dryFoliageMap = dryFoliageMap;
+    }
+
+    static MinecraftBiomeColors load(ZipFile clientJar) throws IOException {
+        return new MinecraftBiomeColors(
+                clientJar,
+                ColorMap.read(clientJar, "grass.png", GRASS_FALLBACK),
+                ColorMap.read(clientJar, "foliage.png", FOLIAGE_FALLBACK),
+                ColorMap.read(clientJar, "dry_foliage.png", DRY_FOLIAGE_FALLBACK)
+        );
+    }
+
+    BiomeTintColors vanilla(NamespacedKey biome) {
+        return vanillaBiomes.computeIfAbsent(biome, this::readVanillaBiome);
+    }
+
+    // Iris registers custom biomes as data pack biomes built from these fields, see IrisBiomeCustom#generateJson.
+    BiomeTintColors custom(IrisBiomeCustom biome) {
+        float temperature = (float) biome.getTemperature();
+        float downfall = (float) biome.getHumidity();
+        return new BiomeTintColors(
+                biome.getGrassColor().isEmpty() ? grassMap.colorAt(temperature, downfall) : parseIrisColor(biome.getGrassColor()),
+                BiomeTintColors.GrassColorModifier.NONE,
+                biome.getFoliageColor().isEmpty() ? foliageMap.colorAt(temperature, downfall) : parseIrisColor(biome.getFoliageColor()),
+                dryFoliageMap.colorAt(temperature, downfall),
+                parseIrisColor(biome.getWaterColor())
+        );
+    }
+
+    private BiomeTintColors readVanillaBiome(NamespacedKey biome) {
+        JsonObject definition = readBiomeDefinition(biome);
+        if (definition == null) {
+            return fromClimate(UNKNOWN_BIOME_TEMPERATURE, UNKNOWN_BIOME_DOWNFALL, new JsonObject());
+        }
+        JsonObject effects = definition.has("effects") ? definition.getAsJsonObject("effects") : new JsonObject();
+        return fromClimate(definition.get("temperature").getAsFloat(), definition.get("downfall").getAsFloat(), effects);
+    }
+
+    private BiomeTintColors fromClimate(float temperature, float downfall, JsonObject effects) {
+        return new BiomeTintColors(
+                effects.has("grass_color") ? parseVanillaColor(effects.get("grass_color")) : grassMap.colorAt(temperature, downfall),
+                effects.has("grass_color_modifier")
+                        ? BiomeTintColors.GrassColorModifier.named(effects.get("grass_color_modifier").getAsString())
+                        : BiomeTintColors.GrassColorModifier.NONE,
+                effects.has("foliage_color") ? parseVanillaColor(effects.get("foliage_color")) : foliageMap.colorAt(temperature, downfall),
+                effects.has("dry_foliage_color") ? parseVanillaColor(effects.get("dry_foliage_color")) : dryFoliageMap.colorAt(temperature, downfall),
+                effects.has("water_color") ? parseVanillaColor(effects.get("water_color")) : UNKNOWN_BIOME_WATER
+        );
+    }
+
+    private JsonObject readBiomeDefinition(NamespacedKey biome) {
+        try {
+            return ClientJarFiles.readJson(clientJar, "data/" + biome.getNamespace() + "/worldgen/biome/" + biome.getKey() + ".json");
+        } catch (IOException | RuntimeException error) {
+            return null;
+        }
+    }
+
+    // Older versions store colours as plain numbers, newer ones as "#rrggbb" strings.
+    private static int parseVanillaColor(JsonElement color) {
+        if (color.getAsJsonPrimitive().isNumber()) {
+            return color.getAsInt() & 0xFFFFFF;
+        }
+        return Integer.parseInt(color.getAsString().substring(1), 16);
+    }
+
+    private static int parseIrisColor(String color) {
+        try {
+            return Color.decode((color.startsWith("#") ? color : "#" + color).trim()).getRGB() & 0xFFFFFF;
+        } catch (RuntimeException error) {
+            return UNPARSEABLE_COLOR;
+        }
+    }
+
+    // Minecraft's ColorMapColorUtil: temperature picks the column and temperature times downfall picks the row.
+    private record ColorMap(int[] pixels, int fallback) {
+        private static ColorMap read(ZipFile clientJar, String name, int fallback) throws IOException {
+            BufferedImage image = ClientJarFiles.readImage(clientJar, COLOR_MAP_FOLDER + name);
+            if (image == null) {
+                throw new IOException("Minecraft colour map " + name + " is missing");
+            }
+            int[] pixels = new int[COLOR_MAP_SIZE * COLOR_MAP_SIZE];
+            for (int y = 0; y < COLOR_MAP_SIZE; y++) {
+                for (int x = 0; x < COLOR_MAP_SIZE; x++) {
+                    pixels[y * COLOR_MAP_SIZE + x] = image.getRGB(x, y) & 0xFFFFFF;
+                }
+            }
+            return new ColorMap(pixels, fallback);
+        }
+
+        private int colorAt(float temperature, float downfall) {
+            double clampedTemperature = Math.clamp(temperature, 0F, 1F);
+            double clampedDownfall = Math.clamp(downfall, 0F, 1F) * clampedTemperature;
+            int x = (int) ((1D - clampedTemperature) * 255D);
+            int y = (int) ((1D - clampedDownfall) * 255D);
+            int index = y << 8 | x;
+            return index >= pixels.length ? fallback : pixels[index];
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MinecraftBlockTints.java

@@ -0,0 +1,85 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+
+// Mirrors Minecraft's BlockColors: which colour each tinted face of a block is multiplied with in the world.
+final class MinecraftBlockTints {
+    static final int NO_TINT = 0xFFFFFF;
+    private static final Set<String> GRASS_TINTED = Set.of(
+            "grass_block", "short_grass", "fern", "potted_fern", "bush", "tall_grass", "large_fern", "sugar_cane");
+    private static final Set<String> GRASS_TINTED_ON_SECOND_LAYER = Set.of("pink_petals", "wildflowers");
+    private static final Set<String> FOLIAGE_TINTED = Set.of(
+            "oak_leaves", "jungle_leaves", "acacia_leaves", "dark_oak_leaves", "vine", "mangrove_leaves");
+    private static final Set<String> WATER_TINTED_BY_FLUID_RENDERER = Set.of("water", "bubble_column");
+    private static final Set<String> GROWING_STEMS = Set.of("melon_stem", "pumpkin_stem");
+    private static final Map<String, Integer> FIXED_TINTS = Map.of(
+            "spruce_leaves", 0x619961,
+            "birch_leaves", 0x80A755,
+            "attached_melon_stem", 0xE0C71C,
+            "attached_pumpkin_stem", 0xE0C71C,
+            "lily_pad", 0x208030
+    );
+
+    private MinecraftBlockTints() {
+    }
+
+    static Optional<BiomeTint> biomeTint(String blockName, int tintIndex) {
+        if (WATER_TINTED_BY_FLUID_RENDERER.contains(blockName)) {
+            return Optional.of(BiomeTint.WATER);
+        }
+        if (GRASS_TINTED_ON_SECOND_LAYER.contains(blockName)) {
+            return tintIndex == 1 ? Optional.of(BiomeTint.GRASS) : Optional.empty();
+        }
+        if (tintIndex != 0) {
+            return Optional.empty();
+        }
+        if (GRASS_TINTED.contains(blockName)) {
+            return Optional.of(BiomeTint.GRASS);
+        }
+        if (FOLIAGE_TINTED.contains(blockName)) {
+            return Optional.of(BiomeTint.FOLIAGE);
+        }
+        if (blockName.equals("leaf_litter")) {
+            return Optional.of(BiomeTint.DRY_FOLIAGE);
+        }
+        if (blockName.equals("water_cauldron")) {
+            return Optional.of(BiomeTint.WATER);
+        }
+        return Optional.empty();
+    }
+
+    static int fixedTint(String blockName, Map<String, String> properties, int tintIndex) {
+        if (tintIndex != 0) {
+            return NO_TINT;
+        }
+        if (GROWING_STEMS.contains(blockName)) {
+            return stemTint(Integer.parseInt(properties.getOrDefault("age", "0")));
+        }
+        return FIXED_TINTS.getOrDefault(blockName, NO_TINT);
+    }
+
+    private static int stemTint(int age) {
+        return (age * 32) << 16 | (255 - age * 8) << 8 | (age * 4);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MinecraftClientJar.java

@@ -0,0 +1,145 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.volmit.iris.Iris;
+import org.bukkit.Bukkit;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.security.DigestInputStream;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.time.Duration;
+import java.util.HexFormat;
+import java.util.concurrent.CompletableFuture;
+import java.util.zip.ZipFile;
+
+final class MinecraftClientJar {
+    private static final URI VERSION_MANIFEST = URI.create("https://piston-meta.mojang.com/mc/game/version_manifest_v2.json");
+    private static final Duration CONNECT_TIMEOUT = Duration.ofSeconds(15);
+    private static final Duration DOWNLOAD_TIMEOUT = Duration.ofMinutes(10);
+    private static final HttpClient HTTP = HttpClient.newBuilder()
+            .connectTimeout(CONNECT_TIMEOUT)
+            .followRedirects(HttpClient.Redirect.NORMAL)
+            .build();
+
+    private MinecraftClientJar() {
+    }
+
+    static boolean isCached() {
+        return cachedJar().exists();
+    }
+
+    static CompletableFuture<ZipFile> open() {
+        return CompletableFuture.supplyAsync(() -> {
+            try {
+                File jar = cachedJar();
+                if (!jar.exists()) {
+                    download(Bukkit.getMinecraftVersion(), jar.toPath());
+                }
+                return new ZipFile(jar);
+            } catch (IOException | InterruptedException error) {
+                throw new IllegalStateException(readableReason(error), error);
+            }
+        }, MinecraftClientJar::runInBackground);
+    }
+
+    private static void runInBackground(Runnable task) {
+        Thread thread = new Thread(task, "Iris Minecraft Client Download");
+        thread.setDaemon(true);
+        thread.start();
+    }
+
+    private static File cachedJar() {
+        return Iris.instance.getDataFile("cache", "minecraft-client", Bukkit.getMinecraftVersion() + ".jar");
+    }
+
+    private static void download(String version, Path destination) throws IOException, InterruptedException {
+        JsonObject versionInfo = fetchJson(findVersionUrl(version));
+        JsonObject client = versionInfo.getAsJsonObject("downloads").getAsJsonObject("client");
+        URI clientUrl = URI.create(client.get("url").getAsString());
+        String expectedSha1 = client.get("sha1").getAsString();
+
+        Path partial = destination.resolveSibling(destination.getFileName() + ".part");
+        HttpResponse<InputStream> response = HTTP.send(
+                HttpRequest.newBuilder(clientUrl).timeout(DOWNLOAD_TIMEOUT).build(),
+                HttpResponse.BodyHandlers.ofInputStream()
+        );
+        requireSuccess(response.statusCode(), clientUrl);
+        String actualSha1;
+        try (DigestInputStream body = new DigestInputStream(response.body(), sha1())) {
+            Files.copy(body, partial, StandardCopyOption.REPLACE_EXISTING);
+            actualSha1 = HexFormat.of().formatHex(body.getMessageDigest().digest());
+        }
+        if (!actualSha1.equalsIgnoreCase(expectedSha1)) {
+            Files.deleteIfExists(partial);
+            throw new IOException("the downloaded client jar was damaged (checksum mismatch)");
+        }
+        Files.move(partial, destination, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.ATOMIC_MOVE);
+    }
+
+    private static URI findVersionUrl(String version) throws IOException, InterruptedException {
+        for (var entry : fetchJson(VERSION_MANIFEST).getAsJsonArray("versions")) {
+            JsonObject candidate = entry.getAsJsonObject();
+            if (candidate.get("id").getAsString().equals(version)) {
+                return URI.create(candidate.get("url").getAsString());
+            }
+        }
+        throw new IOException("Mojang doesn't list Minecraft " + version);
+    }
+
+    private static JsonObject fetchJson(URI url) throws IOException, InterruptedException {
+        HttpResponse<String> response = HTTP.send(
+                HttpRequest.newBuilder(url).timeout(CONNECT_TIMEOUT).build(),
+                HttpResponse.BodyHandlers.ofString()
+        );
+        requireSuccess(response.statusCode(), url);
+        return JsonParser.parseString(response.body()).getAsJsonObject();
+    }
+
+    private static void requireSuccess(int statusCode, URI url) throws IOException {
+        if (statusCode / 100 != 2) {
+            throw new IOException(url.getHost() + " answered HTTP " + statusCode);
+        }
+    }
+
+    private static MessageDigest sha1() {
+        try {
+            return MessageDigest.getInstance("SHA-1");
+        } catch (NoSuchAlgorithmException error) {
+            throw new IllegalStateException(error);
+        }
+    }
+
+    private static String readableReason(Throwable error) {
+        String message = error.getMessage();
+        return message == null || message.isBlank() ? error.getClass().getSimpleName() : message;
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/NoiseColorScale.java

@@ -0,0 +1,43 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import java.awt.Color;
+
+interface NoiseColorScale {
+    int colorFinite(double value);
+
+    default int colorAt(double value, double worldX, double worldZ) {
+        return colorFinite(value);
+    }
+
+    int colorInvalid();
+
+    default int colorInvalidAt(double worldX, double worldZ) {
+        return colorInvalid();
+    }
+
+    Color displayColorNormalized(double normalized);
+
+    String label();
+
+    double minimum();
+
+    double maximum();
+}

core/src/main/java/com/volmit/iris/core/gui/NoisePalette.java

@@ -0,0 +1,124 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import java.awt.Color;
+
+enum NoisePalette implements NoiseColorScale {
+    TERRAIN("Terrain", 0D, 1D, new int[]{0x071A2F, 0x155E75, 0x2A9D8F, 0xE9C46A, 0xF4F1DE}),
+    SIGNED("Signed", -1D, 1D, new int[]{0x173B66, 0x4F86C6, 0xE7EDF3, 0xE89555, 0x9D3B35}),
+    GRAYSCALE("Grayscale", 0D, 1D, new int[]{0x050505, 0xFFFFFF});
+
+    static final int INVALID_COLOR = 0xFF2DAA;
+
+    private final String label;
+    private final double minimum;
+    private final double maximum;
+    private final int[] lookup;
+    private final Color[] displayColors;
+
+    NoisePalette(String label, double minimum, double maximum, int[] stops) {
+        this.label = label;
+        this.minimum = minimum;
+        this.maximum = maximum;
+        this.lookup = buildLookup(stops);
+        this.displayColors = buildDisplayColors(lookup);
+    }
+
+    int color(double value) {
+        if (!Double.isFinite(value)) {
+            return INVALID_COLOR;
+        }
+        return colorFinite(value);
+    }
+
+    @Override
+    public int colorFinite(double value) {
+        double normalized = (value - minimum) / (maximum - minimum);
+        return colorNormalized(normalized);
+    }
+
+    int colorNormalized(double normalized) {
+        double clipped = Math.max(0D, Math.min(1D, normalized));
+        return lookup[(int) Math.round(clipped * (lookup.length - 1))];
+    }
+
+    @Override
+    public int colorInvalid() {
+        return INVALID_COLOR;
+    }
+
+    @Override
+    public Color displayColorNormalized(double normalized) {
+        double clipped = Math.max(0D, Math.min(1D, normalized));
+        return displayColors[(int) Math.round(clipped * (displayColors.length - 1))];
+    }
+
+    @Override
+    public String label() {
+        return label;
+    }
+
+    @Override
+    public double minimum() {
+        return minimum;
+    }
+
+    @Override
+    public double maximum() {
+        return maximum;
+    }
+
+    @Override
+    public String toString() {
+        return label;
+    }
+
+    private static int[] buildLookup(int[] stops) {
+        int[] values = new int[256];
+        for (int index = 0; index < values.length; index++) {
+            double position = (index / 255D) * (stops.length - 1);
+            int lowerIndex = Math.min(stops.length - 2, (int) position);
+            double fraction = position - lowerIndex;
+            values[index] = interpolate(stops[lowerIndex], stops[lowerIndex + 1], fraction);
+        }
+        return values;
+    }
+
+    private static Color[] buildDisplayColors(int[] lookup) {
+        Color[] colors = new Color[lookup.length];
+        for (int index = 0; index < lookup.length; index++) {
+            colors[index] = new Color(lookup[index]);
+        }
+        return colors;
+    }
+
+    private static int interpolate(int from, int to, double fraction) {
+        int red = channel(from, 16, to, fraction);
+        int green = channel(from, 8, to, fraction);
+        int blue = channel(from, 0, to, fraction);
+        return (red << 16) | (green << 8) | blue;
+    }
+
+    private static int channel(int from, int shift, int to, double fraction) {
+        int fromChannel = (from >>> shift) & 0xFF;
+        int toChannel = (to >>> shift) & 0xFF;
+        return (int) Math.round(fromChannel + ((toChannel - fromChannel) * fraction));
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/NoisePickChart.java

@@ -0,0 +1,340 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.JComponent;
+import java.awt.Color;
+import java.awt.Cursor;
+import java.awt.Dimension;
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Rectangle;
+import java.awt.RenderingHints;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Locale;
+import java.util.Set;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+
+/**
+ * One noise that picks regions or biomes: the spread of its values in view above the bands that pick each option,
+ * and a table of how much of the noise each option is given and how much it gets in view. A long table shows only
+ * the options with the most ground in view until asked for all; a noise with one option to pick is a single line.
+ */
+final class NoisePickChart extends JComponent {
+    private static final long serialVersionUID = 1873365510472853316L;
+    private static final int PREFERRED_WIDTH = 300;
+    private static final int MARGIN = 16;
+    private static final int HISTOGRAM_HEIGHT = 64;
+    private static final int BAND_HEIGHT = 12;
+    private static final int TITLE_GAP = 6;
+    private static final int SECTION_GAP = 12;
+    private static final int BOTTOM_GAP = 14;
+    private static final Color HISTOGRAM_BAR = new Color(0x9D, 0xA0, 0xA8, 150);
+    private static final Color BAND_DIVIDER = new Color(255, 255, 255, 70);
+    private static final String WIDEST_SHARE = "▲ 100.0%";
+    private static final int SHORT_TABLE_ROWS = 6;
+
+    private final NoisePickSpread spread;
+    private final List<NoisePickSpread.Row> rows;
+    private final String optionNoun;
+    private final Consumer<Boolean> onShowAllRowsChanged;
+    private boolean showsAllRows;
+    private Rectangle showAllToggleBounds;
+
+    /**
+     * @param optionNoun           what the noise picks, as a table heading: "Regions" or "Biomes"
+     * @param showsAllRows         whether a long table starts with all its rows
+     * @param onShowAllRowsChanged receives whether the table shows all its rows after the user asked for more or fewer
+     */
+    NoisePickChart(NoisePickSpread spread, String optionNoun, boolean showsAllRows, Consumer<Boolean> onShowAllRowsChanged) {
+        this.spread = spread;
+        this.rows = spread.rows();
+        this.optionNoun = optionNoun;
+        this.showsAllRows = showsAllRows;
+        this.onShowAllRowsChanged = onShowAllRowsChanged;
+        setAlignmentX(LEFT_ALIGNMENT);
+        listenForShowAllToggle();
+    }
+
+    @Override
+    public Dimension getPreferredSize() {
+        if (hasSingleOption()) {
+            return new Dimension(StudioTheme.scale(PREFERRED_WIDTH), StudioTheme.scale(SECTION_GAP) + tableHeight()
+                    + StudioTheme.scale(BOTTOM_GAP));
+        }
+        int height = StudioTheme.scale(SECTION_GAP) + spreadHeight() + StudioTheme.scale(SECTION_GAP) + tableHeight()
+                + StudioTheme.scale(BOTTOM_GAP);
+        return new Dimension(StudioTheme.scale(PREFERRED_WIDTH), height);
+    }
+
+    @Override
+    public Dimension getMaximumSize() {
+        return new Dimension(Integer.MAX_VALUE, getPreferredSize().height);
+    }
+
+    @Override
+    protected void paintComponent(Graphics graphics) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+            canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+            int margin = StudioTheme.scale(MARGIN);
+            int width = getWidth() - margin * 2;
+            int top = StudioTheme.scale(SECTION_GAP);
+            if (hasSingleOption()) {
+                drawSingleOption(canvas, margin, top, width);
+                return;
+            }
+            drawSpread(canvas, margin, top, width);
+            drawTable(canvas, margin, top + spreadHeight() + StudioTheme.scale(SECTION_GAP), width);
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private int spreadHeight() {
+        return sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP) + StudioTheme.scale(HISTOGRAM_HEIGHT)
+                + StudioTheme.scale(2) + StudioTheme.scale(BAND_HEIGHT) + StudioTheme.scale(3) + smallMetrics().getHeight();
+    }
+
+    private boolean hasSingleOption() {
+        return rows.size() == 1;
+    }
+
+    private boolean isLongTable() {
+        return rows.size() > SHORT_TABLE_ROWS;
+    }
+
+    private int tableHeight() {
+        int toggleRows = isLongTable() ? 1 : 0;
+        return sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP) + rowHeight() * (shownRows().size() + toggleRows);
+    }
+
+    // A short table keeps the options with the most ground in view, still in the order the noise meets them.
+    private List<NoisePickSpread.Row> shownRows() {
+        if (showsAllRows || !isLongTable()) {
+            return rows;
+        }
+        Set<NoisePickSpread.Row> largest = rows.stream()
+                .sorted(Comparator.comparingDouble(NoisePickSpread.Row::actualShare).reversed())
+                .limit(SHORT_TABLE_ROWS)
+                .collect(Collectors.toSet());
+        return rows.stream().filter(largest::contains).toList();
+    }
+
+    private void listenForShowAllToggle() {
+        MouseAdapter toggle = new MouseAdapter() {
+            @Override
+            public void mouseClicked(MouseEvent event) {
+                if (showAllToggleBounds == null || !showAllToggleBounds.contains(event.getPoint())) {
+                    return;
+                }
+                showsAllRows = !showsAllRows;
+                onShowAllRowsChanged.accept(showsAllRows);
+                revalidate();
+                repaint();
+            }
+
+            @Override
+            public void mouseMoved(MouseEvent event) {
+                boolean overToggle = showAllToggleBounds != null && showAllToggleBounds.contains(event.getPoint());
+                setCursor(overToggle ? Cursor.getPredefinedCursor(Cursor.HAND_CURSOR) : null);
+            }
+        };
+        addMouseListener(toggle);
+        addMouseMotionListener(toggle);
+    }
+
+    private void drawSingleOption(Graphics2D canvas, int x, int top, int width) {
+        drawSectionTitle(canvas, spread.title(), x, top + sectionMetrics().getAscent());
+        int rowTop = top + sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP);
+        NoisePickSpread.Row row = rows.getFirst();
+        String only = "picked everywhere";
+        int nameRight = x + width - textMetrics().stringWidth(only) - StudioTheme.scale(10);
+        int baseline = drawOptionName(canvas, row, x, rowTop, nameRight);
+        canvas.setColor(StudioTheme.MUTED_TEXT);
+        drawRightAligned(canvas, only, x + width, baseline);
+    }
+
+    private void drawSpread(Graphics2D canvas, int x, int top, int width) {
+        drawSectionTitle(canvas, spread.title(), x, top + sectionMetrics().getAscent());
+        int histogramTop = top + sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP);
+        int histogramHeight = StudioTheme.scale(HISTOGRAM_HEIGHT);
+        drawHistogram(canvas, x, histogramTop, width, histogramHeight);
+        int bandTop = histogramTop + histogramHeight + StudioTheme.scale(2);
+        drawBands(canvas, x, width, histogramTop, bandTop);
+
+        canvas.setFont(StudioTheme.smallFont());
+        canvas.setColor(StudioTheme.SECONDARY_TEXT);
+        FontMetrics metrics = canvas.getFontMetrics();
+        int labelY = bandTop + StudioTheme.scale(BAND_HEIGHT) + StudioTheme.scale(3) + metrics.getAscent();
+        canvas.drawString("0", x, labelY);
+        canvas.drawString("0.5", x + (width - metrics.stringWidth("0.5")) / 2, labelY);
+        canvas.drawString("1", x + width - metrics.stringWidth("1"), labelY);
+    }
+
+    private void drawHistogram(Graphics2D canvas, int x, int top, int width, int height) {
+        long[] histogram = spread.histogram();
+        long peak = 1L;
+        for (long count : histogram) {
+            peak = Math.max(peak, count);
+        }
+        canvas.setColor(HISTOGRAM_BAR);
+        for (int bin = 0; bin < histogram.length; bin++) {
+            int barLeft = x + (bin * width) / histogram.length;
+            int barRight = x + ((bin + 1) * width) / histogram.length;
+            int barHeight = (int) Math.round(height * (histogram[bin] / (double) peak));
+            canvas.fillRect(barLeft, top + height - barHeight, Math.max(1, barRight - barLeft - 1), barHeight);
+        }
+    }
+
+    private void drawBands(Graphics2D canvas, int x, int width, int histogramTop, int bandTop) {
+        int bandHeight = StudioTheme.scale(BAND_HEIGHT);
+        for (NoisePickSpread.Band band : spread.bands()) {
+            int bandLeft = x + (int) Math.round(band.fromNoise() * width);
+            int bandRight = x + (int) Math.round(band.toNoise() * width);
+            canvas.setColor(new Color(band.option().color()));
+            canvas.fillRect(bandLeft, bandTop, Math.max(1, bandRight - bandLeft), bandHeight);
+            if (band.toNoise() < 1D) {
+                canvas.setColor(BAND_DIVIDER);
+                canvas.drawLine(bandRight, histogramTop, bandRight, bandTop + bandHeight - 1);
+            }
+        }
+    }
+
+    private void drawTable(Graphics2D canvas, int x, int top, int width) {
+        int columnGap = StudioTheme.scale(10);
+        int actualRight = x + width;
+        int weightRight = actualRight - textMetrics().stringWidth(WIDEST_SHARE) - columnGap;
+        int nameRight = weightRight - textMetrics().stringWidth(WIDEST_SHARE) - columnGap;
+        int titleBaseline = top + sectionMetrics().getAscent();
+        drawSectionTitle(canvas, optionNoun, x, titleBaseline);
+        canvas.setFont(StudioTheme.sectionFont());
+        drawRightAligned(canvas, "WEIGHT", weightRight, titleBaseline);
+        drawRightAligned(canvas, "IN VIEW", actualRight, titleBaseline);
+
+        int rowHeight = rowHeight();
+        int rowTop = top + sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP);
+        for (NoisePickSpread.Row row : shownRows()) {
+            int baseline = drawOptionName(canvas, row, x, rowTop, nameRight);
+            canvas.setColor(StudioTheme.SECONDARY_TEXT);
+            drawRightAligned(canvas, percent(row.weightShare()), weightRight, baseline);
+            boolean farFromWeight = row.isFarBelowWeight() || row.isFarAboveWeight();
+            canvas.setColor(farFromWeight ? StudioTheme.WARNING : StudioTheme.TEXT);
+            drawRightAligned(canvas, actualText(row), actualRight, baseline);
+            rowTop += rowHeight;
+        }
+        showAllToggleBounds = isLongTable() ? drawShowAllToggle(canvas, x, rowTop) : null;
+    }
+
+    // Returns the row's text baseline.
+    private int drawOptionName(Graphics2D canvas, NoisePickSpread.Row row, int x, int rowTop, int nameRight) {
+        FontMetrics text = textMetrics();
+        int rowHeight = rowHeight();
+        int swatchSize = text.getAscent() - text.getDescent();
+        int baseline = rowTop + (rowHeight + text.getAscent() - text.getDescent()) / 2;
+        int arc = StudioTheme.scale(3);
+        canvas.setColor(new Color(row.option().color()));
+        canvas.fillRoundRect(x, rowTop + (rowHeight - swatchSize) / 2, swatchSize, swatchSize, arc, arc);
+        canvas.setFont(StudioTheme.font());
+        canvas.setColor(StudioTheme.TEXT);
+        int nameLeft = x + swatchSize + StudioTheme.scale(7);
+        canvas.drawString(fit(canvas, distinctName(row, rows), nameRight - nameLeft), nameLeft, baseline);
+        return baseline;
+    }
+
+    private Rectangle drawShowAllToggle(Graphics2D canvas, int x, int rowTop) {
+        String text = showsAllRows
+                ? "Show fewer"
+                : "Show all " + rows.size() + " " + optionNoun.toLowerCase(Locale.ROOT);
+        FontMetrics metrics = textMetrics();
+        int baseline = rowTop + (rowHeight() + metrics.getAscent() - metrics.getDescent()) / 2;
+        canvas.setFont(StudioTheme.font());
+        canvas.setColor(StudioTheme.LINK);
+        canvas.drawString(text, x, baseline);
+        return new Rectangle(x, rowTop, metrics.stringWidth(text), rowHeight());
+    }
+
+    private int rowHeight() {
+        return textMetrics().getHeight() + StudioTheme.scale(4);
+    }
+
+    private FontMetrics textMetrics() {
+        return getFontMetrics(StudioTheme.font());
+    }
+
+    private FontMetrics smallMetrics() {
+        return getFontMetrics(StudioTheme.smallFont());
+    }
+
+    private FontMetrics sectionMetrics() {
+        return getFontMetrics(StudioTheme.sectionFont());
+    }
+
+    private static void drawSectionTitle(Graphics2D canvas, String title, int x, int y) {
+        canvas.setFont(StudioTheme.sectionFont());
+        canvas.setColor(StudioTheme.MUTED_TEXT);
+        canvas.drawString(title.toUpperCase(Locale.ROOT), x, y);
+    }
+
+    private static void drawRightAligned(Graphics2D canvas, String text, int right, int y) {
+        canvas.drawString(text, right - canvas.getFontMetrics().stringWidth(text), y);
+    }
+
+    // Two biomes in different folders can share a name, so their keys tell them apart.
+    private static String distinctName(NoisePickSpread.Row row, List<NoisePickSpread.Row> rows) {
+        String name = row.option().name();
+        boolean shared = rows.stream().anyMatch(other -> other != row && other.option().name().equals(name));
+        return shared ? name + " (" + row.option().key() + ")" : name;
+    }
+
+    private static String actualText(NoisePickSpread.Row row) {
+        if (row.isFarBelowWeight()) {
+            return "▼ " + percent(row.actualShare());
+        }
+        if (row.isFarAboveWeight()) {
+            return "▲ " + percent(row.actualShare());
+        }
+        return percent(row.actualShare());
+    }
+
+    static String percent(double share) {
+        if (share > 0D && share < 0.001D) {
+            return "<0.1%";
+        }
+        return String.format(Locale.ROOT, "%.1f%%", share * 100D);
+    }
+
+    private static String fit(Graphics2D canvas, String text, int maxWidth) {
+        FontMetrics metrics = canvas.getFontMetrics();
+        if (metrics.stringWidth(text) <= maxWidth) {
+            return text;
+        }
+        String shortened = text;
+        while (shortened.length() > 1 && metrics.stringWidth(shortened + "…") > maxWidth) {
+            shortened = shortened.substring(0, shortened.length() - 1);
+        }
+        return shortened + "…";
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/NoisePickSpread.java

@@ -0,0 +1,198 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * How a noise picks one of several regions or biomes, measured against the noise values in view: rarity splits the
+ * noise from 0 to 1 into one band per option, and each spot gets the option whose band its noise value falls in.
+ */
+final class NoisePickSpread {
+    static final int HISTOGRAM_BINS = 50;
+
+    private final String title;
+    private final List<Band> bands;
+    private final long[] histogram = new long[HISTOGRAM_BINS];
+    private final long[] samplesByBand;
+    private long sampleCount;
+    private long belowZeroCount;
+    private long aboveOneCount;
+
+    private NoisePickSpread(String title, List<Band> bands) {
+        this.title = title;
+        this.bands = List.copyOf(bands);
+        this.samplesByBand = new long[bands.size()];
+    }
+
+    /**
+     * @param legacyRarity whether the dimension splits the noise the legacy way
+     */
+    static NoisePickSpread of(String title, List<Option> options, boolean legacyRarity) {
+        return new NoisePickSpread(title, splitNoise(options, legacyRarity));
+    }
+
+    /**
+     * The band of noise each option gets, in the order the noise meets them.
+     */
+    static List<Band> splitNoise(List<Option> options, boolean legacyRarity) {
+        return legacyRarity ? legacyBands(options) : bands(options);
+    }
+
+    void add(double noise) {
+        if (bands.isEmpty() || !Double.isFinite(noise)) {
+            return;
+        }
+        sampleCount++;
+        if (noise < 0D) {
+            belowZeroCount++;
+        } else if (noise > 1D) {
+            aboveOneCount++;
+        }
+        histogram[Math.clamp((int) (noise * HISTOGRAM_BINS), 0, HISTOGRAM_BINS - 1)]++;
+        samplesByBand[bandIndexOf(noise)]++;
+    }
+
+    String title() {
+        return title;
+    }
+
+    List<Band> bands() {
+        return bands;
+    }
+
+    long[] histogram() {
+        return histogram;
+    }
+
+    long sampleCount() {
+        return sampleCount;
+    }
+
+    double belowZeroShare() {
+        return share(belowZeroCount);
+    }
+
+    double aboveOneShare() {
+        return share(aboveOneCount);
+    }
+
+    /**
+     * Every option once, with its bands' widths and samples added up, in the order the noise meets them.
+     */
+    List<Row> rows() {
+        Map<String, Row> rows = new LinkedHashMap<>();
+        for (int index = 0; index < bands.size(); index++) {
+            Band band = bands.get(index);
+            Row row = new Row(band.option(), band.width(), share(samplesByBand[index]));
+            rows.merge(band.option().key(), row, Row::plus);
+        }
+        return new ArrayList<>(rows.values());
+    }
+
+    private double share(long count) {
+        return sampleCount == 0 ? 0D : count / (double) sampleCount;
+    }
+
+    // The engine gives values below 0 the first option and values above 1 the last, the same as these bands.
+    private int bandIndexOf(double noise) {
+        for (int index = 0; index < bands.size(); index++) {
+            if (noise <= bands.get(index).toNoise()) {
+                return index;
+            }
+        }
+        return bands.size() - 1;
+    }
+
+    // Mirrors IRare.pick: each option gets a share of the noise in proportion to one over its rarity.
+    private static List<Band> bands(List<Option> options) {
+        double total = 0D;
+        for (Option option : options) {
+            total += 1D / option.rarity();
+        }
+        List<Band> bands = new ArrayList<>();
+        double from = 0D;
+        for (Option option : options) {
+            double to = options.size() == 1 ? 1D : from + (1D / option.rarity()) / total;
+            bands.add(new Band(option, from, to));
+            from = to;
+        }
+        return bands;
+    }
+
+    // Mirrors IRare.pickLegacy: each option gets a share in proportion to the total rarity minus its own.
+    private static List<Band> legacyBands(List<Option> options) {
+        if (options.size() <= 1) {
+            return bands(options);
+        }
+        double totalRarity = 0D;
+        for (Option option : options) {
+            totalRarity += option.rarity();
+        }
+        double whole = totalRarity * (options.size() - 1);
+        List<Band> bands = new ArrayList<>();
+        double from = 0D;
+        double buffer = 0D;
+        for (Option option : options) {
+            buffer += totalRarity - option.rarity();
+            double to = buffer / whole;
+            bands.add(new Band(option, from, to));
+            from = to;
+        }
+        return bands;
+    }
+
+    /**
+     * A region or biome the noise can pick.
+     */
+    record Option(String key, String name, int color, int rarity) {
+    }
+
+    /**
+     * The noise values from {@code fromNoise} to {@code toNoise} that pick the option.
+     */
+    record Band(Option option, double fromNoise, double toNoise) {
+        double width() {
+            return toNoise - fromNoise;
+        }
+    }
+
+    /**
+     * @param weightShare how much of the noise from 0 to 1 picks the option
+     * @param actualShare how much of the noise in view picks the option
+     */
+    record Row(Option option, double weightShare, double actualShare) {
+        private static final double FAR_FROM_WEIGHT_FACTOR = 2D;
+
+        Row plus(Row other) {
+            return new Row(option, weightShare + other.weightShare, actualShare + other.actualShare);
+        }
+
+        boolean isFarBelowWeight() {
+            return actualShare * FAR_FROM_WEIGHT_FACTOR < weightShare;
+        }
+
+        boolean isFarAboveWeight() {
+            return actualShare > weightShare * FAR_FROM_WEIGHT_FACTOR;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/NoiseRenderCoordinator.java

@@ -0,0 +1,378 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.util.function.NoiseProvider;
+
+import java.awt.image.BufferedImage;
+import java.util.Objects;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.RejectedExecutionException;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
+
+final class NoiseRenderCoordinator implements AutoCloseable {
+    private static final int BANDS_PER_WORKER = 4;
+
+    private final int workerCount;
+    private final Listener listener;
+    private final ThreadPoolExecutor workers;
+    private final AtomicReference<RenderGeneration> latestRequested = new AtomicReference<>();
+    private final AtomicLong latestRevision = new AtomicLong();
+    private final AtomicBoolean closed = new AtomicBoolean();
+
+    NoiseRenderCoordinator(Listener listener) {
+        this(Math.min(4, Math.max(1, Runtime.getRuntime().availableProcessors() / 2)), listener);
+    }
+
+    NoiseRenderCoordinator(int workerCount, Listener listener) {
+        this.workerCount = Math.max(1, workerCount);
+        this.listener = Objects.requireNonNull(listener, "listener");
+        AtomicInteger threadIds = new AtomicInteger();
+        ThreadFactory workerThreadFactory = runnable -> {
+            Thread thread = new Thread(runnable, "Iris Noise Renderer " + threadIds.incrementAndGet());
+            thread.setDaemon(true);
+            thread.setPriority(Thread.MIN_PRIORITY);
+            return thread;
+        };
+        workers = new ThreadPoolExecutor(this.workerCount, this.workerCount, 30L, TimeUnit.SECONDS,
+                new LinkedBlockingQueue<>(), workerThreadFactory);
+        workers.allowCoreThreadTimeOut(true);
+        GuiHost.interruptOnPluginShutdown(workers);
+    }
+
+    void request(Request request) {
+        Objects.requireNonNull(request, "request");
+        if (closed.get()) {
+            return;
+        }
+        latestRevision.accumulateAndGet(request.revision(), Math::max);
+        RenderGeneration generation = new RenderGeneration(request, Math.min(workerCount * BANDS_PER_WORKER, outputHeight(request)));
+        latestRequested.set(generation);
+        listener.onRenderStarted(request);
+        for (int band = 0; band < generation.bandCount(); band++) {
+            int bandIndex = band;
+            try {
+                workers.execute(() -> renderBand(generation, bandIndex));
+            } catch (RejectedExecutionException rejected) {
+                generation.fail(rejected);
+                finishBand(generation);
+            }
+        }
+    }
+
+    void cancel(long revision) {
+        latestRevision.accumulateAndGet(revision, Math::max);
+        latestRequested.set(null);
+    }
+
+    boolean isClosed() {
+        return closed.get();
+    }
+
+    static int sampleStepForBudget(int width, int height, long sampleBudget) {
+        if (width < 1 || height < 1 || sampleBudget < 1L) {
+            throw new IllegalArgumentException("Invalid noise sample budget");
+        }
+        long totalSamples = (long) width * height;
+        int sampleStep = Math.max(1, (int) Math.ceil(Math.sqrt(totalSamples / (double) sampleBudget)));
+        while (sampleCount(width, height, sampleStep) > sampleBudget) {
+            sampleStep++;
+        }
+        return sampleStep;
+    }
+
+    static long sampleCount(int width, int height, int sampleStep) {
+        if (width < 1 || height < 1 || sampleStep < 1) {
+            throw new IllegalArgumentException("Invalid noise sample dimensions");
+        }
+        long outputWidth = ((long) width + sampleStep - 1L) / sampleStep;
+        long outputHeight = ((long) height + sampleStep - 1L) / sampleStep;
+        return outputWidth * outputHeight;
+    }
+
+    static int nextRefinementStep(int width, int height, int currentStep, long sampleBudget) {
+        if (currentStep <= 1) {
+            throw new IllegalArgumentException("Noise refinement requires a coarse input");
+        }
+        return Math.min(currentStep, sampleStepForBudget(width, height, sampleBudget));
+    }
+
+    static long timeBoundSampleBudget(long completedSamples, double milliseconds, double targetMilliseconds,
+                                      long minimumBudget, long maximumBudget) {
+        if (completedSamples < 1L
+                || !Double.isFinite(milliseconds)
+                || milliseconds <= 0D
+                || !Double.isFinite(targetMilliseconds)
+                || targetMilliseconds <= 0D
+                || minimumBudget < 1L
+                || maximumBudget < minimumBudget) {
+            throw new IllegalArgumentException("Invalid timed noise sample budget");
+        }
+        double projectedSamples = Math.ceil((completedSamples / milliseconds) * targetMilliseconds);
+        long timeBoundBudget = (long) Math.min(maximumBudget, projectedSamples);
+        return Math.max(minimumBudget, timeBoundBudget);
+    }
+
+    @Override
+    public void close() {
+        if (!closed.compareAndSet(false, true)) {
+            return;
+        }
+        latestRevision.incrementAndGet();
+        latestRequested.set(null);
+        workers.shutdownNow();
+    }
+
+    // Bands of a frame that was replaced are skipped, so a new frame only waits for the rows already being drawn.
+    private void renderBand(RenderGeneration generation, int bandIndex) {
+        try {
+            if (isCurrent(generation)) {
+                renderRows(generation, bandIndex);
+            }
+        } catch (Throwable error) {
+            generation.fail(error);
+        } finally {
+            finishBand(generation);
+        }
+    }
+
+    private void finishBand(RenderGeneration generation) {
+        if (!generation.completeBand() || !isCurrent(generation)) {
+            return;
+        }
+        Throwable failure = generation.failure();
+        if (failure != null) {
+            listener.onRenderFailed(generation.request(), failure);
+            return;
+        }
+        listener.onRenderCompleted(generation.result());
+    }
+
+    private void renderRows(RenderGeneration generation, int bandIndex) {
+        Request request = generation.request();
+        int outputWidth = generation.outputWidth();
+        int outputHeight = generation.outputHeight();
+        int[] pixels = generation.pixels();
+        BandStats stats = generation.bandStats(bandIndex);
+        int fromY = (outputHeight * bandIndex) / generation.bandCount();
+        int toY = (outputHeight * (bandIndex + 1)) / generation.bandCount();
+        double sampleOffset = request.sampleStep() * 0.5D;
+        double startWorldX = request.viewport().worldX(sampleOffset, request.width());
+        double worldStep = request.viewport().blocksPerPixel() * request.sampleStep();
+        NoiseColorScale colorScale = request.colorScale();
+        double paletteMinimum = colorScale.minimum();
+        double paletteMaximum = colorScale.maximum();
+        for (int y = fromY; y < toY; y++) {
+            double screenY = (y * (double) request.sampleStep()) + sampleOffset;
+            double worldZ = request.viewport().worldZ(screenY, request.height());
+            double worldX = startWorldX;
+            int pixelIndex = y * outputWidth;
+            boolean centerRow = y == outputHeight / 2;
+            for (int x = 0; x < outputWidth; x++) {
+                if ((x & 31) == 0 && (!isCurrent(generation) || Thread.currentThread().isInterrupted())) {
+                    return;
+                }
+                double value = request.sampler().noise(worldX, worldZ);
+                boolean center = centerRow && x == outputWidth / 2;
+                if (Double.isFinite(value)) {
+                    pixels[pixelIndex++] = colorScale.colorAt(value, worldX, worldZ);
+                    stats.acceptFinite(value, center, paletteMinimum, paletteMaximum);
+                } else {
+                    pixels[pixelIndex++] = colorScale.colorInvalidAt(worldX, worldZ);
+                    stats.acceptInvalid(value, center);
+                }
+                worldX += worldStep;
+            }
+        }
+    }
+
+    private boolean isCurrent(RenderGeneration generation) {
+        return !closed.get()
+                && latestRequested.get() == generation
+                && generation.request().revision() >= latestRevision.get();
+    }
+
+    private static int outputWidth(Request request) {
+        return Math.max(1, (request.width() + request.sampleStep() - 1) / request.sampleStep());
+    }
+
+    private static int outputHeight(Request request) {
+        return Math.max(1, (request.height() + request.sampleStep() - 1) / request.sampleStep());
+    }
+
+    private static RenderStats combine(BandStats[] bands) {
+        long samples = 0L;
+        long underflow = 0L;
+        long overflow = 0L;
+        long invalid = 0L;
+        double minimum = Double.POSITIVE_INFINITY;
+        double maximum = Double.NEGATIVE_INFINITY;
+        double centerValue = Double.NaN;
+        for (BandStats band : bands) {
+            samples += band.samples;
+            underflow += band.underflow;
+            overflow += band.overflow;
+            invalid += band.invalid;
+            minimum = Math.min(minimum, band.minimum);
+            maximum = Math.max(maximum, band.maximum);
+            if (!Double.isNaN(band.centerValue)) {
+                centerValue = band.centerValue;
+            }
+        }
+        if (minimum == Double.POSITIVE_INFINITY) {
+            minimum = Double.NaN;
+            maximum = Double.NaN;
+        }
+        return new RenderStats(samples, minimum, maximum, centerValue, underflow, overflow, invalid);
+    }
+
+    interface Listener {
+        void onRenderStarted(Request request);
+
+        void onRenderCompleted(Result result);
+
+        void onRenderFailed(Request request, Throwable error);
+    }
+
+    record Request(long revision, NoiseProvider sampler, NoiseViewport viewport, NoiseColorScale colorScale,
+                   int width, int height, int sampleStep) {
+        Request {
+            Objects.requireNonNull(sampler, "sampler");
+            Objects.requireNonNull(viewport, "viewport");
+            Objects.requireNonNull(colorScale, "colorScale");
+            if (revision < 0L || width < 1 || height < 1 || sampleStep < 1) {
+                throw new IllegalArgumentException("Invalid noise render request");
+            }
+        }
+    }
+
+    record Result(Request request, BufferedImage image, double milliseconds, long samples, double minimum,
+                  double maximum, double centerValue, long underflow, long overflow, long invalid) {
+    }
+
+    private static final class RenderGeneration {
+        private final Request request;
+        private final long startedNanos = System.nanoTime();
+        private final int outputWidth;
+        private final int outputHeight;
+        private final int[] pixels;
+        private final BandStats[] bandStats;
+        private final AtomicInteger remainingBands;
+        private final AtomicReference<Throwable> failure = new AtomicReference<>();
+
+        private RenderGeneration(Request request, int bandCount) {
+            this.request = request;
+            this.outputWidth = NoiseRenderCoordinator.outputWidth(request);
+            this.outputHeight = NoiseRenderCoordinator.outputHeight(request);
+            this.pixels = new int[outputWidth * outputHeight];
+            this.bandStats = new BandStats[Math.max(1, bandCount)];
+            for (int band = 0; band < bandStats.length; band++) {
+                bandStats[band] = new BandStats();
+            }
+            this.remainingBands = new AtomicInteger(bandStats.length);
+        }
+
+        private Request request() {
+            return request;
+        }
+
+        private int bandCount() {
+            return bandStats.length;
+        }
+
+        private int outputWidth() {
+            return outputWidth;
+        }
+
+        private int outputHeight() {
+            return outputHeight;
+        }
+
+        private int[] pixels() {
+            return pixels;
+        }
+
+        private BandStats bandStats(int band) {
+            return bandStats[band];
+        }
+
+        private void fail(Throwable error) {
+            failure.compareAndSet(null, error);
+        }
+
+        private Throwable failure() {
+            return failure.get();
+        }
+
+        // True for the band that finishes last, which is the one that publishes the frame.
+        private boolean completeBand() {
+            return remainingBands.decrementAndGet() == 0;
+        }
+
+        private Result result() {
+            BufferedImage image = GuiHost.uncachedImage(pixels, outputWidth, outputHeight);
+            RenderStats combined = combine(bandStats);
+            double milliseconds = (System.nanoTime() - startedNanos) / 1_000_000D;
+            return new Result(request, image, milliseconds, combined.samples, combined.minimum, combined.maximum,
+                    combined.centerValue, combined.underflow, combined.overflow, combined.invalid);
+        }
+    }
+
+    private static final class BandStats {
+        private long samples;
+        private long underflow;
+        private long overflow;
+        private long invalid;
+        private double minimum = Double.POSITIVE_INFINITY;
+        private double maximum = Double.NEGATIVE_INFINITY;
+        private double centerValue = Double.NaN;
+
+        private void acceptFinite(double value, boolean center, double paletteMinimum, double paletteMaximum) {
+            samples++;
+            if (center) {
+                centerValue = value;
+            }
+            minimum = Math.min(minimum, value);
+            maximum = Math.max(maximum, value);
+            if (value < paletteMinimum) {
+                underflow++;
+            } else if (value > paletteMaximum) {
+                overflow++;
+            }
+        }
+
+        private void acceptInvalid(double value, boolean center) {
+            samples++;
+            invalid++;
+            if (center) {
+                centerValue = value;
+            }
+        }
+    }
+
+    private record RenderStats(long samples, double minimum, double maximum, double centerValue,
+                               long underflow, long overflow, long invalid) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/NoiseViewport.java

@@ -0,0 +1,70 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+record NoiseViewport(double centerX, double centerZ, double blocksPerPixel) {
+    static final double MIN_BLOCKS_PER_PIXEL = 0.0001D;
+    static final double MAX_BLOCKS_PER_PIXEL = 1_000_000D;
+
+    NoiseViewport {
+        if (!Double.isFinite(centerX) || !Double.isFinite(centerZ)) {
+            throw new IllegalArgumentException("Viewport center must be finite");
+        }
+        if (!Double.isFinite(blocksPerPixel) || blocksPerPixel <= 0D) {
+            throw new IllegalArgumentException("Viewport scale must be finite and positive");
+        }
+    }
+
+    double worldX(double screenX, int width) {
+        return centerX + ((screenX - (width / 2D)) * blocksPerPixel);
+    }
+
+    double worldZ(double screenZ, int height) {
+        return centerZ + ((screenZ - (height / 2D)) * blocksPerPixel);
+    }
+
+    double screenX(double worldX, int width) {
+        return ((worldX - centerX) / blocksPerPixel) + (width / 2D);
+    }
+
+    double screenZ(double worldZ, int height) {
+        return ((worldZ - centerZ) / blocksPerPixel) + (height / 2D);
+    }
+
+    NoiseViewport panPixels(double deltaX, double deltaZ) {
+        return new NoiseViewport(
+                centerX - (deltaX * blocksPerPixel),
+                centerZ - (deltaZ * blocksPerPixel),
+                blocksPerPixel
+        );
+    }
+
+    NoiseViewport zoomAt(double screenX, double screenZ, int width, int height, double factor) {
+        if (!Double.isFinite(factor) || factor <= 0D) {
+            throw new IllegalArgumentException("Zoom factor must be finite and positive");
+        }
+        double anchorX = worldX(screenX, width);
+        double anchorZ = worldZ(screenZ, height);
+        double nextScale = Math.max(MIN_BLOCKS_PER_PIXEL,
+                Math.min(MAX_BLOCKS_PER_PIXEL, blocksPerPixel * factor));
+        double nextCenterX = anchorX - ((screenX - (width / 2D)) * nextScale);
+        double nextCenterZ = anchorZ - ((screenZ - (height / 2D)) * nextScale);
+        return new NoiseViewport(nextCenterX, nextCenterZ, nextScale);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectBrowser.java

@@ -0,0 +1,276 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+import javax.swing.JTree;
+import javax.swing.ToolTipManager;
+import javax.swing.event.DocumentEvent;
+import javax.swing.event.DocumentListener;
+import javax.swing.tree.DefaultMutableTreeNode;
+import javax.swing.tree.DefaultTreeCellRenderer;
+import javax.swing.tree.DefaultTreeModel;
+import javax.swing.tree.TreePath;
+import javax.swing.tree.TreeSelectionModel;
+import java.awt.BorderLayout;
+import java.awt.Component;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.function.Consumer;
+
+/**
+ * Every object in the pack as a folder tree, with a search that matches every word typed anywhere in an object's path.
+ */
+final class ObjectBrowser extends JPanel {
+    private static final long serialVersionUID = 6795434561028735214L;
+    private static final int ROW_HEIGHT = 24;
+
+    private final Consumer<String> onObjectChosen;
+    private final JTextField searchField = new JTextField();
+    private final DefaultTreeModel treeModel = new DefaultTreeModel(new DefaultMutableTreeNode());
+    private final JTree tree = new JTree(treeModel);
+    private final JLabel countLabel = new JLabel();
+    private final String noun;
+    private List<String> objectKeys = List.of();
+    private String chosenKey;
+    private boolean updatingSelection;
+
+    /**
+     * @param noun what one entry is called in the browser's texts, such as "object"
+     */
+    ObjectBrowser(String noun, Consumer<String> onObjectChosen) {
+        super(new BorderLayout());
+        this.noun = noun;
+        this.onObjectChosen = onObjectChosen;
+        countLabel.setText("Loading " + noun + "s...");
+        StudioToolbar.makeSearchField(searchField, "Search " + noun + "s...");
+        searchField.getDocument().addDocumentListener(new DocumentListener() {
+            @Override
+            public void insertUpdate(DocumentEvent event) {
+                rebuildTree();
+            }
+
+            @Override
+            public void removeUpdate(DocumentEvent event) {
+                rebuildTree();
+            }
+
+            @Override
+            public void changedUpdate(DocumentEvent event) {
+                rebuildTree();
+            }
+        });
+        tree.setRootVisible(false);
+        tree.setShowsRootHandles(true);
+        tree.setRowHeight(StudioTheme.scale(ROW_HEIGHT));
+        tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
+        tree.setCellRenderer(new EntryRenderer());
+        ToolTipManager.sharedInstance().registerComponent(tree);
+        tree.addTreeSelectionListener(event -> {
+            if (!updatingSelection && nodeAt(event.getPath()) instanceof Entry entry && entry.isObject()) {
+                chosenKey = entry.key();
+                onObjectChosen.accept(entry.key());
+            }
+        });
+        countLabel.setFont(StudioTheme.smallFont());
+        countLabel.setForeground(StudioTheme.SECONDARY_TEXT);
+        add(StudioToolbar.padded(searchField, 8, 8, 8, 8), BorderLayout.NORTH);
+        add(StickyFolderHeaders.around(tree, StudioToolbar.scroll(tree)), BorderLayout.CENTER);
+        add(StudioToolbar.padded(countLabel, 6, 12, 8, 12), BorderLayout.SOUTH);
+    }
+
+    void showObjects(List<String> keys) {
+        objectKeys = keys.stream().sorted(Comparator.comparing(key -> key.toLowerCase(Locale.ROOT))).toList();
+        countLabel.setText(objectKeys.size() == 1 ? "1 " + noun : objectKeys.size() + " " + noun + "s");
+        rebuildTree();
+    }
+
+    void showError(String text) {
+        countLabel.setText(text);
+    }
+
+    String firstObject() {
+        return objectKeys.isEmpty() ? null : objectKeys.get(0);
+    }
+
+    private void rebuildTree() {
+        String[] words = searchField.getText().trim().toLowerCase(Locale.ROOT).split("\\s+");
+        boolean searching = !searchField.getText().isBlank();
+        DefaultMutableTreeNode root = searching ? searchResults(words) : folderTree();
+        treeModel.setRoot(root);
+        if (searching) {
+            expandAll();
+        }
+        selectChosen();
+    }
+
+    private DefaultMutableTreeNode searchResults(String[] words) {
+        DefaultMutableTreeNode root = new DefaultMutableTreeNode();
+        for (String key : objectKeys) {
+            if (matchesEveryWord(key, words)) {
+                root.add(new DefaultMutableTreeNode(Entry.object(key, key)));
+            }
+        }
+        if (root.getChildCount() == 0) {
+            root.add(new DefaultMutableTreeNode(Entry.note("No matching " + noun + "s")));
+        }
+        return root;
+    }
+
+    private static boolean matchesEveryWord(String key, String[] words) {
+        String lowerKey = key.toLowerCase(Locale.ROOT);
+        for (String word : words) {
+            if (!lowerKey.contains(word)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    // Folders come before the objects beside them, like a file browser.
+    private DefaultMutableTreeNode folderTree() {
+        Folder top = new Folder();
+        for (String key : objectKeys) {
+            Folder folder = top;
+            String[] parts = key.split("/");
+            for (int index = 0; index < parts.length - 1; index++) {
+                folder = folder.subfolders.computeIfAbsent(parts[index], name -> new Folder());
+            }
+            folder.objects.add(key);
+        }
+        DefaultMutableTreeNode root = new DefaultMutableTreeNode();
+        addFolderContents(root, top, "");
+        return root;
+    }
+
+    private static void addFolderContents(DefaultMutableTreeNode node, Folder folder, String path) {
+        for (Map.Entry<String, Folder> subfolder : folder.subfolders.entrySet()) {
+            String subfolderPath = path + subfolder.getKey() + "/";
+            DefaultMutableTreeNode child = new DefaultMutableTreeNode(Entry.folder(subfolder.getKey(), subfolderPath));
+            addFolderContents(child, subfolder.getValue(), subfolderPath);
+            node.add(child);
+        }
+        for (String key : folder.objects) {
+            node.add(new DefaultMutableTreeNode(Entry.object(key.substring(key.lastIndexOf('/') + 1), key)));
+        }
+    }
+
+    void select(String key) {
+        chosenKey = key;
+        selectChosen();
+    }
+
+    private void selectChosen() {
+        DefaultMutableTreeNode node = chosenKey == null ? null : findObjectNode((DefaultMutableTreeNode) treeModel.getRoot());
+        updatingSelection = true;
+        try {
+            if (node == null) {
+                tree.clearSelection();
+                return;
+            }
+            TreePath path = new TreePath(node.getPath());
+            tree.setSelectionPath(path);
+            tree.scrollPathToVisible(path);
+        } finally {
+            updatingSelection = false;
+        }
+    }
+
+    private DefaultMutableTreeNode findObjectNode(DefaultMutableTreeNode node) {
+        if (node.getUserObject() instanceof Entry entry && entry.isObject() && entry.key().equals(chosenKey)) {
+            return node;
+        }
+        for (int index = 0; index < node.getChildCount(); index++) {
+            DefaultMutableTreeNode found = findObjectNode((DefaultMutableTreeNode) node.getChildAt(index));
+            if (found != null) {
+                return found;
+            }
+        }
+        return null;
+    }
+
+    private void expandAll() {
+        for (int row = 0; row < tree.getRowCount(); row++) {
+            tree.expandRow(row);
+        }
+    }
+
+    private static Object nodeAt(TreePath path) {
+        return path == null ? null : ((DefaultMutableTreeNode) path.getLastPathComponent()).getUserObject();
+    }
+
+    private static final class Folder {
+        private final Map<String, Folder> subfolders = new LinkedHashMap<>();
+        private final List<String> objects = new ArrayList<>();
+    }
+
+    /**
+     * A row of the tree: an object with its key, a folder with its path, or a note without either.
+     */
+    private record Entry(String label, String key, String folderPath) {
+        static Entry object(String label, String key) {
+            return new Entry(label, key, null);
+        }
+
+        static Entry folder(String label, String path) {
+            return new Entry(label, null, path);
+        }
+
+        static Entry note(String text) {
+            return new Entry(text, null, null);
+        }
+
+        boolean isObject() {
+            return key != null;
+        }
+
+        @Override
+        public String toString() {
+            return label;
+        }
+    }
+
+    private static final class EntryRenderer extends DefaultTreeCellRenderer {
+        private static final long serialVersionUID = -4316652201793418740L;
+
+        private EntryRenderer() {
+            setLeafIcon(null);
+            setOpenIcon(null);
+            setClosedIcon(null);
+        }
+
+        @Override
+        public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded,
+                                                      boolean leaf, int row, boolean focus) {
+            Object userObject = ((DefaultMutableTreeNode) value).getUserObject();
+            super.getTreeCellRendererComponent(tree, userObject == null ? "" : userObject.toString(), selected, expanded, leaf, row, false);
+            boolean isNote = userObject instanceof Entry entry && !entry.isObject() && entry.folderPath() == null;
+            setFont(StudioTheme.font());
+            setForeground(isNote ? StudioTheme.MUTED_TEXT : StudioTheme.TEXT);
+            setToolTipText(userObject instanceof Entry entry ? entry.isObject() ? entry.key() : entry.folderPath() : null);
+            return this;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectCamera.java

@@ -0,0 +1,44 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+/**
+ * Where the object viewer looks from: turned by yaw around the vertical axis, tilted down by pitch, both in radians.
+ * Zoom 1 fits the object in the view at the starting angle. Pan moves the picture in fractions of the view's size.
+ */
+record ObjectCamera(double yaw, double pitch, double zoom, double panX, double panY) {
+    static final ObjectCamera START = new ObjectCamera(0.76D, 0.38D, 1.72D, 0D, 0.025D);
+    private static final double RADIANS_PER_DRAGGED_PIXEL = 0.008D;
+    private static final double MAXIMUM_PITCH = 1.3D;
+    private static final double MINIMUM_ZOOM = 0.4D;
+    private static final double MAXIMUM_ZOOM = 12D;
+
+    ObjectCamera orbitedBy(double draggedX, double draggedY) {
+        double nextPitch = Math.max(-MAXIMUM_PITCH, Math.min(MAXIMUM_PITCH, pitch + draggedY * RADIANS_PER_DRAGGED_PIXEL));
+        return new ObjectCamera(yaw + draggedX * RADIANS_PER_DRAGGED_PIXEL, nextPitch, zoom, panX, panY);
+    }
+
+    ObjectCamera zoomedBy(double factor) {
+        return new ObjectCamera(yaw, pitch, Math.max(MINIMUM_ZOOM, Math.min(MAXIMUM_ZOOM, zoom * factor)), panX, panY);
+    }
+
+    ObjectCamera pannedBy(double fractionX, double fractionY) {
+        return new ObjectCamera(yaw, pitch, zoom, panX + fractionX, panY + fractionY);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectExplorer.java

@@ -0,0 +1,548 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.BlockTextures.BlockTexture;
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisObject;
+import org.bukkit.NamespacedKey;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.util.BlockVector;
+
+import javax.swing.JComponent;
+import javax.swing.JPanel;
+import java.awt.CardLayout;
+import java.awt.EventQueue;
+import java.awt.event.KeyEvent;
+import java.awt.image.BufferedImage;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.OptionalLong;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicLong;
+
+/**
+ * The map window's Objects and Procedural views: everything its source offers in a folder tree, the chosen one in 3D,
+ * and what it is made of. A procedural object's variants can also be compared side by side, baked from any seed.
+ * Inspired by the Procedural Objects workbench.
+ */
+final class ObjectExplorer {
+    private static final NamespacedKey TINT_BIOME = NamespacedKey.minecraft("plains");
+    private static final int UNKNOWN_BLOCK_COLOR = 0x8A8A8A;
+    private static final String CAMERA_HINT = "Drag to orbit · Shift-drag to pan · Scroll to zoom · Page Up/Down cuts layers · R resets";
+    private static final String ONE_VARIANT_CARD = "one variant";
+    private static final String ALL_VARIANTS_CARD = "all variants";
+
+    private final Engine startEngine;
+    private final UUID worldId;
+    private final ObjectSource source;
+    private final ObjectBrowser browser;
+    private final ObjectViewport viewport = new ObjectViewport();
+    private final ObjectLayerCut layerCut = new ObjectLayerCut(shownLayers -> showLayerCut());
+    private final ObjectVariantPicker variantPicker = new ObjectVariantPicker(this::showVariant, this::showSeed, this::toggleComparing);
+    private final ObjectVariantGallery gallery = new ObjectVariantGallery(this::openVariant, this::redrawThumbnails);
+    private final CardLayout viewCards = new CardLayout();
+    private final JPanel views = new JPanel(viewCards);
+    private final JComponent viewWithOverlays;
+    private final ObjectOverviewPanel overview = new ObjectOverviewPanel(this::showSeeThrough);
+    private final StudioStatusBar statusBar = new StudioStatusBar();
+    private final ExecutorService loader = Executors.newSingleThreadExecutor(runnable -> {
+        Thread thread = new Thread(runnable, "Iris Object Loader");
+        thread.setDaemon(true);
+        thread.setPriority(Thread.MIN_PRIORITY);
+        return thread;
+    });
+    private final ExecutorService thumbnailPainter = Executors.newSingleThreadExecutor(runnable -> {
+        Thread thread = new Thread(runnable, "Iris Variant Thumbnails");
+        thread.setDaemon(true);
+        thread.setPriority(Thread.MIN_PRIORITY);
+        return thread;
+    });
+    private final AtomicLong objectRevision = new AtomicLong();
+    private final AtomicLong variantListRevision = new AtomicLong();
+    private final AtomicLong meshRevision = new AtomicLong();
+    private final Map<String, BlockModel> models = new ConcurrentHashMap<>();
+    private final Runnable hotloadHook = this::reloadPack;
+    private volatile BlockTextures textures;
+    private volatile BiomeTintColors tintColors;
+    private String shownKey;
+    private List<IrisObject> shownVariants = List.of();
+    private int shownVariantIndex;
+    private OptionalLong packSeed = OptionalLong.empty();
+    private OptionalLong shownSeed = OptionalLong.empty();
+    private boolean comparingVariants;
+    private long thumbnailsDrawnForRevision = -1;
+    private LoadedObject shown;
+    private ObjectMesh wholeMesh;
+    private Set<String> seeThroughTypes = Set.of();
+
+    ObjectExplorer(Engine engine, UUID worldId, ObjectSource source) {
+        this.startEngine = engine;
+        this.worldId = worldId;
+        this.source = source;
+        this.browser = new ObjectBrowser(source.noun(), this::showObject);
+        views.add(layerCut.floatingOver(viewport), ONE_VARIANT_CARD);
+        views.add(gallery, ALL_VARIANTS_CARD);
+        this.viewWithOverlays = variantPicker.floatingOver(views);
+        GuiHost.interruptOnPluginShutdown(loader);
+        GuiHost.interruptOnPluginShutdown(thumbnailPainter);
+        GuiHost.registerHotloadHook(hotloadHook);
+        statusBar.showPosition(CAMERA_HINT);
+        viewport.bindKey(KeyEvent.VK_PAGE_UP, "show-layer-above", () -> layerCut.stepBy(1));
+        viewport.bindKey(KeyEvent.VK_PAGE_DOWN, "hide-top-layer", () -> layerCut.stepBy(-1));
+        viewport.bindKey(KeyEvent.VK_OPEN_BRACKET, "previous-variant", () -> variantPicker.stepBy(-1));
+        viewport.bindKey(KeyEvent.VK_CLOSE_BRACKET, "next-variant", () -> variantPicker.stepBy(1));
+        viewport.bindKey(KeyEvent.VK_G, "compare-variants", this::toggleComparing);
+        gallery.bindKey(KeyEvent.VK_OPEN_BRACKET, "previous-variant", () -> variantPicker.stepBy(-1));
+        gallery.bindKey(KeyEvent.VK_CLOSE_BRACKET, "next-variant", () -> variantPicker.stepBy(1));
+        gallery.bindKey(KeyEvent.VK_G, "show-one-variant", this::toggleComparing);
+        gallery.bindKey(KeyEvent.VK_ESCAPE, "close-comparison", this::toggleComparing);
+    }
+
+    JComponent browser() {
+        return browser;
+    }
+
+    /**
+     * The 3D view with the slider that cuts away its top layers, or every variant side by side, under the bar that
+     * steps through variants and seeds.
+     */
+    JComponent view() {
+        return viewWithOverlays;
+    }
+
+    void setCoveredLeftWidth(int width) {
+        viewport.setCoveredLeftWidth(width);
+        gallery.setCoveredLeftWidth(width);
+        variantPicker.setCoveredLeftWidth(width);
+    }
+
+    JComponent overview() {
+        return overview;
+    }
+
+    StudioStatusBar statusBar() {
+        return statusBar;
+    }
+
+    void resetCamera() {
+        viewport.resetCamera();
+    }
+
+    // Textures load first, since the first object would otherwise be drawn in flat colours.
+    void open() {
+        viewport.showLoading("Loading Minecraft textures");
+        loader.execute(() -> {
+            loadTextures();
+            List<String> keys = objectKeys();
+            EventQueue.invokeLater(() -> showCatalog(keys));
+        });
+    }
+
+    void close() {
+        GuiHost.unregisterHotloadHook(hotloadHook);
+        objectRevision.incrementAndGet();
+        loader.shutdownNow();
+        thumbnailPainter.shutdownNow();
+        viewport.close();
+    }
+
+    private void loadTextures() {
+        try {
+            BlockTextures loaded = BlockTextures.shared().join();
+            tintColors = loaded.biomeColors().vanilla(TINT_BIOME);
+            textures = loaded;
+        } catch (RuntimeException unavailable) {
+            EventQueue.invokeLater(() -> statusBar.showError("Minecraft textures are unavailable, objects use plain colours"));
+        }
+    }
+
+    private List<String> objectKeys() {
+        return source.keys(engine().getData());
+    }
+
+    private void showCatalog(List<String> keys) {
+        statusBar.showActivity("");
+        browser.showObjects(keys);
+        String key = shownKey != null && keys.contains(shownKey) ? shownKey : browser.firstObject();
+        if (key == null) {
+            viewport.showEmptyState(source.emptyState());
+            overview.clear();
+            layerCut.showHeight(1);
+            if (comparingVariants) {
+                toggleComparing();
+            }
+            showVariantList(List.of(), OptionalLong.empty(), OptionalLong.empty(), 0);
+            return;
+        }
+        browser.select(key);
+        showObject(key);
+    }
+
+    /**
+     * Shows the first variant of the entry, baked from the pack's seed. The pack reloading the shown entry keeps the
+     * variant and the seed being looked at, unless the pack itself now sets another seed.
+     */
+    private void showObject(String key) {
+        boolean reloadingShownObject = key.equals(shownKey);
+        OptionalLong previousPackSeed = packSeed;
+        OptionalLong exploredSeed = shownSeed;
+        int variantIndex = reloadingShownObject ? shownVariantIndex : 0;
+        shownKey = key;
+        if (!reloadingShownObject) {
+            variantPicker.forgetTriedSeeds();
+            showVariantList(List.of(), OptionalLong.empty(), OptionalLong.empty(), 0);
+        }
+        long revision = startBaking(key);
+        loader.execute(() -> {
+            if (revision != objectRevision.get()) {
+                return;
+            }
+            OptionalLong pack = source.seed(key);
+            OptionalLong seed = reloadingShownObject && pack.equals(previousPackSeed) ? exploredSeed : pack;
+            loadVariants(revision, key, pack, seed, variantIndex);
+        });
+    }
+
+    // The seed shows at once, so stepping again continues from it even while this one bakes or fails.
+    private void showSeed(long seed) {
+        String key = shownKey;
+        OptionalLong pack = packSeed;
+        int variantIndex = shownVariantIndex;
+        shownSeed = OptionalLong.of(seed);
+        variantPicker.showSeed(shownSeed, pack);
+        long revision = startBaking(key + " with seed " + seed);
+        loader.execute(() -> {
+            if (revision == objectRevision.get()) {
+                loadVariants(revision, key, pack, OptionalLong.of(seed), variantIndex);
+            }
+        });
+    }
+
+    // On the loader thread.
+    private void loadVariants(long revision, String key, OptionalLong pack, OptionalLong seed, int preferredIndex) {
+        try {
+            IrisData data = engine().getData();
+            List<IrisObject> variants = seed.isPresent() ? source.variants(data, key, seed.getAsLong()) : source.variants(data, key);
+            if (variants.isEmpty()) {
+                throw new IllegalStateException("Nothing could be loaded for " + key);
+            }
+            int index = preferredIndex < variants.size() ? preferredIndex : 0;
+            LoadedObject loaded = load(variants.get(index));
+            EventQueue.invokeLater(() -> {
+                if (revision != objectRevision.get()) {
+                    return;
+                }
+                showVariantList(variants, pack, seed, index);
+                showLoaded(revision, loaded);
+            });
+        } catch (RuntimeException error) {
+            EventQueue.invokeLater(() -> showFailure(revision, key, error));
+        }
+    }
+
+    private void showVariantList(List<IrisObject> variants, OptionalLong pack, OptionalLong seed, int index) {
+        shownVariants = variants;
+        shownVariantIndex = index;
+        packSeed = pack;
+        shownSeed = seed;
+        variantListRevision.incrementAndGet();
+        variantPicker.showVariants(variants.size(), index);
+        variantPicker.showSeed(seed, pack);
+        if (!comparingVariants) {
+            return;
+        }
+        if (variants.isEmpty()) {
+            gallery.showLoading();
+        } else if (variants.size() == 1) {
+            toggleComparing();
+        } else {
+            drawThumbnails();
+        }
+    }
+
+    private void showVariant(int index) {
+        if (index >= shownVariants.size()) {
+            return;
+        }
+        shownVariantIndex = index;
+        gallery.select(index);
+        IrisObject variant = shownVariants.get(index);
+        long revision = startLoading(variant.getLoadKey());
+        loader.execute(() -> {
+            if (revision != objectRevision.get()) {
+                return;
+            }
+            LoadedObject loaded = load(variant);
+            EventQueue.invokeLater(() -> showLoaded(revision, loaded));
+        });
+    }
+
+    private void openVariant(int index) {
+        variantPicker.showVariants(shownVariants.size(), index);
+        showVariant(index);
+        toggleComparing();
+    }
+
+    private void toggleComparing() {
+        if (!comparingVariants && shownVariants.size() < 2) {
+            return;
+        }
+        comparingVariants = !comparingVariants;
+        variantPicker.showComparing(comparingVariants);
+        viewCards.show(views, comparingVariants ? ALL_VARIANTS_CARD : ONE_VARIANT_CARD);
+        if (comparingVariants) {
+            drawThumbnails();
+            gallery.requestFocusInWindow();
+        } else {
+            viewport.requestFocusInWindow();
+        }
+    }
+
+    private void redrawThumbnails() {
+        thumbnailsDrawnForRevision = -1;
+        if (comparingVariants) {
+            drawThumbnails();
+        }
+    }
+
+    /**
+     * Fills the side-by-side view with every shown variant, all drawn at the scale that fits the largest, so their
+     * sizes compare. Thumbnails arrive one at a time on their own thread, leaving the loader free for the 3D view.
+     */
+    private void drawThumbnails() {
+        long revision = variantListRevision.get();
+        if (revision == thumbnailsDrawnForRevision) {
+            return;
+        }
+        thumbnailsDrawnForRevision = revision;
+        List<IrisObject> variants = shownVariants;
+        gallery.showVariants(galleryHeading(), variants.size(), shownVariantIndex);
+        int size = gallery.thumbnailSize();
+        thumbnailPainter.execute(() -> {
+            List<ObjectMesh> meshes = new ArrayList<>();
+            for (IrisObject variant : variants) {
+                if (revision != variantListRevision.get()) {
+                    return;
+                }
+                meshes.add(ObjectMesh.build(visibleBlocks(variant), this::modelOf));
+            }
+            ObjectMesh.Bounds sizeToFit = largestSize(meshes);
+            for (int index = 0; index < meshes.size() && revision == variantListRevision.get(); index++) {
+                BufferedImage thumbnail = ObjectRenderer.renderThumbnail(meshes.get(index), sizeToFit, size, size);
+                int shownIndex = index;
+                EventQueue.invokeLater(() -> {
+                    if (revision == variantListRevision.get()) {
+                        gallery.showThumbnail(shownIndex, thumbnail);
+                    }
+                });
+            }
+        });
+    }
+
+    private String galleryHeading() {
+        return String.format(Locale.ROOT, "%s · %d variants%s", shownKey, shownVariants.size(), seedNote());
+    }
+
+    private static ObjectMesh.Bounds largestSize(List<ObjectMesh> meshes) {
+        int sizeX = 1;
+        int sizeY = 1;
+        int sizeZ = 1;
+        for (ObjectMesh mesh : meshes) {
+            sizeX = Math.max(sizeX, mesh.bounds().sizeX());
+            sizeY = Math.max(sizeY, mesh.bounds().sizeY());
+            sizeZ = Math.max(sizeZ, mesh.bounds().sizeZ());
+        }
+        return new ObjectMesh.Bounds(0, 0, 0, sizeX, sizeY, sizeZ);
+    }
+
+    // A new list of variants is on its way, so every thumbnail is outdated, unlike when stepping to another variant.
+    private long startBaking(String key) {
+        if (comparingVariants) {
+            gallery.showLoading();
+        }
+        return startLoading(key);
+    }
+
+    private long startLoading(String key) {
+        shown = null;
+        wholeMesh = null;
+        meshRevision.incrementAndGet();
+        viewport.showLoading("Loading " + key);
+        return objectRevision.incrementAndGet();
+    }
+
+    private LoadedObject load(IrisObject object) {
+        Map<BlockVector, BlockData> blocks = visibleBlocks(object);
+        ObjectMesh mesh = ObjectMesh.build(blocks, this::modelOf);
+        ObjectSummary summary = ObjectSummary.of(object.getLoadKey(), mesh.bounds(), blocks.values(), this::iconOf);
+        return new LoadedObject(blocks, mesh, summary);
+    }
+
+    private static Map<BlockVector, BlockData> visibleBlocks(IrisObject object) {
+        Map<BlockVector, BlockData> blocks = new HashMap<>();
+        object.getBlocks().forEach((position, block) -> {
+            if (!block.getMaterial().isAir()) {
+                blocks.put(position, block);
+            }
+        });
+        return blocks;
+    }
+
+
+    private void showLoaded(long revision, LoadedObject loaded) {
+        if (revision != objectRevision.get()) {
+            return;
+        }
+        shown = loaded;
+        wholeMesh = loaded.mesh();
+        seeThroughTypes = Set.of();
+        statusBar.showActivity("");
+        viewport.show(loaded.mesh());
+        overview.show(loaded.summary());
+        layerCut.showHeight(loaded.mesh().bounds().sizeY());
+        showMeshSummary(loaded.mesh());
+    }
+
+    private void showMeshSummary(ObjectMesh mesh) {
+        ObjectSummary summary = shown.summary();
+        String cut = layerCut.isCutting()
+                ? String.format(Locale.ROOT, " · showing layers 1-%d of %d", layerCut.shownLayerCount(), layerCut.layerCount())
+                : "";
+        statusBar.showSummary(String.format(Locale.ROOT, "%s%s · %,d blocks · %,d faces drawn%s",
+                summary.key(), seedNote(), summary.blockCount(), mesh.faceCount(), cut));
+    }
+
+    // A seed being tried is not in the pack until its "seed" field says so.
+    private String seedNote() {
+        if (shownSeed.isEmpty()) {
+            return "";
+        }
+        String note = " · seed " + shownSeed.getAsLong();
+        return shownSeed.equals(packSeed) ? note : note + " (the pack has " + packSeed.getAsLong() + ")";
+    }
+
+    private void showSeeThrough(Set<String> blockTypes) {
+        seeThroughTypes = blockTypes;
+        rebuildWholeMesh();
+    }
+
+    // Blocks behind see-through ones get their hidden faces back, so the mesh is built again.
+    private void rebuildWholeMesh() {
+        LoadedObject object = shown;
+        if (object == null) {
+            return;
+        }
+        long revision = meshRevision.incrementAndGet();
+        Set<String> seeThrough = seeThroughTypes;
+        loader.execute(() -> {
+            if (revision != meshRevision.get()) {
+                return;
+            }
+            ObjectMesh mesh = seeThrough.isEmpty()
+                    ? object.mesh()
+                    : ObjectMesh.build(object.blocks(), this::modelOf, object.mesh().bounds(),
+                    block -> seeThrough.contains(block.getMaterial().getKey().getKey()));
+            EventQueue.invokeLater(() -> {
+                if (revision == meshRevision.get() && shown == object) {
+                    wholeMesh = mesh;
+                    showLayerCut();
+                }
+            });
+        });
+    }
+
+    private void showLayerCut() {
+        if (wholeMesh == null) {
+            return;
+        }
+        int highestShownY = wholeMesh.bounds().minY() + layerCut.shownLayerCount() - 1;
+        ObjectMesh mesh = layerCut.isCutting() ? wholeMesh.cutAbove(highestShownY) : wholeMesh;
+        viewport.replaceMesh(mesh);
+        showMeshSummary(mesh);
+    }
+
+    private void showFailure(long revision, String key, Throwable error) {
+        if (revision != objectRevision.get()) {
+            return;
+        }
+        statusBar.showActivity("");
+        viewport.showMessage("Could not load " + key);
+        gallery.showMessage("Could not load " + key);
+        thumbnailsDrawnForRevision = -1;
+        overview.clear();
+        layerCut.showHeight(1);
+        statusBar.showError(error.getMessage() == null ? error.getClass().getSimpleName() : error.getMessage());
+    }
+
+    // The pack's files may have changed, so the list and the shown object are read again.
+    private void reloadPack() {
+        loader.execute(() -> {
+            List<String> keys = objectKeys();
+            EventQueue.invokeLater(() -> showCatalog(keys));
+        });
+    }
+
+    private Engine engine() {
+        Engine current = GuiHost.findEngine(worldId);
+        return current != null && !current.isClosed() ? current : startEngine;
+    }
+
+    private BlockModel modelOf(BlockData block) {
+        return models.computeIfAbsent(block.getAsString(false), state -> {
+            BlockTextures available = textures;
+            if (available == null) {
+                return BlockModel.solidColor(UNKNOWN_BLOCK_COLOR);
+            }
+            return available.model(block).map(this::withBiomeTint).orElseGet(() -> BlockModel.solidColor(UNKNOWN_BLOCK_COLOR));
+        });
+    }
+
+    private BufferedImage iconOf(BlockData block) {
+        BlockTextures available = textures;
+        if (available == null) {
+            return null;
+        }
+        return available.iconTexture(block).map(this::withBiomeTint).map(BlockTexture::toImage).orElse(null);
+    }
+
+    // Objects have no biome of their own, so grass and leaves get plains' colours.
+    private BlockModel withBiomeTint(BlockModel model) {
+        return model.withTextures(this::withBiomeTint);
+    }
+
+    private BlockTexture withBiomeTint(BlockTexture texture) {
+        BiomeTintColors colors = tintColors;
+        if (texture.biomeTint() == null || colors == null) {
+            return texture;
+        }
+        return texture.tinted(colors.colorAt(texture.biomeTint(), 0, 0));
+    }
+
+    private record LoadedObject(Map<BlockVector, BlockData> blocks, ObjectMesh mesh, ObjectSummary summary) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectLayerCut.java

@@ -0,0 +1,179 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.JComponent;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JSlider;
+import javax.swing.SwingConstants;
+import java.awt.AlphaComposite;
+import java.awt.BorderLayout;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.util.function.IntConsumer;
+
+/**
+ * A slim slider floating on the right of the 3D view that hides an object's top layers, to look inside buildings
+ * floor by floor. Most objects never need it, so it stays faint until the mouse comes near or a cut is active.
+ */
+final class ObjectLayerCut extends JPanel {
+    private static final long serialVersionUID = 4473820211915526120L;
+    private static final int PANEL_WIDTH = 30;
+    private static final int MAX_HEIGHT = 320;
+    private static final double HEIGHT_SHARE_OF_VIEW = 0.5D;
+    private static final int EDGE_MARGIN = 8;
+    private static final float FAINT_OPACITY = 0.28F;
+
+    private final JSlider slider = new JSlider(SwingConstants.VERTICAL, 1, 1, 1);
+    private final JLabel shownLayers = new JLabel(" ", SwingConstants.CENTER);
+    private final IntConsumer onLayersChanged;
+    private boolean resetting;
+    private boolean hovered;
+
+    /**
+     * @param onLayersChanged told how many layers from the bottom stay visible whenever the user moves the slider
+     */
+    ObjectLayerCut(IntConsumer onLayersChanged) {
+        super(new BorderLayout(0, StudioTheme.scale(4)));
+        this.onLayersChanged = onLayersChanged;
+        setOpaque(false);
+        setToolTipText("Hide the top layers to look inside · Page Up / Page Down");
+        shownLayers.setFont(StudioTheme.smallFont());
+        shownLayers.setForeground(StudioTheme.SECONDARY_TEXT);
+        slider.setOpaque(false);
+        slider.setFocusable(false);
+        slider.setToolTipText(getToolTipText());
+        slider.addChangeListener(event -> {
+            showLayerLabel();
+            if (!resetting) {
+                onLayersChanged.accept(slider.getValue());
+            }
+        });
+        MouseAdapter hover = new MouseAdapter() {
+            @Override
+            public void mouseEntered(MouseEvent event) {
+                setHovered(true);
+            }
+
+            @Override
+            public void mouseExited(MouseEvent event) {
+                setHovered(slider.getValueIsAdjusting());
+            }
+
+            @Override
+            public void mouseReleased(MouseEvent event) {
+                setHovered(slider.contains(event.getPoint()));
+            }
+        };
+        slider.addMouseListener(hover);
+        addMouseListener(hover);
+        add(shownLayers, BorderLayout.NORTH);
+        add(slider, BorderLayout.CENTER);
+        showHeight(1);
+    }
+
+    /**
+     * The view with this slider floating over its right edge, halfway down.
+     */
+    JComponent floatingOver(JComponent view) {
+        ObjectLayerCut cut = this;
+        JPanel stack = new JPanel(null) {
+            private static final long serialVersionUID = -1950381405658102347L;
+
+            // The slider overlaps the view, so the view may not repaint without the slider on top of it.
+            @Override
+            public boolean isOptimizedDrawingEnabled() {
+                return false;
+            }
+
+            @Override
+            public void doLayout() {
+                view.setBounds(0, 0, getWidth(), getHeight());
+                int width = StudioTheme.scale(PANEL_WIDTH);
+                int height = Math.min(StudioTheme.scale(MAX_HEIGHT), (int) (getHeight() * HEIGHT_SHARE_OF_VIEW));
+                cut.setBounds(getWidth() - width - StudioTheme.scale(EDGE_MARGIN), (getHeight() - height) / 2, width, height);
+            }
+        };
+        stack.add(cut);
+        stack.add(view);
+        return stack;
+    }
+
+    /**
+     * Shows every layer of a newly chosen object without telling anyone, since nothing is hidden yet.
+     */
+    void showHeight(int layers) {
+        resetting = true;
+        try {
+            slider.setMaximum(Math.max(1, layers));
+            slider.setValue(slider.getMaximum());
+        } finally {
+            resetting = false;
+        }
+        showLayerLabel();
+        setVisible(layers > 1);
+    }
+
+    void stepBy(int layers) {
+        if (isVisible()) {
+            slider.setValue(slider.getValue() + layers);
+        }
+    }
+
+    boolean isCutting() {
+        return slider.getValue() < slider.getMaximum();
+    }
+
+    int shownLayerCount() {
+        return slider.getValue();
+    }
+
+    int layerCount() {
+        return slider.getMaximum();
+    }
+
+    @Override
+    protected void paintChildren(Graphics graphics) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            if (!hovered && !isCutting()) {
+                canvas.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, FAINT_OPACITY));
+            }
+            super.paintChildren(canvas);
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private void setHovered(boolean nowHovered) {
+        if (hovered != nowHovered) {
+            hovered = nowHovered;
+            repaint();
+        }
+    }
+
+    private void showLayerLabel() {
+        shownLayers.setText(isCutting() ? Integer.toString(slider.getValue()) : " ");
+        repaint();
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectMesh.java

@@ -0,0 +1,243 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.BlockModel.Face;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.util.BlockVector;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+/**
+ * The faces of an object's blocks that can be seen from outside. A face is left out when the neighbour on its side
+ * covers that side, which is most of them in a large object. See-through faces, like water and stained glass, are
+ * kept apart because they are drawn last, blended over everything behind them. Top faces covered only by the block
+ * above are kept aside too, so the top layers can be cut away without building the mesh again; what is cut away stays
+ * as a faint ghost of the object's shape.
+ */
+record ObjectMesh(List<Quad> solidQuads, List<Quad> translucentQuads, List<Quad> cutAwayQuads, List<Quad> topsUnderBlockAbove,
+                  Bounds bounds) {
+    private static final double SEE_THROUGH_OPACITY = 0.22D;
+    private static final double FULL_OPACITY = 1D;
+    private static final double CUT_AWAY_OPACITY = 0.1D;
+
+    static ObjectMesh build(Map<BlockVector, BlockData> blocks, Function<BlockData, BlockModel> modelOf) {
+        return build(blocks, modelOf, Bounds.of(blocks.keySet()), block -> false);
+    }
+
+    /**
+     * @param bounds       the whole object's extent, kept when only part of it is drawn so the view does not jump
+     * @param isSeeThrough blocks drawn faintly, which hide nothing behind them, to look past them into the object
+     */
+    static ObjectMesh build(Map<BlockVector, BlockData> blocks, Function<BlockData, BlockModel> modelOf, Bounds bounds,
+                            Predicate<BlockData> isSeeThrough) {
+        List<Quad> solid = new ArrayList<>();
+        List<Quad> translucent = new ArrayList<>();
+        List<Quad> topsUnderBlockAbove = new ArrayList<>();
+        BlockGrid grid = new BlockGrid(blocks, modelOf, bounds, isSeeThrough);
+        for (BlockVector position : blocks.keySet()) {
+            int x = position.getBlockX();
+            int y = position.getBlockY();
+            int z = position.getBlockZ();
+            int cell = grid.cellAt(x, y, z);
+            for (Face face : grid.modelIn(cell).faces()) {
+                Quad quad = new Quad(face, x, y, z, grid.isSeeThroughIn(cell) ? SEE_THROUGH_OPACITY : FULL_OPACITY);
+                if (!grid.isHiddenByNeighbour(x, y, z, face)) {
+                    (quad.isBlended() ? translucent : solid).add(quad);
+                } else if (face.cullFace() == CubeFace.UP) {
+                    topsUnderBlockAbove.add(quad);
+                }
+            }
+        }
+        return new ObjectMesh(List.copyOf(solid), List.copyOf(translucent), List.of(), List.copyOf(topsUnderBlockAbove), bounds);
+    }
+
+    /**
+     * This mesh with the blocks above the given layer faded to a ghost of the object's shape, and the tops of that
+     * layer's blocks showing again. Quick enough to follow a slider as it moves.
+     */
+    ObjectMesh cutAbove(int highestShownY) {
+        List<Quad> solid = new ArrayList<>();
+        List<Quad> translucent = new ArrayList<>();
+        List<Quad> cutAway = new ArrayList<>();
+        for (Quad quad : solidQuads) {
+            keepOrCutAway(quad, highestShownY, solid, cutAway);
+        }
+        for (Quad quad : translucentQuads) {
+            keepOrCutAway(quad, highestShownY, translucent, cutAway);
+        }
+        for (Quad quad : topsUnderBlockAbove) {
+            if (quad.y() == highestShownY) {
+                (quad.isBlended() ? translucent : solid).add(quad);
+            }
+        }
+        return new ObjectMesh(solid, translucent, cutAway, List.of(), bounds);
+    }
+
+    private static void keepOrCutAway(Quad quad, int highestShownY, List<Quad> kept, List<Quad> cutAway) {
+        if (quad.y() <= highestShownY) {
+            kept.add(quad);
+        } else {
+            cutAway.add(quad.faded(CUT_AWAY_OPACITY));
+        }
+    }
+
+    boolean isEmpty() {
+        return solidQuads.isEmpty() && translucentQuads.isEmpty() && cutAwayQuads.isEmpty();
+    }
+
+    int faceCount() {
+        return solidQuads.size() + translucentQuads.size();
+    }
+
+    /**
+     * The object's blocks laid out in an array over its bounds, so finding a block's neighbours is quick. Looking them
+     * up by {@link BlockVector} in a map is slow, since its hash codes collide a lot.
+     */
+    private static final class BlockGrid {
+        private final Bounds bounds;
+        private final BlockData[] blocks;
+        private final BlockModel[] models;
+        private final boolean[] seeThrough;
+
+        BlockGrid(Map<BlockVector, BlockData> placed, Function<BlockData, BlockModel> modelOf, Bounds bounds,
+                  Predicate<BlockData> isSeeThrough) {
+            this.bounds = bounds;
+            int cells = bounds.sizeX() * bounds.sizeY() * bounds.sizeZ();
+            this.blocks = new BlockData[cells];
+            this.models = new BlockModel[cells];
+            this.seeThrough = new boolean[cells];
+            placed.forEach((position, block) -> {
+                int cell = cellAt(position.getBlockX(), position.getBlockY(), position.getBlockZ());
+                blocks[cell] = block;
+                models[cell] = modelOf.apply(block);
+                seeThrough[cell] = isSeeThrough.test(block);
+            });
+        }
+
+        int cellAt(int x, int y, int z) {
+            return ((y - bounds.minY()) * bounds.sizeZ() + (z - bounds.minZ())) * bounds.sizeX() + (x - bounds.minX());
+        }
+
+        BlockModel modelIn(int cell) {
+            return models[cell];
+        }
+
+        boolean isSeeThroughIn(int cell) {
+            return seeThrough[cell];
+        }
+
+        // Glass next to glass and water next to water hide the side between them too, as they do in the game. A
+        // see-through block only hides sides of other see-through blocks, so whatever it covers shows through it.
+        boolean isHiddenByNeighbour(int x, int y, int z, Face face) {
+            CubeFace side = face.cullFace();
+            if (side == null || !contains(x + side.stepX(), y + side.stepY(), z + side.stepZ())) {
+                return false;
+            }
+            int cell = cellAt(x, y, z);
+            int neighbourCell = cellAt(x + side.stepX(), y + side.stepY(), z + side.stepZ());
+            BlockData neighbour = blocks[neighbourCell];
+            if (neighbour == null || (seeThrough[neighbourCell] && !seeThrough[cell])) {
+                return false;
+            }
+            BlockModel neighbourModel = models[neighbourCell];
+            if (neighbourModel.coveredSides().contains(side.opposite())) {
+                return true;
+            }
+            return neighbour.getMaterial() == blocks[cell].getMaterial() && models[cell].hidesSameBlockSides()
+                    && neighbourModel.hidesSameBlockSides();
+        }
+
+        private boolean contains(int x, int y, int z) {
+            return x >= bounds.minX() && x < bounds.maxX() && y >= bounds.minY() && y < bounds.maxY()
+                    && z >= bounds.minZ() && z < bounds.maxZ();
+        }
+    }
+
+    /**
+     * A model face placed at a block in the object, drawn at the given opacity on top of its texture's own.
+     */
+    record Quad(Face face, int x, int y, int z, double opacity) {
+        boolean isBlended() {
+            return opacity < FULL_OPACITY || face.texture().isTranslucent();
+        }
+
+        Quad faded(double factor) {
+            return new Quad(face, x, y, z, opacity * factor);
+        }
+
+        double originX() {
+            return x + face.origin().x();
+        }
+
+        double originY() {
+            return y + face.origin().y();
+        }
+
+        double originZ() {
+            return z + face.origin().z();
+        }
+    }
+
+    /**
+     * The blocks' extent, with the maximum one past the last block so a single block spans one unit.
+     */
+    record Bounds(int minX, int minY, int minZ, int maxX, int maxY, int maxZ) {
+        private static final Bounds EMPTY = new Bounds(0, 0, 0, 1, 1, 1);
+
+        static Bounds of(Iterable<BlockVector> positions) {
+            int minX = Integer.MAX_VALUE;
+            int minY = Integer.MAX_VALUE;
+            int minZ = Integer.MAX_VALUE;
+            int maxX = Integer.MIN_VALUE;
+            int maxY = Integer.MIN_VALUE;
+            int maxZ = Integer.MIN_VALUE;
+            for (BlockVector position : positions) {
+                minX = Math.min(minX, position.getBlockX());
+                minY = Math.min(minY, position.getBlockY());
+                minZ = Math.min(minZ, position.getBlockZ());
+                maxX = Math.max(maxX, position.getBlockX() + 1);
+                maxY = Math.max(maxY, position.getBlockY() + 1);
+                maxZ = Math.max(maxZ, position.getBlockZ() + 1);
+            }
+            return minX == Integer.MAX_VALUE ? EMPTY : new Bounds(minX, minY, minZ, maxX, maxY, maxZ);
+        }
+
+        int sizeX() {
+            return maxX - minX;
+        }
+
+        int sizeY() {
+            return maxY - minY;
+        }
+
+        int sizeZ() {
+            return maxZ - minZ;
+        }
+
+        int largestSize() {
+            return Math.max(sizeX(), Math.max(sizeY(), sizeZ()));
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectOverviewPanel.java

@@ -0,0 +1,351 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.BorderFactory;
+import javax.swing.BoxLayout;
+import javax.swing.JButton;
+import javax.swing.SwingUtilities;
+import javax.swing.DefaultListCellRenderer;
+import javax.swing.DefaultListModel;
+import javax.swing.JLabel;
+import javax.swing.JList;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+import javax.swing.event.DocumentEvent;
+import javax.swing.event.DocumentListener;
+import java.awt.AlphaComposite;
+import java.awt.BorderLayout;
+import java.awt.Component;
+import java.awt.Composite;
+import java.awt.Cursor;
+import java.awt.Insets;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.GridLayout;
+import java.awt.RenderingHints;
+import java.awt.image.BufferedImage;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Set;
+import java.util.function.Consumer;
+
+/**
+ * The chosen object's size and the blocks it is made of, most used first, like the overview in Procedural Objects.
+ * Clicking a block makes it see-through in the 3D view, to look past walls into the object.
+ */
+final class ObjectOverviewPanel extends JPanel {
+    private static final long serialVersionUID = -8811407613645718290L;
+    private static final int PANEL_WIDTH = 280;
+    private static final int ROW_HEIGHT = 26;
+    private static final int ICON_SIZE = 16;
+    private static final int ICON_GAP = 8;
+    private static final int ROW_PADDING = 10;
+    private static final int SHARE_WIDTH = 92;
+    private static final int SHARE_BAR_HEIGHT = 4;
+    private static final float SEE_THROUGH_ICON_OPACITY = 0.3F;
+    private static final String SEE_THROUGH_HINT = "Click a block to see through it";
+
+    private final JLabel title = new JLabel(" ");
+    private final JLabel path = new JLabel(" ");
+    private final JLabel size = statValue();
+    private final JLabel blockCount = statValue();
+    private final JLabel blockTypes = statValue();
+    private final JLabel filled = statValue();
+    private final JTextField filterField = new JTextField();
+    private final DefaultListModel<ObjectSummary.BlockUse> rows = new DefaultListModel<>();
+    private final JList<ObjectSummary.BlockUse> list = new JList<>(rows) {
+        @Override
+        public boolean getScrollableTracksViewportWidth() {
+            return true;
+        }
+    };
+    private final JLabel seeThroughHint = new JLabel(SEE_THROUGH_HINT);
+    private final JButton showAllSolid = new JButton("Show all solid");
+    private final Set<String> seeThroughTypes = new LinkedHashSet<>();
+    private final Consumer<Set<String>> onSeeThroughChanged;
+    private ObjectSummary summary;
+
+    /**
+     * @param onSeeThroughChanged told which block types to draw see-through whenever the user changes them
+     */
+    ObjectOverviewPanel(Consumer<Set<String>> onSeeThroughChanged) {
+        super(new BorderLayout());
+        this.onSeeThroughChanged = onSeeThroughChanged;
+        setPreferredSize(StudioTheme.scaledSize(PANEL_WIDTH, 0));
+        setBorder(BorderFactory.createMatteBorder(0, 1, 0, 0, StudioTheme.SEPARATOR));
+        setBackground(StudioTheme.PANEL_BACKGROUND);
+        add(buildHeader(), BorderLayout.NORTH);
+        add(buildBlockList(), BorderLayout.CENTER);
+    }
+
+    void show(ObjectSummary nextSummary) {
+        summary = nextSummary;
+        title.setText(nextSummary.name());
+        path.setText(nextSummary.key());
+        path.setToolTipText(nextSummary.key());
+        size.setText(nextSummary.sizeX() + " × " + nextSummary.sizeY() + " × " + nextSummary.sizeZ());
+        blockCount.setText(formatCount(nextSummary.blockCount()));
+        blockTypes.setText(formatCount(nextSummary.blockUses().size()));
+        filled.setText(String.format(Locale.ROOT, "%.1f%%", nextSummary.filledFraction() * 100D));
+        seeThroughTypes.clear();
+        showSeeThroughState();
+        refilter();
+    }
+
+    void clear() {
+        summary = null;
+        title.setText(" ");
+        path.setText(" ");
+        for (JLabel value : List.of(size, blockCount, blockTypes, filled)) {
+            value.setText("—");
+        }
+        rows.clear();
+        seeThroughTypes.clear();
+        showSeeThroughState();
+    }
+
+    private JPanel buildHeader() {
+        JPanel header = new JPanel();
+        header.setLayout(new BoxLayout(header, BoxLayout.Y_AXIS));
+        header.setOpaque(false);
+        header.setBorder(StudioTheme.emptyBorder(12, 16, 8, 16));
+        title.setFont(StudioTheme.titleFont());
+        path.setFont(StudioTheme.smallFont());
+        path.setForeground(StudioTheme.SECONDARY_TEXT);
+        header.add(leftAligned(title));
+        header.add(leftAligned(path));
+
+        JPanel stats = new JPanel(new GridLayout(2, 2, StudioTheme.scale(12), StudioTheme.scale(8)));
+        stats.setOpaque(false);
+        stats.setBorder(StudioTheme.emptyBorder(12, 0, 4, 0));
+        stats.add(stat("Size · X × Y × Z", size));
+        stats.add(stat("Blocks", blockCount));
+        stats.add(stat("Block types", blockTypes));
+        stats.add(stat("Filled volume", filled));
+        filled.setToolTipText("How much of the object's bounding box its blocks fill");
+        header.add(leftAligned(stats));
+        clear();
+        return header;
+    }
+
+    private JPanel buildBlockList() {
+        JPanel blocks = new JPanel(new BorderLayout());
+        blocks.setOpaque(false);
+        StudioToolbar.makeSearchField(filterField, "Find a block...");
+        filterField.getDocument().addDocumentListener(new DocumentListener() {
+            @Override
+            public void insertUpdate(DocumentEvent event) {
+                refilter();
+            }
+
+            @Override
+            public void removeUpdate(DocumentEvent event) {
+                refilter();
+            }
+
+            @Override
+            public void changedUpdate(DocumentEvent event) {
+                refilter();
+            }
+        });
+        list.setFocusable(false);
+        list.setFixedCellHeight(StudioTheme.scale(ROW_HEIGHT));
+        list.setCellRenderer(new BlockUseRenderer());
+        list.setBackground(StudioTheme.PANEL_BACKGROUND);
+        list.setBorder(StudioTheme.emptyBorder(0, 6, 4, 6));
+        list.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
+        list.addMouseListener(new MouseAdapter() {
+            @Override
+            public void mouseClicked(MouseEvent event) {
+                int row = list.locationToIndex(event.getPoint());
+                if (SwingUtilities.isLeftMouseButton(event) && row >= 0 && list.getCellBounds(row, row).contains(event.getPoint())) {
+                    toggleSeeThrough(rows.get(row).blockType());
+                }
+            }
+        });
+        JPanel top = new JPanel();
+        top.setLayout(new BoxLayout(top, BoxLayout.Y_AXIS));
+        top.setOpaque(false);
+        top.add(leftAligned(StudioToolbar.padded(filterField, 4, 12, 4, 12)));
+        top.add(leftAligned(StudioToolbar.padded(seeThroughRow(), 0, 14, 6, 12)));
+        blocks.add(top, BorderLayout.NORTH);
+        blocks.add(StudioToolbar.scroll(list), BorderLayout.CENTER);
+        return blocks;
+    }
+
+    private JPanel seeThroughRow() {
+        seeThroughHint.setFont(StudioTheme.smallFont());
+        seeThroughHint.setForeground(StudioTheme.MUTED_TEXT);
+        showAllSolid.setFont(StudioTheme.smallFont());
+        showAllSolid.setForeground(StudioTheme.LINK);
+        showAllSolid.setBorderPainted(false);
+        showAllSolid.setContentAreaFilled(false);
+        showAllSolid.setFocusable(false);
+        showAllSolid.setMargin(new Insets(0, 0, 0, 0));
+        showAllSolid.setBorder(BorderFactory.createEmptyBorder());
+        showAllSolid.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
+        showAllSolid.addActionListener(event -> {
+            seeThroughTypes.clear();
+            seeThroughChanged();
+        });
+        JPanel row = new JPanel(new BorderLayout());
+        row.setOpaque(false);
+        row.add(seeThroughHint, BorderLayout.CENTER);
+        row.add(showAllSolid, BorderLayout.EAST);
+        showSeeThroughState();
+        return row;
+    }
+
+    private void toggleSeeThrough(String blockType) {
+        if (!seeThroughTypes.remove(blockType)) {
+            seeThroughTypes.add(blockType);
+        }
+        seeThroughChanged();
+    }
+
+    private void seeThroughChanged() {
+        showSeeThroughState();
+        list.repaint();
+        onSeeThroughChanged.accept(Set.copyOf(seeThroughTypes));
+    }
+
+    private void showSeeThroughState() {
+        int count = seeThroughTypes.size();
+        seeThroughHint.setText(count == 0 ? SEE_THROUGH_HINT : count == 1 ? "1 block see-through" : count + " blocks see-through");
+        showAllSolid.setVisible(count > 0);
+    }
+
+    private void refilter() {
+        rows.clear();
+        if (summary == null) {
+            return;
+        }
+        String filter = filterField.getText().trim().toLowerCase(Locale.ROOT).replace(' ', '_');
+        for (ObjectSummary.BlockUse use : summary.blockUses()) {
+            if (use.blockType().contains(filter)) {
+                rows.addElement(use);
+            }
+        }
+    }
+
+    private static JPanel stat(String label, JLabel value) {
+        JPanel stat = new JPanel(new BorderLayout());
+        stat.setOpaque(false);
+        JLabel name = new JLabel(label);
+        name.setFont(StudioTheme.smallFont());
+        name.setForeground(StudioTheme.MUTED_TEXT);
+        stat.add(name, BorderLayout.NORTH);
+        stat.add(value, BorderLayout.CENTER);
+        return stat;
+    }
+
+    private static JLabel statValue() {
+        JLabel value = new JLabel("—");
+        value.setFont(StudioTheme.boldFont());
+        return value;
+    }
+
+    private static Component leftAligned(JPanel panel) {
+        panel.setAlignmentX(LEFT_ALIGNMENT);
+        return panel;
+    }
+
+    private static Component leftAligned(JLabel label) {
+        label.setAlignmentX(LEFT_ALIGNMENT);
+        return label;
+    }
+
+    private static String formatCount(int count) {
+        return String.format(Locale.ROOT, "%,d", count);
+    }
+
+    private final class BlockUseRenderer extends DefaultListCellRenderer {
+        private static final long serialVersionUID = 2785337045812613941L;
+        private transient BufferedImage icon;
+        private boolean seeThrough;
+        private double share;
+        private String percent = "";
+
+        @Override
+        public Component getListCellRendererComponent(JList<?> owner, Object value, int index, boolean selected, boolean focused) {
+            ObjectSummary.BlockUse use = (ObjectSummary.BlockUse) value;
+            super.getListCellRendererComponent(owner, use.blockType(), index, false, false);
+            seeThrough = seeThroughTypes.contains(use.blockType());
+            setFont(StudioTheme.font());
+            setForeground(seeThrough ? StudioTheme.MUTED_TEXT : StudioTheme.TEXT);
+            setBorder(StudioTheme.emptyBorder(0, ROW_PADDING + ICON_SIZE + ICON_GAP, 0, ROW_PADDING + SHARE_WIDTH));
+            setToolTipText(use.blockType() + " · " + formatCount(use.count()) + " blocks · click to "
+                    + (seeThrough ? "make solid again" : "see through it"));
+            icon = use.icon();
+            share = summary == null || summary.blockCount() == 0 ? 0D : use.count() / (double) summary.blockCount();
+            percent = share > 0D && share < 0.001D ? "<0.1%" : String.format(Locale.ROOT, "%.1f%%", share * 100D);
+            return this;
+        }
+
+        @Override
+        protected void paintComponent(Graphics graphics) {
+            super.paintComponent(graphics);
+            Graphics2D canvas = (Graphics2D) graphics.create();
+            try {
+                int iconSize = StudioTheme.scale(ICON_SIZE);
+                int iconX = StudioTheme.scale(ROW_PADDING);
+                int iconY = (getHeight() - iconSize) / 2;
+                if (icon != null) {
+                    canvas.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR);
+                    Composite solid = canvas.getComposite();
+                    if (seeThrough) {
+                        canvas.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, SEE_THROUGH_ICON_OPACITY));
+                    }
+                    canvas.drawImage(icon, iconX, iconY, iconSize, iconSize, null);
+                    canvas.setComposite(solid);
+                } else {
+                    canvas.setColor(StudioTheme.CONTROL_BORDER);
+                    canvas.drawRect(iconX, iconY, iconSize - 1, iconSize - 1);
+                }
+                drawShare(canvas);
+            } finally {
+                canvas.dispose();
+            }
+        }
+
+        private void drawShare(Graphics2D canvas) {
+            canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+            canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+            canvas.setFont(StudioTheme.smallFont());
+            int padding = StudioTheme.scale(ROW_PADDING);
+            int percentWidth = canvas.getFontMetrics().stringWidth("100.0%");
+            int barWidth = StudioTheme.scale(SHARE_WIDTH) - percentWidth - StudioTheme.scale(6);
+            int barX = getWidth() - padding - StudioTheme.scale(SHARE_WIDTH);
+            int barHeight = StudioTheme.scale(SHARE_BAR_HEIGHT);
+            int barY = (getHeight() - barHeight) / 2;
+            canvas.setColor(StudioTheme.HOVER_BACKGROUND);
+            canvas.fillRoundRect(barX, barY, barWidth, barHeight, barHeight, barHeight);
+            canvas.setColor(seeThrough ? StudioTheme.CONTROL_BORDER : StudioTheme.ACCENT);
+            canvas.fillRoundRect(barX, barY, Math.max(barHeight, (int) Math.round(barWidth * share)), barHeight, barHeight, barHeight);
+            canvas.setColor(StudioTheme.SECONDARY_TEXT);
+            int textWidth = canvas.getFontMetrics().stringWidth(percent);
+            int baseline = (getHeight() + canvas.getFontMetrics().getAscent() - canvas.getFontMetrics().getDescent()) / 2;
+            canvas.drawString(percent, getWidth() - padding - textWidth, baseline);
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectRenderer.java

@@ -0,0 +1,356 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.BlockModel.Face;
+import com.volmit.iris.core.gui.BlockModel.TextureMapping;
+import com.volmit.iris.core.gui.BlockTextures.BlockTexture;
+
+import java.awt.Color;
+import java.awt.image.BufferedImage;
+import java.awt.image.DataBufferInt;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * Draws an object mesh with an orthographic camera into a picture, without a graphics card: each quad is filled pixel
+ * by pixel, and a depth buffer keeps the nearest one. A cut-away part's faint ghost only fills pixels the object
+ * leaves empty, so it never hazes over what is shown. See-through quads come last, farthest first, each blended over
+ * what is already drawn.
+ */
+final class ObjectRenderer {
+    private static final Color GRID = new ThemeColor(0xE3E4E8, 0x34373C);
+    private static final int GRID_LINES_PER_SIDE = 25;
+    private static final double GRID_REACH = 0.7D;
+    private static final double GRID_BELOW_OBJECT = 0.035D;
+    // Shared quad edges land exactly on pixel centres now and then; a little overlap keeps them from leaving cracks.
+    private static final double EDGE_TOLERANCE = 1e-6D;
+    private static final double EDGE_ON_DETERMINANT = 1e-9D;
+    // A face's own texels end a hair inside its UV rectangle, so rounding never picks the texel next to it.
+    private static final double TEXEL_EDGE_MARGIN = 1e-6D;
+    private static final double FULL_ALPHA = 255D;
+    // Zoom 2 fills the picture with the object's bounding box; thumbnails keep a hair of margin around it.
+    private static final ObjectCamera THUMBNAIL_CAMERA = new ObjectCamera(ObjectCamera.START.yaw(), ObjectCamera.START.pitch(), 1.9D, 0D, 0D);
+
+    private final int width;
+    private final int height;
+    private final int[] pixels;
+    private final double[] depths;
+    private final boolean[] showsObject;
+    private final Projection projection;
+    private final int gridColor = GRID.getRGB() & 0xFFFFFF;
+
+    private ObjectRenderer(BufferedImage image, Projection projection) {
+        this.width = image.getWidth();
+        this.height = image.getHeight();
+        this.pixels = ((DataBufferInt) image.getRaster().getDataBuffer()).getData();
+        this.depths = new double[pixels.length];
+        this.showsObject = new boolean[pixels.length];
+        this.projection = projection;
+        Arrays.fill(pixels, StudioTheme.EDITOR_BACKGROUND.getRGB() & 0xFFFFFF);
+        Arrays.fill(depths, Double.NEGATIVE_INFINITY);
+    }
+
+    /**
+     * @param coveredLeftWidth how much of the picture's left side something floats over, so the object is centred and
+     *                         fitted in the rest
+     */
+    static BufferedImage render(ObjectMesh mesh, ObjectCamera camera, int width, int height, int coveredLeftWidth) {
+        BufferedImage image = blankImage(width, height);
+        int covered = Math.max(0, Math.min(image.getWidth() - 1, coveredLeftWidth));
+        ObjectRenderer renderer = new ObjectRenderer(image, new Projection(mesh.bounds(), mesh.bounds(), camera, image.getWidth(), image.getHeight(), covered));
+        renderer.drawGrid(mesh.bounds());
+        renderer.drawMesh(mesh);
+        return image;
+    }
+
+    /**
+     * Draws {@code mesh} from the starting angle, without the floor grid, at the scale that fits an object of
+     * {@code sizeToFit}. Objects drawn with the same size compare at their true sizes, standing on the same ground.
+     */
+    static BufferedImage renderThumbnail(ObjectMesh mesh, ObjectMesh.Bounds sizeToFit, int width, int height) {
+        BufferedImage image = blankImage(width, height);
+        new ObjectRenderer(image, new Projection(mesh.bounds(), sizeToFit, THUMBNAIL_CAMERA, image.getWidth(), image.getHeight(), 0)).drawMesh(mesh);
+        return image;
+    }
+
+    private static BufferedImage blankImage(int width, int height) {
+        return new BufferedImage(Math.max(1, width), Math.max(1, height), BufferedImage.TYPE_INT_RGB);
+    }
+
+    private void drawMesh(ObjectMesh mesh) {
+        for (ObjectMesh.Quad quad : mesh.solidQuads()) {
+            drawQuad(quad, Pass.SOLID);
+        }
+        for (ObjectMesh.Quad quad : mesh.cutAwayQuads()) {
+            drawQuad(quad, Pass.CUT_AWAY_GHOST);
+        }
+        for (ObjectMesh.Quad quad : farthestFirst(mesh.translucentQuads())) {
+            drawQuad(quad, Pass.BLENDED);
+        }
+    }
+
+    private List<ObjectMesh.Quad> farthestFirst(List<ObjectMesh.Quad> quads) {
+        List<ObjectMesh.Quad> sorted = new ArrayList<>(quads);
+        sorted.sort(Comparator.comparingDouble(this::centerDepth));
+        return sorted;
+    }
+
+    private double centerDepth(ObjectMesh.Quad quad) {
+        Face face = quad.face();
+        return projection.depth(
+                quad.originX() + (face.edgeU().x() + face.edgeV().x()) / 2D,
+                quad.originY() + (face.edgeU().y() + face.edgeV().y()) / 2D,
+                quad.originZ() + (face.edgeU().z() + face.edgeV().z()) / 2D);
+    }
+
+    private void drawGrid(ObjectMesh.Bounds bounds) {
+        int reach = (int) Math.ceil(bounds.largestSize() * GRID_REACH);
+        int step = Math.max(1, (int) Math.ceil(reach / (double) GRID_LINES_PER_SIDE));
+        double floor = bounds.minY() - GRID_BELOW_OBJECT;
+        int centerX = Math.floorDiv(bounds.minX() + bounds.maxX(), 2);
+        int centerZ = Math.floorDiv(bounds.minZ() + bounds.maxZ(), 2);
+        for (int offset = -reach; offset <= reach; offset += step) {
+            drawLine(centerX + offset, floor, centerZ - reach, centerX + offset, floor, centerZ + reach);
+            drawLine(centerX - reach, floor, centerZ + offset, centerX + reach, floor, centerZ + offset);
+        }
+    }
+
+    private void drawLine(double fromX, double fromY, double fromZ, double toX, double toY, double toZ) {
+        double startX = projection.screenX(fromX, fromY, fromZ);
+        double startY = projection.screenY(fromX, fromY, fromZ);
+        double startDepth = projection.depth(fromX, fromY, fromZ);
+        double endX = projection.screenX(toX, toY, toZ);
+        double endY = projection.screenY(toX, toY, toZ);
+        double endDepth = projection.depth(toX, toY, toZ);
+        int steps = (int) Math.ceil(Math.max(Math.abs(endX - startX), Math.abs(endY - startY)));
+        for (int step = 0; step <= steps; step++) {
+            double progress = steps == 0 ? 0D : step / (double) steps;
+            int x = (int) (startX + (endX - startX) * progress);
+            int y = (int) (startY + (endY - startY) * progress);
+            if (x < 0 || y < 0 || x >= width || y >= height) {
+                continue;
+            }
+            int index = y * width + x;
+            double depth = startDepth + (endDepth - startDepth) * progress;
+            if (depth > depths[index]) {
+                depths[index] = depth;
+                pixels[index] = gridColor;
+            }
+        }
+    }
+
+    // Later faces win ties, so an overlay drawn on the same box, like grass on a grass block's side, shows on top.
+    private void drawQuad(ObjectMesh.Quad quad, Pass pass) {
+        Face face = quad.face();
+        if (!projection.facesCamera(face.normal().x(), face.normal().y(), face.normal().z())) {
+            return;
+        }
+        Vec3 u = face.edgeU();
+        Vec3 v = face.edgeV();
+        double originX = projection.screenX(quad.originX(), quad.originY(), quad.originZ());
+        double originY = projection.screenY(quad.originX(), quad.originY(), quad.originZ());
+        double originDepth = projection.depth(quad.originX(), quad.originY(), quad.originZ());
+        double edgeUX = projection.screenStepX(u.x(), u.z());
+        double edgeUY = projection.screenStepY(u.x(), u.y(), u.z());
+        double edgeUDepth = projection.depthStep(u.x(), u.y(), u.z());
+        double edgeVX = projection.screenStepX(v.x(), v.z());
+        double edgeVY = projection.screenStepY(v.x(), v.y(), v.z());
+        double edgeVDepth = projection.depthStep(v.x(), v.y(), v.z());
+        double determinant = edgeUX * edgeVY - edgeUY * edgeVX;
+        if (Math.abs(determinant) < EDGE_ON_DETERMINANT) {
+            return;
+        }
+
+        int left = Math.max(0, (int) Math.floor(min4(originX, originX + edgeUX, originX + edgeVX, originX + edgeUX + edgeVX)));
+        int right = Math.min(width - 1, (int) Math.ceil(max4(originX, originX + edgeUX, originX + edgeVX, originX + edgeUX + edgeVX)));
+        int top = Math.max(0, (int) Math.floor(min4(originY, originY + edgeUY, originY + edgeVY, originY + edgeUY + edgeVY)));
+        int bottom = Math.min(height - 1, (int) Math.ceil(max4(originY, originY + edgeUY, originY + edgeVY, originY + edgeUY + edgeVY)));
+        if (left > right || top > bottom) {
+            return;
+        }
+
+        BlockTexture texture = face.texture();
+        TextureMapping mapping = face.mapping();
+        TexelRange columns = TexelRange.of(mapping.u(), mapping.uAlongU(), mapping.uAlongV(), texture.width());
+        TexelRange rows = TexelRange.of(mapping.v(), mapping.vAlongU(), mapping.vAlongV(), texture.height());
+        int[] texels = texture.pixels();
+        boolean[] opaque = texture.opaque();
+        int[] alphas = texture.alphas();
+        double shade = face.shade();
+        double alongUPerPixelX = edgeVY / determinant;
+        double alongVPerPixelX = -edgeUY / determinant;
+        for (int y = top; y <= bottom; y++) {
+            double offsetX = left + 0.5D - originX;
+            double offsetY = y + 0.5D - originY;
+            double alongU = (offsetX * edgeVY - offsetY * edgeVX) / determinant;
+            double alongV = (offsetY * edgeUX - offsetX * edgeUY) / determinant;
+            int rowStart = y * width;
+            for (int x = left; x <= right; x++, alongU += alongUPerPixelX, alongV += alongVPerPixelX) {
+                if (alongU < -EDGE_TOLERANCE || alongU > 1D + EDGE_TOLERANCE || alongV < -EDGE_TOLERANCE || alongV > 1D + EDGE_TOLERANCE) {
+                    continue;
+                }
+                int index = rowStart + x;
+                double depth = originDepth + alongU * edgeUDepth + alongV * edgeVDepth;
+                if (depth < depths[index] || (pass == Pass.CUT_AWAY_GHOST && showsObject[index])) {
+                    continue;
+                }
+                int texelX = columns.texelAt(mapping.u() + alongU * mapping.uAlongU() + alongV * mapping.uAlongV());
+                int texelY = rows.texelAt(mapping.v() + alongU * mapping.vAlongU() + alongV * mapping.vAlongV());
+                int texel = texelY * texture.width() + texelX;
+                if (!opaque[texel]) {
+                    continue;
+                }
+                int color = BlockPreviewColors.shade(texels[texel], shade);
+                if (pass != Pass.SOLID) {
+                    pixels[index] = blend(color, pixels[index], (alphas == null ? 1D : alphas[texel] / FULL_ALPHA) * quad.opacity());
+                    continue;
+                }
+                depths[index] = depth;
+                pixels[index] = color;
+                showsObject[index] = true;
+            }
+        }
+    }
+
+    private static int blend(int over, int under, double coverage) {
+        return blendChannel(over, under, coverage, 16) << 16 | blendChannel(over, under, coverage, 8) << 8 | blendChannel(over, under, coverage, 0);
+    }
+
+    private static int blendChannel(int over, int under, double coverage, int shift) {
+        return (int) Math.round(((over >>> shift) & 0xFF) * coverage + ((under >>> shift) & 0xFF) * (1D - coverage));
+    }
+
+    private static double min4(double a, double b, double c, double d) {
+        return Math.min(Math.min(a, b), Math.min(c, d));
+    }
+
+    private static double max4(double a, double b, double c, double d) {
+        return Math.max(Math.max(a, b), Math.max(c, d));
+    }
+
+    /**
+     * The texels a face covers along one texture axis, so a pixel on the face's edge never takes its neighbour's.
+     */
+    private record TexelRange(int first, int last, int size) {
+        static TexelRange of(double start, double alongU, double alongV, int size) {
+            double low = start + Math.min(0D, alongU) + Math.min(0D, alongV);
+            double high = start + Math.max(0D, alongU) + Math.max(0D, alongV);
+            int first = clamp((int) Math.floor(low * size + TEXEL_EDGE_MARGIN), size);
+            int last = Math.max(first, clamp((int) Math.ceil(high * size - TEXEL_EDGE_MARGIN) - 1, size));
+            return new TexelRange(first, last, size);
+        }
+
+        int texelAt(double fraction) {
+            int texel = (int) Math.floor(fraction * size);
+            return texel < first ? first : Math.min(texel, last);
+        }
+
+        private static int clamp(int texel, int size) {
+            return Math.max(0, Math.min(size - 1, texel));
+        }
+    }
+
+    /**
+     * Turns block positions into pixels. Larger depth is nearer the camera.
+     */
+    private static final class Projection {
+        private final double centerX;
+        private final double centerY;
+        private final double centerZ;
+        private final double cosYaw;
+        private final double sinYaw;
+        private final double cosPitch;
+        private final double sinPitch;
+        private final double pixelsPerBlock;
+        private final double screenCenterX;
+        private final double screenCenterY;
+
+        /**
+         * @param shown    the object drawn, centred across and standing where an object of {@code scaledAs} would
+         * @param scaledAs the size that is fitted to the view
+         */
+        private Projection(ObjectMesh.Bounds shown, ObjectMesh.Bounds scaledAs, ObjectCamera camera, int width, int height, int coveredLeftWidth) {
+            this.centerX = (shown.minX() + shown.maxX()) / 2D;
+            this.centerY = shown.minY() + scaledAs.sizeY() / 2D;
+            this.centerZ = (shown.minZ() + shown.maxZ()) / 2D;
+            this.cosYaw = Math.cos(camera.yaw());
+            this.sinYaw = Math.sin(camera.yaw());
+            this.cosPitch = Math.cos(camera.pitch());
+            this.sinPitch = Math.sin(camera.pitch());
+            int visibleWidth = width - coveredLeftWidth;
+            double fit = fitAtStartingAngle(scaledAs, visibleWidth / (double) height);
+            this.pixelsPerBlock = camera.zoom() * fit * height / 2D / scaledAs.largestSize();
+            this.screenCenterX = coveredLeftWidth + visibleWidth / 2D + camera.panX() * visibleWidth / 2D;
+            this.screenCenterY = height / 2D - camera.panY() * height / 2D;
+        }
+
+        // How far to scale the object down so it fits the view at the starting angle; orbiting keeps the scale.
+        private static double fitAtStartingAngle(ObjectMesh.Bounds bounds, double aspect) {
+            double size = bounds.largestSize();
+            double width = bounds.sizeX() / size;
+            double height = bounds.sizeY() / size;
+            double depth = bounds.sizeZ() / size;
+            double yaw = ObjectCamera.START.yaw();
+            double pitch = ObjectCamera.START.pitch();
+            double projectedWidth = Math.abs(Math.cos(yaw)) * width + Math.abs(Math.sin(yaw)) * depth;
+            double projectedDepth = Math.abs(Math.sin(yaw)) * width + Math.abs(Math.cos(yaw)) * depth;
+            double projectedHeight = Math.abs(Math.cos(pitch)) * height + Math.abs(Math.sin(pitch)) * projectedDepth;
+            return Math.min(1D, Math.min(aspect / projectedWidth, 1D / projectedHeight));
+        }
+
+        double screenX(double x, double y, double z) {
+            return screenCenterX + screenStepX(x - centerX, z - centerZ);
+        }
+
+        double screenY(double x, double y, double z) {
+            return screenCenterY + screenStepY(x - centerX, y - centerY, z - centerZ);
+        }
+
+        double depth(double x, double y, double z) {
+            return depthStep(x - centerX, y - centerY, z - centerZ);
+        }
+
+        double screenStepX(double x, double z) {
+            return (cosYaw * x - sinYaw * z) * pixelsPerBlock;
+        }
+
+        double screenStepY(double x, double y, double z) {
+            double towardCamera = sinYaw * x + cosYaw * z;
+            return -(cosPitch * y - sinPitch * towardCamera) * pixelsPerBlock;
+        }
+
+        double depthStep(double x, double y, double z) {
+            double towardCamera = sinYaw * x + cosYaw * z;
+            return sinPitch * y + cosPitch * towardCamera;
+        }
+
+        boolean facesCamera(double normalX, double normalY, double normalZ) {
+            return depthStep(normalX, normalY, normalZ) > 0D;
+        }
+    }
+
+    private enum Pass {
+        SOLID,
+        CUT_AWAY_GHOST,
+        BLENDED
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectSeedChooser.java

@@ -0,0 +1,160 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.volmit.iris.core.gui;
+
+import javax.swing.DefaultComboBoxModel;
+import javax.swing.DefaultListCellRenderer;
+import javax.swing.JComboBox;
+import javax.swing.JLabel;
+import javax.swing.JList;
+import javax.swing.JPanel;
+import javax.swing.UIManager;
+import java.awt.BorderLayout;
+import java.awt.Component;
+import java.awt.Dimension;
+import java.awt.EventQueue;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.OptionalLong;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.LongConsumer;
+
+/**
+ * Where the seed of a procedural object's variants is chosen: typed in, picked again from the seeds tried on this
+ * object with the pack's own first, or rerolled at random. It keeps its size whatever it shows, so the bar it sits in
+ * never shifts under the mouse.
+ */
+final class ObjectSeedChooser extends JPanel {
+    private static final long serialVersionUID = 3127745038254406118L;
+    private static final int FIELD_WIDTH = 120;
+    private static final int TRIED_SEEDS_KEPT = 12;
+    // Small enough to read back and type, and far more seeds than anyone tries.
+    private static final int RANDOM_SEED_BOUND = 1_000_000;
+
+    private final JComboBox<Long> seeds = new JComboBox<>();
+    private final LongConsumer onSeedChosen;
+    private final List<Long> triedSeedsNewestFirst = new ArrayList<>();
+    private OptionalLong packSeed = OptionalLong.empty();
+    private long shownSeed;
+    private boolean showingSeeds;
+
+    /**
+     * @param onSeedChosen told the seed to bake the variants from whenever the user chooses another one
+     */
+    ObjectSeedChooser(LongConsumer onSeedChosen) {
+        super(new BorderLayout(StudioTheme.scale(4), 0));
+        this.onSeedChosen = onSeedChosen;
+        setOpaque(false);
+        JLabel label = new JLabel("Seed");
+        label.setFont(StudioTheme.smallFont());
+        label.setForeground(StudioTheme.SECONDARY_TEXT);
+        seeds.setEditable(true);
+        seeds.setFont(StudioTheme.smallFont());
+        seeds.setToolTipText("Type a seed and press Enter, or pick one tried before");
+        seeds.setRenderer(new PackSeedMarker());
+        seeds.setPreferredSize(new Dimension(StudioTheme.scale(FIELD_WIDTH), seeds.getPreferredSize().height));
+        seeds.addActionListener(event -> {
+            if (!showingSeeds) {
+                EventQueue.invokeLater(this::chooseEnteredSeed);
+            }
+        });
+        add(label, BorderLayout.WEST);
+        add(seeds, BorderLayout.CENTER);
+        add(StudioToolbar.button("Reroll", "Bake the variants from a random seed", this::reroll), BorderLayout.EAST);
+    }
+
+    /** Starts a new object's list of tried seeds. */
+    void forgetTriedSeeds() {
+        triedSeedsNewestFirst.clear();
+    }
+
+    void showSeed(long shown, OptionalLong pack) {
+        shownSeed = shown;
+        packSeed = pack;
+        if (!isPackSeed(shown)) {
+            rememberTried(shown);
+        }
+        DefaultComboBoxModel<Long> choices = new DefaultComboBoxModel<>();
+        pack.ifPresent(choices::addElement);
+        triedSeedsNewestFirst.forEach(choices::addElement);
+        showingSeeds = true;
+        try {
+            seeds.setModel(choices);
+            seeds.setSelectedItem(shown);
+        } finally {
+            showingSeeds = false;
+        }
+    }
+
+    private void rememberTried(long seed) {
+        triedSeedsNewestFirst.remove(seed);
+        triedSeedsNewestFirst.add(0, seed);
+        while (triedSeedsNewestFirst.size() > TRIED_SEEDS_KEPT) {
+            triedSeedsNewestFirst.remove(triedSeedsNewestFirst.size() - 1);
+        }
+    }
+
+    // A pick from the list arrives as a seed, anything typed as text.
+    private void chooseEnteredSeed() {
+        OptionalLong entered = parse(seeds.getSelectedItem());
+        if (entered.isEmpty()) {
+            UIManager.getLookAndFeel().provideErrorFeedback(seeds);
+            showSeed(shownSeed, packSeed);
+            return;
+        }
+        if (entered.getAsLong() != shownSeed) {
+            onSeedChosen.accept(entered.getAsLong());
+        }
+    }
+
+    private static OptionalLong parse(Object entered) {
+        if (entered instanceof Long seed) {
+            return OptionalLong.of(seed);
+        }
+        try {
+            return OptionalLong.of(Long.parseLong(String.valueOf(entered).trim()));
+        } catch (NumberFormatException notASeed) {
+            return OptionalLong.empty();
+        }
+    }
+
+    private void reroll() {
+        long seed;
+        do {
+            seed = ThreadLocalRandom.current().nextInt(RANDOM_SEED_BOUND);
+        } while (seed == shownSeed);
+        onSeedChosen.accept(seed);
+    }
+
+    private boolean isPackSeed(Object seed) {
+        return packSeed.isPresent() && seed instanceof Long value && value == packSeed.getAsLong();
+    }
+
+    private final class PackSeedMarker extends DefaultListCellRenderer {
+        private static final long serialVersionUID = -6061513307766393251L;
+
+        @Override
+        public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean selected, boolean focused) {
+            super.getListCellRendererComponent(list, value, index, selected, focused);
+            if (index >= 0 && isPackSeed(value)) {
+                setText(value + "  (pack)");
+            }
+            return this;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectSource.java

@@ -0,0 +1,52 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.engine.object.IrisObject;
+
+import java.util.List;
+import java.util.OptionalLong;
+
+/**
+ * Where an object explorer gets what it shows: the pack's object files, or the objects Iris generates from settings.
+ * Both are called on the explorer's loader thread only.
+ */
+interface ObjectSource {
+    /** What one entry is called, such as "object", for the browser's texts. */
+    String noun();
+
+    /** What the view shows when the pack has no entries. */
+    EmptyState emptyState();
+
+    /** The key of every entry, where a slash separates folders. */
+    List<String> keys(IrisData data);
+
+    /** The objects of the entry, one for an object file and one per variant for a procedural object; empty when none load. */
+    List<IrisObject> variants(IrisData data, String key);
+
+    /** The seed the pack bakes the entry's variants from; empty for anything not generated from a seed. */
+    default OptionalLong seed(String key) {
+        return OptionalLong.empty();
+    }
+
+    /** The entry's variants as {@code seed} would bake them; only asked of entries that have a seed. */
+    default List<IrisObject> variants(IrisData data, String key, long seed) {
+        throw new UnsupportedOperationException(key + " is not generated from a seed");
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectSummary.java

@@ -0,0 +1,65 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import org.bukkit.block.data.BlockData;
+
+import java.awt.image.BufferedImage;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+
+/**
+ * What an object is made of: its size and how many of each block type it uses, most used first.
+ */
+record ObjectSummary(String key, int sizeX, int sizeY, int sizeZ, int blockCount, List<BlockUse> blockUses) {
+    static ObjectSummary of(String key, ObjectMesh.Bounds bounds, Iterable<BlockData> blocks, Function<BlockData, BufferedImage> iconOf) {
+        Map<String, Integer> counts = new HashMap<>();
+        Map<String, BlockData> examples = new HashMap<>();
+        int blockCount = 0;
+        for (BlockData block : blocks) {
+            String blockType = block.getMaterial().getKey().getKey();
+            counts.merge(blockType, 1, Integer::sum);
+            examples.putIfAbsent(blockType, block);
+            blockCount++;
+        }
+        List<BlockUse> uses = counts.entrySet().stream()
+                .map(count -> new BlockUse(count.getKey(), count.getValue(), iconOf.apply(examples.get(count.getKey()))))
+                .sorted(Comparator.comparingInt(BlockUse::count).reversed().thenComparing(BlockUse::blockType))
+                .toList();
+        return new ObjectSummary(key, bounds.sizeX(), bounds.sizeY(), bounds.sizeZ(), blockCount, uses);
+    }
+
+    String name() {
+        return key.substring(key.lastIndexOf('/') + 1);
+    }
+
+    double filledFraction() {
+        long volume = (long) sizeX * sizeY * sizeZ;
+        return volume == 0 ? 0D : blockCount / (double) volume;
+    }
+
+    /**
+     * @param icon the block's texture, or null when Minecraft's textures are not available
+     */
+    record BlockUse(String blockType, int count, BufferedImage icon) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectVariantGallery.java

@@ -0,0 +1,358 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.volmit.iris.core.gui;
+
+import javax.swing.AbstractAction;
+import javax.swing.BorderFactory;
+import javax.swing.JComponent;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JScrollPane;
+import javax.swing.KeyStroke;
+import javax.swing.Scrollable;
+import javax.swing.Timer;
+import java.awt.AlphaComposite;
+import java.awt.BorderLayout;
+import java.awt.Cursor;
+import java.awt.Dimension;
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Rectangle;
+import java.awt.RenderingHints;
+import java.awt.event.ActionEvent;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.awt.geom.RoundRectangle2D;
+import java.awt.image.BufferedImage;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.IntConsumer;
+
+/**
+ * Every variant of a procedural object side by side, drawn at one scale so their sizes compare. Clicking one opens it
+ * in the 3D view. While new thumbnails are drawn, each card keeps its old one faded until its own arrives; cards
+ * still waiting after a moment play the loading animation, one after another like a wave.
+ */
+final class ObjectVariantGallery extends JPanel {
+    private static final long serialVersionUID = 6153024487310558262L;
+    private static final int THUMBNAIL_SIZE = 220;
+    private static final int CARD_PADDING = 6;
+    private static final int CARD_GAP = 12;
+    private static final int EDGE_MARGIN = 16;
+    // The variant bar floats over the bottom edge, so the last row scrolls clear of it.
+    private static final int VARIANT_BAR_CLEARANCE = 64;
+    private static final float OUTDATED_THUMBNAIL_OPACITY = 0.35F;
+    private static final int THUMBNAIL_SIZE_PER_LOADING_BLOCK = 14;
+    private static final int LOADING_WAVE_STEP_MILLIS = 90;
+
+    private final JLabel title = new JLabel(" ");
+    private final CardGrid grid = new CardGrid();
+    private final IntConsumer onVariantOpened;
+    private final Runnable onThemeChanged;
+    private final List<VariantCard> cards = new ArrayList<>();
+    private final Timer loadingTicker = new Timer(LoadingAnimation.FRAME_MILLIS, event -> repaintWaitingCards());
+    private int coveredLeftWidth;
+    private int selectedIndex;
+    private long waitingSinceMillis;
+
+    /**
+     * @param onVariantOpened told the index of a variant the user clicks
+     * @param onThemeChanged  told when the theme changes, since thumbnails are drawn on the theme's background
+     */
+    ObjectVariantGallery(IntConsumer onVariantOpened, Runnable onThemeChanged) {
+        super(new BorderLayout(0, StudioTheme.scale(EDGE_MARGIN)));
+        this.onVariantOpened = onVariantOpened;
+        this.onThemeChanged = onThemeChanged;
+        setOpaque(true);
+        setBackground(StudioTheme.EDITOR_BACKGROUND);
+        setFocusable(true);
+        title.setFont(StudioTheme.sectionFont());
+        title.setForeground(StudioTheme.TEXT);
+        JScrollPane scroll = StudioToolbar.scroll(grid);
+        scroll.setOpaque(false);
+        scroll.getViewport().setOpaque(false);
+        add(title, BorderLayout.NORTH);
+        add(scroll, BorderLayout.CENTER);
+        keepClearOfOverlays();
+    }
+
+    @Override
+    public void updateUI() {
+        super.updateUI();
+        if (onThemeChanged != null) {
+            onThemeChanged.run();
+        }
+    }
+
+    void bindKey(int keyCode, String name, Runnable action) {
+        getInputMap(WHEN_ANCESTOR_OF_FOCUSED_COMPONENT).put(KeyStroke.getKeyStroke(keyCode, 0), name);
+        getActionMap().put(name, new AbstractAction() {
+            @Override
+            public void actionPerformed(ActionEvent event) {
+                action.run();
+            }
+        });
+    }
+
+    void setCoveredLeftWidth(int width) {
+        coveredLeftWidth = width;
+        keepClearOfOverlays();
+        revalidate();
+    }
+
+    int thumbnailSize() {
+        return StudioTheme.scale(THUMBNAIL_SIZE);
+    }
+
+    /**
+     * Cards for {@code count} variants, waiting for their thumbnails. The cards already shown stay, with their old
+     * thumbnails faded, so a reroll never blanks the view.
+     */
+    void showVariants(String heading, int count, int selected) {
+        title.setText(heading);
+        if (count != cards.size()) {
+            replaceCards(count);
+        }
+        startWaiting();
+        select(selected);
+    }
+
+    /** Fades every thumbnail while something new loads. */
+    void showLoading() {
+        startWaiting();
+    }
+
+    void showThumbnail(int index, BufferedImage thumbnail) {
+        if (index < cards.size()) {
+            cards.get(index).showThumbnail(thumbnail);
+        }
+        if (cards.stream().noneMatch(VariantCard::isWaiting)) {
+            loadingTicker.stop();
+        }
+    }
+
+    private void replaceCards(int count) {
+        cards.clear();
+        grid.removeAll();
+        for (int index = 0; index < count; index++) {
+            VariantCard card = new VariantCard(index);
+            cards.add(card);
+            grid.add(card);
+        }
+        grid.revalidate();
+        grid.repaint();
+    }
+
+    private void startWaiting() {
+        if (!loadingTicker.isRunning()) {
+            waitingSinceMillis = System.currentTimeMillis();
+            loadingTicker.start();
+        }
+        cards.forEach(VariantCard::markOutdated);
+    }
+
+    private void repaintWaitingCards() {
+        if (LoadingAnimation.isDue(waitingSinceMillis)) {
+            cards.stream().filter(VariantCard::isWaiting).forEach(VariantCard::repaint);
+        }
+    }
+
+    void select(int index) {
+        selectedIndex = index;
+        cards.forEach(VariantCard::repaint);
+        if (index < cards.size()) {
+            VariantCard card = cards.get(index);
+            grid.scrollRectToVisible(card.getBounds());
+        }
+    }
+
+    void showMessage(String text) {
+        title.setText(text);
+        loadingTicker.stop();
+        cards.clear();
+        grid.removeAll();
+        grid.revalidate();
+        grid.repaint();
+    }
+
+    private void keepClearOfOverlays() {
+        int margin = StudioTheme.scale(EDGE_MARGIN);
+        setBorder(BorderFactory.createEmptyBorder(margin, coveredLeftWidth + margin, StudioTheme.scale(VARIANT_BAR_CLEARANCE), margin));
+    }
+
+    /**
+     * Cards in as many columns as fit the width, wrapping onto more rows.
+     */
+    private final class CardGrid extends JPanel implements Scrollable {
+        private static final long serialVersionUID = -3618705187215931408L;
+
+        CardGrid() {
+            super(null);
+            setOpaque(false);
+        }
+
+        @Override
+        public void doLayout() {
+            Dimension card = cardSize();
+            int gap = StudioTheme.scale(CARD_GAP);
+            int columns = columns();
+            for (int index = 0; index < getComponentCount(); index++) {
+                int column = index % columns;
+                int row = index / columns;
+                getComponent(index).setBounds(column * (card.width + gap), row * (card.height + gap), card.width, card.height);
+            }
+        }
+
+        @Override
+        public Dimension getPreferredSize() {
+            Dimension card = cardSize();
+            int gap = StudioTheme.scale(CARD_GAP);
+            int rows = (getComponentCount() + columns() - 1) / columns();
+            return new Dimension(card.width, Math.max(0, rows * (card.height + gap) - gap));
+        }
+
+        private int columns() {
+            int gap = StudioTheme.scale(CARD_GAP);
+            return Math.max(1, (getWidth() + gap) / (cardSize().width + gap));
+        }
+
+        @Override
+        public Dimension getPreferredScrollableViewportSize() {
+            return getPreferredSize();
+        }
+
+        @Override
+        public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
+            return cardSize().height / 4;
+        }
+
+        @Override
+        public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
+            return visibleRect.height;
+        }
+
+        @Override
+        public boolean getScrollableTracksViewportWidth() {
+            return true;
+        }
+
+        @Override
+        public boolean getScrollableTracksViewportHeight() {
+            return false;
+        }
+    }
+
+    private Dimension cardSize() {
+        int padding = StudioTheme.scale(CARD_PADDING);
+        int labelHeight = getFontMetrics(StudioTheme.smallFont()).getHeight();
+        return new Dimension(thumbnailSize() + 2 * padding, thumbnailSize() + labelHeight + 3 * padding);
+    }
+
+    private final class VariantCard extends JComponent {
+        private static final long serialVersionUID = 2296135546207834180L;
+
+        private final int index;
+        private BufferedImage thumbnail;
+        private boolean thumbnailOutdated;
+        private boolean hovered;
+
+        VariantCard(int index) {
+            this.index = index;
+            setToolTipText("Open variant " + (index + 1) + " in 3D");
+            setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
+            addMouseListener(new MouseAdapter() {
+                @Override
+                public void mouseClicked(MouseEvent event) {
+                    onVariantOpened.accept(VariantCard.this.index);
+                }
+
+                @Override
+                public void mouseEntered(MouseEvent event) {
+                    setHovered(true);
+                }
+
+                @Override
+                public void mouseExited(MouseEvent event) {
+                    setHovered(false);
+                }
+            });
+        }
+
+        void showThumbnail(BufferedImage image) {
+            thumbnail = image;
+            thumbnailOutdated = false;
+            repaint();
+        }
+
+        void markOutdated() {
+            thumbnailOutdated = true;
+            repaint();
+        }
+
+        boolean isWaiting() {
+            return thumbnail == null || thumbnailOutdated;
+        }
+
+        private void setHovered(boolean nowHovered) {
+            hovered = nowHovered;
+            repaint();
+        }
+
+        @Override
+        protected void paintComponent(Graphics graphics) {
+            Graphics2D canvas = (Graphics2D) graphics.create();
+            try {
+                canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+                canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+                double arc = StudioTheme.scale(StudioTheme.OVERLAY_ARC);
+                canvas.setColor(index == selectedIndex ? StudioTheme.SELECTION : hovered ? StudioTheme.HOVER_BACKGROUND : StudioTheme.PANEL_BACKGROUND);
+                canvas.fill(new RoundRectangle2D.Double(0, 0, getWidth(), getHeight(), arc, arc));
+                int padding = StudioTheme.scale(CARD_PADDING);
+                int size = thumbnailSize();
+                canvas.setFont(StudioTheme.smallFont());
+                FontMetrics metrics = canvas.getFontMetrics();
+                drawThumbnail(canvas, padding, size);
+                canvas.setColor(StudioTheme.TEXT);
+                drawCentered(canvas, "Variant " + (index + 1), padding * 2 + size + metrics.getAscent());
+            } finally {
+                canvas.dispose();
+            }
+        }
+
+        private void drawThumbnail(Graphics2D canvas, int padding, int size) {
+            if (thumbnail != null) {
+                Graphics2D faded = (Graphics2D) canvas.create();
+                if (thumbnailOutdated) {
+                    faded.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, OUTDATED_THUMBNAIL_OPACITY));
+                }
+                faded.drawImage(thumbnail, padding, padding, size, size, null);
+                faded.dispose();
+            }
+            if (isWaiting() && LoadingAnimation.isDue(waitingSinceMillis)) {
+                long shownMillis = System.currentTimeMillis() - waitingSinceMillis - LoadingAnimation.SHOW_AFTER_MILLIS;
+                LoadingAnimation.paint(canvas, padding + size / 2D, padding + size / 2D, size / (double) THUMBNAIL_SIZE_PER_LOADING_BLOCK,
+                        shownMillis - (long) index * LOADING_WAVE_STEP_MILLIS);
+            }
+        }
+
+        private void drawCentered(Graphics2D canvas, String text, int baseline) {
+            canvas.drawString(text, (getWidth() - canvas.getFontMetrics().stringWidth(text)) / 2, baseline);
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectVariantPicker.java

@@ -0,0 +1,201 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.volmit.iris.core.gui;
+
+import javax.swing.Box;
+import javax.swing.BoxLayout;
+import javax.swing.JButton;
+import javax.swing.JComponent;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.SwingConstants;
+import java.awt.BorderLayout;
+import java.awt.Dimension;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.awt.geom.RoundRectangle2D;
+import java.util.OptionalLong;
+import java.util.function.IntConsumer;
+import java.util.function.LongConsumer;
+
+/**
+ * A small bar floating at the bottom of the object view that steps through the variants of a procedural object and
+ * the seeds they are baked from, and switches between one variant in 3D and all of them side by side. It hides itself
+ * for anything with a single variant and no seed.
+ */
+final class ObjectVariantPicker extends JPanel {
+    private static final long serialVersionUID = -2716301839488217455L;
+    private static final int BOTTOM_MARGIN = 14;
+    private static final int VARIANT_LABEL_WIDTH = 110;
+    private static final int SECTION_GAP = 10;
+    private static final String VARIANT_SHORTCUT_HINT = " · [ and ]";
+    private static final String COMPARE_SHORTCUT_HINT = " · G";
+
+    private final JLabel shownVariant = label(VARIANT_LABEL_WIDTH);
+    private final JComponent variantStepper;
+    private final ObjectSeedChooser seedChooser;
+    private final JButton compareButton;
+    private final IntConsumer onVariantChosen;
+    private int variantCount;
+    private int shownIndex;
+    private boolean seeded;
+    private int coveredLeftWidth;
+
+    /**
+     * @param onVariantChosen told the index of the variant to show whenever the user steps to another one
+     * @param onSeedChosen    told the seed to bake the variants from whenever the user chooses another one
+     * @param onCompareToggled told when the user switches between one variant and all of them
+     */
+    ObjectVariantPicker(IntConsumer onVariantChosen, LongConsumer onSeedChosen, Runnable onCompareToggled) {
+        this.onVariantChosen = onVariantChosen;
+        setLayout(new BoxLayout(this, BoxLayout.X_AXIS));
+        setOpaque(false);
+        setBorder(StudioTheme.emptyBorder(3, 4, 3, 4));
+        variantStepper = stepper(shownVariant,
+                StudioToolbar.button("‹", "Previous variant" + VARIANT_SHORTCUT_HINT, () -> stepBy(-1)),
+                StudioToolbar.button("›", "Next variant" + VARIANT_SHORTCUT_HINT, () -> stepBy(1)));
+        seedChooser = new ObjectSeedChooser(onSeedChosen);
+        compareButton = StudioToolbar.button("", "", onCompareToggled);
+        add(variantStepper);
+        add(Box.createHorizontalStrut(StudioTheme.scale(SECTION_GAP)));
+        add(seedChooser);
+        add(Box.createHorizontalStrut(StudioTheme.scale(SECTION_GAP)));
+        add(compareButton);
+        showComparing(false);
+        showVariants(0, 0);
+    }
+
+    private static JLabel label(int width) {
+        JLabel label = new JLabel(" ", SwingConstants.CENTER);
+        label.setFont(StudioTheme.smallFont());
+        label.setForeground(StudioTheme.TEXT);
+        label.setPreferredSize(new Dimension(StudioTheme.scale(width), label.getPreferredSize().height));
+        return label;
+    }
+
+    private static JComponent stepper(JLabel shown, JButton previous, JButton next) {
+        JPanel stepper = new JPanel(new BorderLayout());
+        stepper.setOpaque(false);
+        stepper.add(previous, BorderLayout.WEST);
+        stepper.add(shown, BorderLayout.CENTER);
+        stepper.add(next, BorderLayout.EAST);
+        return stepper;
+    }
+
+    /**
+     * The view with this bar floating over its bottom edge, centred on the part the left island leaves uncovered.
+     */
+    JComponent floatingOver(JComponent view) {
+        ObjectVariantPicker picker = this;
+        JPanel stack = new JPanel(null) {
+            private static final long serialVersionUID = 1609842937565014832L;
+
+            // The bar overlaps the view, so the view may not repaint without the bar on top of it.
+            @Override
+            public boolean isOptimizedDrawingEnabled() {
+                return false;
+            }
+
+            @Override
+            public void doLayout() {
+                view.setBounds(0, 0, getWidth(), getHeight());
+                Dimension size = picker.getPreferredSize();
+                int centerX = coveredLeftWidth + (getWidth() - coveredLeftWidth) / 2;
+                picker.setBounds(centerX - size.width / 2, getHeight() - size.height - StudioTheme.scale(BOTTOM_MARGIN), size.width, size.height);
+            }
+        };
+        stack.add(picker);
+        stack.add(view);
+        return stack;
+    }
+
+    void setCoveredLeftWidth(int width) {
+        coveredLeftWidth = width;
+        relayout();
+    }
+
+    /**
+     * Shows variant {@code index} of {@code count} without telling anyone, since the caller already shows it.
+     */
+    void showVariants(int count, int index) {
+        variantCount = count;
+        shownIndex = index;
+        shownVariant.setText("Variant " + (index + 1) + " of " + count);
+        variantStepper.setVisible(count > 1);
+        compareButton.setVisible(count > 1);
+        showWhenUseful();
+    }
+
+    /**
+     * Shows the seed the variants are baked from; empty for objects not generated from a seed.
+     */
+    void showSeed(OptionalLong shown, OptionalLong pack) {
+        seeded = shown.isPresent();
+        seedChooser.setVisible(seeded);
+        shown.ifPresent(seed -> seedChooser.showSeed(seed, pack));
+        showWhenUseful();
+    }
+
+    void forgetTriedSeeds() {
+        seedChooser.forgetTriedSeeds();
+    }
+
+    void showComparing(boolean comparing) {
+        compareButton.setText(comparing ? "3D view" : "All variants");
+        compareButton.setToolTipText((comparing ? "Show the chosen variant in 3D" : "Show every variant side by side") + COMPARE_SHORTCUT_HINT);
+        relayout();
+    }
+
+    void stepBy(int step) {
+        if (variantCount < 2) {
+            return;
+        }
+        shownIndex = Math.floorMod(shownIndex + step, variantCount);
+        showVariants(variantCount, shownIndex);
+        onVariantChosen.accept(shownIndex);
+    }
+
+    private void showWhenUseful() {
+        setVisible(variantCount > 1 || seeded);
+        relayout();
+    }
+
+    private void relayout() {
+        if (getParent() != null) {
+            getParent().revalidate();
+            getParent().repaint();
+        }
+    }
+
+    @Override
+    protected void paintComponent(Graphics graphics) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+            double arc = StudioTheme.scale(StudioTheme.OVERLAY_ARC);
+            RoundRectangle2D shape = new RoundRectangle2D.Double(0.5, 0.5, getWidth() - 1D, getHeight() - 1D, arc, arc);
+            canvas.setColor(StudioTheme.OVERLAY_BACKGROUND);
+            canvas.fill(shape);
+            canvas.setColor(StudioTheme.OVERLAY_BORDER);
+            canvas.draw(shape);
+        } finally {
+            canvas.dispose();
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ObjectViewport.java

@@ -0,0 +1,328 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.AbstractAction;
+import javax.swing.JComponent;
+import javax.swing.KeyStroke;
+import javax.swing.SwingUtilities;
+import javax.swing.Timer;
+import java.awt.AlphaComposite;
+import java.awt.EventQueue;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Point;
+import java.awt.RenderingHints;
+import java.awt.event.ActionEvent;
+import java.awt.event.ComponentAdapter;
+import java.awt.event.ComponentEvent;
+import java.awt.event.KeyEvent;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseWheelEvent;
+import java.awt.image.BufferedImage;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.function.UnaryOperator;
+
+/**
+ * The 3D view of one object. Drag to orbit, shift-drag or middle-drag to pan, scroll to zoom; arrow keys orbit and
+ * plus and minus zoom too. Frames are drawn on a background thread, one at a time, always for the latest camera.
+ * While the next object loads, the last picture stays up; only a slow load dims it under the loading animation.
+ */
+final class ObjectViewport extends JComponent {
+    private static final long serialVersionUID = -3175226517409913524L;
+    private static final double WHEEL_ZOOM_EXPONENT = 0.12D;
+    private static final double KEY_ZOOM_FACTOR = 1.1D;
+    private static final int KEY_ORBIT_PIXELS = 12;
+    private static final float LOADING_DIM_OPACITY = 0.88F;
+    private static final double LOADING_BLOCK_SIZE = 16D;
+    private static final int LOADING_TEXT_GAP = 46;
+
+    private final ExecutorService renderThread = Executors.newSingleThreadExecutor(runnable -> {
+        Thread thread = new Thread(runnable, "Iris Object Viewer");
+        thread.setDaemon(true);
+        return thread;
+    });
+    private ObjectMesh mesh;
+    private ObjectCamera camera = ObjectCamera.START;
+    private BufferedImage frame;
+    private String message = "Choose an object";
+    private EmptyState emptyState;
+    private boolean rendering;
+    private boolean renderAgain;
+    private Point dragPoint;
+    private int coveredLeftWidth;
+    private final Timer loadingTicker = new Timer(LoadingAnimation.FRAME_MILLIS, event -> repaint());
+    private String loadingText;
+    private long loadingSinceMillis;
+
+    ObjectViewport() {
+        setOpaque(true);
+        setBackground(StudioTheme.EDITOR_BACKGROUND);
+        setFocusable(true);
+        installMouseControls();
+        installKeyControls();
+        addComponentListener(new ComponentAdapter() {
+            @Override
+            public void componentResized(ComponentEvent event) {
+                requestFrame();
+            }
+        });
+    }
+
+    // The theme changed, and the last frame was drawn on the old theme's background.
+    @Override
+    public void updateUI() {
+        super.updateUI();
+        requestFrame();
+    }
+
+    // The last picture stays up until the first one of this mesh is drawn.
+    void show(ObjectMesh nextMesh) {
+        mesh = nextMesh;
+        camera = ObjectCamera.START;
+        message = nextMesh.isEmpty() ? "No visible blocks" : null;
+        emptyState = null;
+        if (nextMesh.isEmpty()) {
+            frame = null;
+            finishLoading();
+        }
+        requestFrame();
+        repaint();
+    }
+
+    /**
+     * Marks the view as loading something new. A load already under way keeps its start, so stepping quickly through
+     * objects still shows the animation once the wait adds up.
+     */
+    void showLoading(String text) {
+        if (loadingText == null) {
+            loadingSinceMillis = System.currentTimeMillis();
+        }
+        loadingText = text;
+        message = null;
+        emptyState = null;
+        loadingTicker.start();
+    }
+
+    private void finishLoading() {
+        loadingText = null;
+        loadingTicker.stop();
+    }
+
+    /**
+     * Swaps in another mesh of the same object, like one with its top layers cut away, keeping the camera.
+     */
+    void replaceMesh(ObjectMesh nextMesh) {
+        mesh = nextMesh;
+        message = nextMesh.isEmpty() ? "No visible blocks" : null;
+        emptyState = null;
+        requestFrame();
+        repaint();
+    }
+
+    void bindKey(int keyCode, String name, Runnable action) {
+        getInputMap(WHEN_FOCUSED).put(KeyStroke.getKeyStroke(keyCode, 0), name);
+        getActionMap().put(name, new AbstractAction() {
+            @Override
+            public void actionPerformed(ActionEvent event) {
+                action.run();
+            }
+        });
+    }
+
+    void showMessage(String text) {
+        mesh = null;
+        message = text;
+        emptyState = null;
+        frame = null;
+        finishLoading();
+        repaint();
+    }
+
+    void showEmptyState(EmptyState state) {
+        mesh = null;
+        message = null;
+        emptyState = state;
+        frame = null;
+        finishLoading();
+        repaint();
+    }
+
+    /**
+     * Keeps the object clear of a panel floating over the viewport's left side.
+     */
+    void setCoveredLeftWidth(int width) {
+        if (width == coveredLeftWidth) {
+            return;
+        }
+        coveredLeftWidth = width;
+        requestFrame();
+    }
+
+    void resetCamera() {
+        moveCamera(current -> ObjectCamera.START);
+    }
+
+    void close() {
+        loadingTicker.stop();
+        renderThread.shutdownNow();
+    }
+
+    private void moveCamera(UnaryOperator<ObjectCamera> move) {
+        camera = move.apply(camera);
+        requestFrame();
+    }
+
+    private void requestFrame() {
+        if (mesh == null || mesh.isEmpty() || getWidth() < 1 || getHeight() < 1) {
+            return;
+        }
+        if (rendering) {
+            renderAgain = true;
+            return;
+        }
+        rendering = true;
+        ObjectMesh frameMesh = mesh;
+        ObjectCamera frameCamera = camera;
+        int width = getWidth();
+        int height = getHeight();
+        int covered = coveredLeftWidth;
+        renderThread.execute(() -> {
+            BufferedImage image = ObjectRenderer.render(frameMesh, frameCamera, width, height, covered);
+            EventQueue.invokeLater(() -> finishFrame(frameMesh, image));
+        });
+    }
+
+    private void finishFrame(ObjectMesh frameMesh, BufferedImage image) {
+        rendering = false;
+        if (frameMesh == mesh) {
+            frame = image;
+            finishLoading();
+            repaint();
+        }
+        if (renderAgain) {
+            renderAgain = false;
+            requestFrame();
+        }
+    }
+
+    @Override
+    protected void paintComponent(Graphics graphics) {
+        graphics.setColor(getBackground());
+        graphics.fillRect(0, 0, getWidth(), getHeight());
+        if (frame != null) {
+            graphics.drawImage(frame, 0, 0, null);
+        }
+        if (loadingText != null && LoadingAnimation.isDue(loadingSinceMillis)) {
+            drawLoading((Graphics2D) graphics);
+        }
+        if (message != null) {
+            drawMessage((Graphics2D) graphics);
+        }
+        if (emptyState != null) {
+            emptyState.paint((Graphics2D) graphics, this, coveredLeftWidth + (getWidth() - coveredLeftWidth) / 2, getHeight() / 2);
+        }
+    }
+
+    private void drawLoading(Graphics2D graphics) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            if (frame != null) {
+                canvas.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, LOADING_DIM_OPACITY));
+                canvas.setColor(getBackground());
+                canvas.fillRect(0, 0, getWidth(), getHeight());
+                canvas.setComposite(AlphaComposite.SrcOver);
+            }
+            int centerX = coveredLeftWidth + (getWidth() - coveredLeftWidth) / 2;
+            int centerY = getHeight() / 2;
+            long shownMillis = System.currentTimeMillis() - loadingSinceMillis - LoadingAnimation.SHOW_AFTER_MILLIS;
+            LoadingAnimation.paint(canvas, centerX, centerY, StudioTheme.scale(LOADING_BLOCK_SIZE), shownMillis);
+            canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+            canvas.setFont(StudioTheme.font());
+            canvas.setColor(StudioTheme.MUTED_TEXT);
+            String text = loadingText + "...";
+            int textWidth = canvas.getFontMetrics().stringWidth(text);
+            canvas.drawString(text, centerX - textWidth / 2, centerY + StudioTheme.scale(LOADING_TEXT_GAP));
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private void drawMessage(Graphics2D canvas) {
+        canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+        canvas.setFont(StudioTheme.font());
+        canvas.setColor(StudioTheme.MUTED_TEXT);
+        int textWidth = canvas.getFontMetrics().stringWidth(message);
+        canvas.drawString(message, (getWidth() - textWidth) / 2, getHeight() / 2);
+    }
+
+    private void installMouseControls() {
+        MouseAdapter mouse = new MouseAdapter() {
+            @Override
+            public void mousePressed(MouseEvent event) {
+                dragPoint = event.getPoint();
+                requestFocusInWindow();
+            }
+
+            @Override
+            public void mouseReleased(MouseEvent event) {
+                dragPoint = null;
+            }
+
+            @Override
+            public void mouseDragged(MouseEvent event) {
+                if (dragPoint == null) {
+                    return;
+                }
+                int draggedX = event.getX() - dragPoint.x;
+                int draggedY = event.getY() - dragPoint.y;
+                dragPoint = event.getPoint();
+                boolean panning = event.isShiftDown() || SwingUtilities.isMiddleMouseButton(event);
+                moveCamera(current -> panning
+                        ? current.pannedBy(2D * draggedX / Math.max(1, getWidth() - coveredLeftWidth), -2D * draggedY / getHeight())
+                        : current.orbitedBy(draggedX, draggedY));
+            }
+
+            @Override
+            public void mouseWheelMoved(MouseWheelEvent event) {
+                moveCamera(current -> current.zoomedBy(Math.exp(-event.getPreciseWheelRotation() * WHEEL_ZOOM_EXPONENT)));
+            }
+        };
+        addMouseListener(mouse);
+        addMouseMotionListener(mouse);
+        addMouseWheelListener(mouse);
+    }
+
+    private void installKeyControls() {
+        bindKey(KeyEvent.VK_LEFT, "orbit-left", current -> current.orbitedBy(-KEY_ORBIT_PIXELS, 0));
+        bindKey(KeyEvent.VK_RIGHT, "orbit-right", current -> current.orbitedBy(KEY_ORBIT_PIXELS, 0));
+        bindKey(KeyEvent.VK_UP, "orbit-up", current -> current.orbitedBy(0, KEY_ORBIT_PIXELS));
+        bindKey(KeyEvent.VK_DOWN, "orbit-down", current -> current.orbitedBy(0, -KEY_ORBIT_PIXELS));
+        bindKey(KeyEvent.VK_EQUALS, "zoom-in", current -> current.zoomedBy(KEY_ZOOM_FACTOR));
+        bindKey(KeyEvent.VK_ADD, "zoom-in-keypad", current -> current.zoomedBy(KEY_ZOOM_FACTOR));
+        bindKey(KeyEvent.VK_MINUS, "zoom-out", current -> current.zoomedBy(1D / KEY_ZOOM_FACTOR));
+        bindKey(KeyEvent.VK_SUBTRACT, "zoom-out-keypad", current -> current.zoomedBy(1D / KEY_ZOOM_FACTOR));
+    }
+
+    private void bindKey(int keyCode, String name, UnaryOperator<ObjectCamera> move) {
+        bindKey(keyCode, name, () -> moveCamera(move));
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PackObjectSource.java

@@ -0,0 +1,53 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.engine.object.IrisObject;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * The pack's object files, by their load keys.
+ */
+final class PackObjectSource implements ObjectSource {
+    private static final int EMPTY_ICON_SIZE = 40;
+
+    @Override
+    public String noun() {
+        return "object";
+    }
+
+    @Override
+    public EmptyState emptyState() {
+        return new EmptyState(MapViewIcon.large(MapView.OBJECTS, EMPTY_ICON_SIZE), "No objects yet",
+                "Put the pack's .iob objects in", "objects/", "They appear here once the pack reloads.");
+    }
+
+    @Override
+    public List<String> keys(IrisData data) {
+        return Arrays.asList(data.getObjectLoader().getPossibleKeys());
+    }
+
+    @Override
+    public List<IrisObject> variants(IrisData data, String key) {
+        IrisObject object = data.getObjectLoader().load(key);
+        return object == null ? List.of() : List.of(object);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PaletteCatalog.java

@@ -0,0 +1,263 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.google.gson.stream.JsonReader;
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisBlockData;
+import com.volmit.iris.engine.object.IrisRegion;
+import com.volmit.iris.util.collection.KList;
+
+import java.io.File;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+
+record PaletteCatalog(List<RegionEntry> regions, List<String> biomesOutsideRegions, Map<String, BiomeEntry> biomes,
+                      List<SnippetEntry> snippets) {
+    private static final int SUMMARIZED_BLOCK_COUNT = 3;
+
+    static PaletteCatalog load(Engine engine) {
+        IrisData data = engine.getData();
+        Map<String, BiomeEntry> biomes = loadBiomes(data);
+        List<RegionEntry> regions = new ArrayList<>();
+        Set<String> biomesInRegions = new HashSet<>();
+        for (String regionKey : regionKeysInUse(engine)) {
+            IrisRegion region = data.getRegionLoader().load(regionKey);
+            if (region == null) {
+                continue;
+            }
+            RegionEntry entry = describeRegion(regionKey, region, biomes);
+            regions.add(entry);
+            entry.groups().forEach(group -> group.biomeKeys().forEach(key -> collectWithChildren(key, biomes, biomesInRegions)));
+        }
+        List<String> outside = biomes.keySet().stream().filter(key -> !biomesInRegions.contains(key)).toList();
+        return new PaletteCatalog(List.copyOf(regions), outside, Map.copyOf(biomes), loadSnippets(data, biomes));
+    }
+
+    // Snippet files no biome refers to are listed too, so a new snippet shows up before it is put to use.
+    private static List<SnippetEntry> loadSnippets(IrisData data, Map<String, BiomeEntry> biomes) {
+        Map<String, SnippetEntry> snippets = new LinkedHashMap<>();
+        for (BiomeEntry biome : biomes.values()) {
+            for (PaletteSummary summary : biome.palettes()) {
+                if (summary.snippet() == null) {
+                    continue;
+                }
+                BiomePalette.SnippetFolder folder = summary.palette().kind().snippetFolder();
+                snippets.computeIfAbsent(folder.folder() + "/" + summary.snippet(),
+                                key -> new SnippetEntry(folder, summary.snippet(), summary.blocks(), new ArrayList<>()))
+                        .uses().add(summary.palette());
+            }
+        }
+        for (BiomePalette.SnippetFolder folder : BiomePalette.SnippetFolder.values()) {
+            for (String reference : data.getPossibleSnippets(folder.folder())) {
+                String path = folder.pathOf(reference);
+                snippets.putIfAbsent(folder.folder() + "/" + path, new SnippetEntry(folder, path, null, List.of()));
+            }
+        }
+        return snippets.values().stream()
+                .map(snippet -> new SnippetEntry(snippet.folder(), snippet.path(), snippet.blocks(), List.copyOf(snippet.uses())))
+                .sorted(Comparator.comparing(SnippetEntry::folder).thenComparing(SnippetEntry::path))
+                .toList();
+    }
+
+    // A studio focus region is generated even when the dimension's region list doesn't include it.
+    private static Set<String> regionKeysInUse(Engine engine) {
+        Set<String> keys = new LinkedHashSet<>();
+        if (engine.getDimension().hasFocusRegion()) {
+            keys.add(engine.getDimension().getFocusRegion());
+        }
+        keys.addAll(engine.getDimension().getRegions());
+        return keys;
+    }
+
+    BiomeEntry biome(String key) {
+        return key == null ? null : biomes.get(key);
+    }
+
+    RegionEntry region(String key) {
+        return regions.stream().filter(region -> region.key().equals(key)).findFirst().orElse(null);
+    }
+
+    static String summarizeBlocks(KList<IrisBlockData> blocks) {
+        List<String> names = blocks.stream()
+                .map(block -> block.getBlock().replace("minecraft:", "").toLowerCase(Locale.ROOT))
+                .distinct()
+                .toList();
+        if (names.size() <= SUMMARIZED_BLOCK_COUNT) {
+            return String.join(", ", names);
+        }
+        return String.join(", ", names.subList(0, SUMMARIZED_BLOCK_COUNT))
+                + " +" + (names.size() - SUMMARIZED_BLOCK_COUNT) + " more";
+    }
+
+    private static Map<String, BiomeEntry> loadBiomes(IrisData data) {
+        String[] keys = data.getBiomeLoader().getPossibleKeys();
+        Map<String, IrisBiome> loaded = new LinkedHashMap<>();
+        if (keys == null) {
+            return Map.of();
+        }
+        Arrays.sort(keys);
+        for (String key : keys) {
+            IrisBiome biome = data.getBiomeLoader().load(key);
+            if (biome != null) {
+                loaded.put(key, biome);
+            }
+        }
+        Map<String, List<String>> parentsByChild = parentsByChild(loaded);
+        Map<String, BiomeEntry> biomes = new LinkedHashMap<>();
+        loaded.forEach((key, biome) -> biomes.put(key, new BiomeEntry(
+                key,
+                biome.getName(),
+                summarizePalettes(key, biome),
+                biome.getChildren().stream().filter(loaded::containsKey).distinct().toList(),
+                parentsByChild.getOrDefault(key, List.of())
+        )));
+        return biomes;
+    }
+
+    private static Map<String, List<String>> parentsByChild(Map<String, IrisBiome> biomes) {
+        Map<String, List<String>> parents = new LinkedHashMap<>();
+        biomes.forEach((parentKey, parent) -> parent.getChildren().stream().distinct().forEach(childKey ->
+                parents.computeIfAbsent(childKey, key -> new ArrayList<>()).add(parentKey)));
+        return parents;
+    }
+
+    static List<PaletteSummary> summarizePalettes(String key, IrisBiome biome) {
+        JsonObject biomeSource = readSource(biome.getLoadFile());
+        return BiomePalette.allOf(key, biome).stream()
+                .map(palette -> new PaletteSummary(palette, snippetName(biomeSource, palette),
+                        summarizeBlocks(palette.blocksIn(biome))))
+                .toList();
+    }
+
+    // Snippets are copied into the biome when it loads, so only its file still tells which palettes came from one.
+    private static String snippetName(JsonObject biomeSource, BiomePalette palette) {
+        JsonElement element = biomeSource == null ? null : biomeSource.get(palette.kind().jsonKey());
+        if (element instanceof JsonArray list) {
+            element = palette.index() < list.size() ? list.get(palette.index()) : null;
+        }
+        if (element == null || !element.isJsonPrimitive()) {
+            return null;
+        }
+        return palette.kind().snippetFolder().pathOf(element.getAsString());
+    }
+
+    private static JsonObject readSource(File file) {
+        if (file == null || !file.isFile()) {
+            return null;
+        }
+        try (JsonReader reader = new JsonReader(new FileReader(file))) {
+            reader.setLenient(true);
+            JsonElement source = JsonParser.parseReader(reader);
+            return source.isJsonObject() ? source.getAsJsonObject() : null;
+        } catch (IOException | RuntimeException e) {
+            return null;
+        }
+    }
+
+    private static RegionEntry describeRegion(String key, IrisRegion region, Map<String, BiomeEntry> biomes) {
+        List<BiomeGroup> groups = new ArrayList<>();
+        addGroup(groups, "Land", region.getLandBiomes(), biomes);
+        addGroup(groups, "Shore", region.getShoreBiomes(), biomes);
+        addGroup(groups, "Sea", region.getSeaBiomes(), biomes);
+        addGroup(groups, "Cave", region.getCaveBiomes(), biomes);
+        return new RegionEntry(key, region.getName(), List.copyOf(groups));
+    }
+
+    private static void addGroup(List<BiomeGroup> groups, String label, List<String> keys, Map<String, BiomeEntry> biomes) {
+        List<String> known = keys.stream().filter(biomes::containsKey).distinct().toList();
+        if (!known.isEmpty()) {
+            groups.add(new BiomeGroup(label, known));
+        }
+    }
+
+    private static void collectWithChildren(String key, Map<String, BiomeEntry> biomes, Set<String> collected) {
+        BiomeEntry biome = biomes.get(key);
+        if (biome == null || !collected.add(key)) {
+            return;
+        }
+        biome.childKeys().forEach(child -> collectWithChildren(child, biomes, collected));
+    }
+
+    record RegionEntry(String key, String name, List<BiomeGroup> groups) {
+        List<String> allBiomeKeys() {
+            return groups.stream().flatMap(group -> group.biomeKeys().stream()).distinct().toList();
+        }
+    }
+
+    record BiomeGroup(String label, List<String> biomeKeys) {
+    }
+
+    /**
+     * @param parentKeys the biomes that list this one as a child, which it can appear inside of
+     */
+    record BiomeEntry(String key, String name, List<PaletteSummary> palettes, List<String> childKeys,
+                      List<String> parentKeys) {
+        boolean matches(String filter) {
+            if (key.toLowerCase().contains(filter) || name.toLowerCase().contains(filter)) {
+                return true;
+            }
+            return palettes.stream().anyMatch(summary -> summary.text().toLowerCase().contains(filter));
+        }
+
+        BiomePalette firstPalette() {
+            return palettes.isEmpty() ? null : palettes.get(0).palette();
+        }
+    }
+
+    /**
+     * A snippet file palettes can come from.
+     *
+     * @param blocks a summary of its blocks, or null when no biome uses it
+     * @param uses   the palettes made from it, in biome order
+     */
+    record SnippetEntry(BiomePalette.SnippetFolder folder, String path, String blocks, List<BiomePalette> uses) {
+        boolean matches(String filter) {
+            return path.toLowerCase(Locale.ROOT).contains(filter)
+                    || (blocks != null && blocks.toLowerCase(Locale.ROOT).contains(filter));
+        }
+    }
+
+    /**
+     * @param snippet the path of the snippet file the palette comes from, or null when the biome defines it itself
+     */
+    record PaletteSummary(BiomePalette palette, String snippet, String blocks) {
+        String text() {
+            return snippet == null
+                    ? palette.label() + " · " + blocks
+                    : palette.label() + " · " + snippet + " snippet · " + blocks;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PaletteExplorerStart.java

@@ -0,0 +1,26 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.engine.framework.Engine;
+
+import java.util.UUID;
+
+public record PaletteExplorerStart(Engine engine, UUID worldId, UUID playerId, String biomeKey, double centerX, double centerZ) {
+}

core/src/main/java/com/volmit/iris/core/gui/PaletteInspectorPanel.java

@@ -0,0 +1,500 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.BorderFactory;
+import javax.swing.ButtonGroup;
+import javax.swing.JButton;
+import javax.swing.JComponent;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JToggleButton;
+import javax.swing.SwingConstants;
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.GridLayout;
+import java.awt.RenderingHints;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+
+final class PaletteInspectorPanel extends JPanel {
+    private static final long serialVersionUID = 4473102938518712001L;
+    private static final int PANEL_WIDTH = 310;
+    private static final Color HISTOGRAM_BAR = new Color(0x9D, 0xA0, 0xA8, 150);
+    private static final Color BAND_DIVIDER = new Color(255, 255, 255, 70);
+
+    private final Listener listener;
+    private final JLabel titleLabel = new JLabel();
+    private final JLabel detailLabel = new JLabel();
+    private final JLabel depthLabel = new JLabel("", SwingConstants.CENTER);
+    private final JButton shallowerButton = new JButton("‹");
+    private final JButton deeperButton = new JButton("›");
+    private final JPanel depthRow = new JPanel(new BorderLayout(StudioTheme.scale(6), 0));
+    private final StatisticsView statisticsView = new StatisticsView();
+    private PaletteLayerScale.View selectedView = PaletteLayerScale.View.BLOCKS;
+    private int depth;
+    private int deepestDepth;
+
+    PaletteInspectorPanel(Listener listener) {
+        super(new BorderLayout());
+        this.listener = listener;
+        setPreferredSize(StudioTheme.scaledSize(PANEL_WIDTH, 0));
+        setBorder(BorderFactory.createMatteBorder(0, 1, 0, 0, StudioTheme.SEPARATOR));
+        add(buildControls(), BorderLayout.NORTH);
+        add(StudioToolbar.scroll(statisticsView), BorderLayout.CENTER);
+        setVisible(false);
+    }
+
+    void showPreview(PaletteLayerPreview preview) {
+        titleLabel.setText(preview.biomeKey() + " · " + preview.palette().lowercaseLabel());
+        detailLabel.setText(placementText(preview));
+        depth = preview.depth();
+        deepestDepth = Math.max(0, preview.maxThickness() - 1);
+        refreshDepthControls();
+        statisticsView.show(preview);
+        setVisible(true);
+    }
+
+    void showTextureStatus(String status) {
+        statisticsView.showTextureStatus(status);
+    }
+
+    void hideInspector() {
+        setVisible(false);
+    }
+
+    PaletteLayerScale.View selectedView() {
+        return selectedView;
+    }
+
+    private JPanel buildControls() {
+        JPanel controls = new JPanel(new GridLayout(0, 1, 0, StudioTheme.scale(6)));
+        controls.setBorder(BorderFactory.createCompoundBorder(
+                BorderFactory.createMatteBorder(0, 0, 1, 0, StudioTheme.SEPARATOR),
+                StudioTheme.emptyBorder(12, 14, 12, 14)
+        ));
+        titleLabel.setFont(StudioTheme.titleFont());
+        detailLabel.setForeground(StudioTheme.SECONDARY_TEXT);
+        detailLabel.setFont(StudioTheme.smallFont());
+        controls.add(titleLabel);
+        controls.add(detailLabel);
+
+        controls.add(sectionLabel("Show"));
+        controls.add(buildViewButtons());
+        controls.add(sectionLabel("Depth"));
+        controls.add(buildDepthRow());
+        return controls;
+    }
+
+    private JPanel buildViewButtons() {
+        JPanel row = new JPanel(new GridLayout(1, 0, StudioTheme.scale(4), 0));
+        row.setOpaque(false);
+        ButtonGroup group = new ButtonGroup();
+        for (PaletteLayerScale.View view : PaletteLayerScale.View.values()) {
+            JToggleButton button = new JToggleButton(view.toString());
+            button.setFocusable(false);
+            button.setSelected(view == selectedView);
+            button.addActionListener(event -> {
+                selectedView = view;
+                listener.onViewChanged(view);
+            });
+            group.add(button);
+            row.add(button);
+        }
+        return row;
+    }
+
+    private JPanel buildDepthRow() {
+        depthRow.setOpaque(false);
+        shallowerButton.setToolTipText("Show the block one higher up");
+        deeperButton.setToolTipText("Show the block one further down");
+        shallowerButton.addActionListener(event -> changeDepth(-1));
+        deeperButton.addActionListener(event -> changeDepth(1));
+        depthRow.add(shallowerButton, BorderLayout.WEST);
+        depthRow.add(depthLabel, BorderLayout.CENTER);
+        depthRow.add(deeperButton, BorderLayout.EAST);
+        return depthRow;
+    }
+
+    private void changeDepth(int step) {
+        int nextDepth = Math.clamp(depth + step, 0, deepestDepth);
+        if (nextDepth == depth) {
+            return;
+        }
+        depth = nextDepth;
+        refreshDepthControls();
+        listener.onDepthChanged(depth);
+    }
+
+    private void refreshDepthControls() {
+        depthLabel.setText(depthText(depth, deepestDepth));
+        shallowerButton.setEnabled(depth > 0);
+        deeperButton.setEnabled(depth < deepestDepth);
+    }
+
+    private static JLabel sectionLabel(String text) {
+        JLabel label = new JLabel(text.toUpperCase(Locale.ROOT));
+        label.setForeground(StudioTheme.MUTED_TEXT);
+        label.setFont(StudioTheme.sectionFont());
+        return label;
+    }
+
+    // Stacked layers divide their coordinates by the zoom twice before sampling; wall and slab blocks only once.
+    private static String placementText(PaletteLayerPreview preview) {
+        if (!preview.palette().kind().isStacked()) {
+            return "Single blocks · zoom " + formatZoom(preview.zoom());
+        }
+        return thicknessText(preview) + " · zoom " + formatZoom(preview.zoom())
+                + " (×" + formatZoom(preview.zoom() * preview.zoom()) + " effective)";
+    }
+
+    private static String thicknessText(PaletteLayerPreview preview) {
+        if (preview.minThickness() == preview.maxThickness()) {
+            return preview.maxThickness() + (preview.maxThickness() == 1 ? " block thick" : " blocks thick");
+        }
+        return preview.minThickness() + "–" + preview.maxThickness() + " blocks thick";
+    }
+
+    private static String depthText(int depth, int deepestDepth) {
+        if (deepestDepth == 0) {
+            return "Top block only";
+        }
+        return depth == 0 ? "Top block" : depth + (depth == 1 ? " block down" : " blocks down");
+    }
+
+    private static String formatZoom(double zoom) {
+        return zoom == Math.rint(zoom) ? Long.toString((long) zoom) : String.format(Locale.ROOT, "%.2f", zoom);
+    }
+
+    private static String percent(double share) {
+        if (share > 0D && share < 0.001D) {
+            return "<0.1%";
+        }
+        return String.format(Locale.ROOT, "%.1f%%", share * 100D);
+    }
+
+    interface Listener {
+        void onViewChanged(PaletteLayerScale.View view);
+
+        void onDepthChanged(int depth);
+    }
+
+    private static final class StatisticsView extends JComponent {
+        private static final long serialVersionUID = -2318840125766150871L;
+        private static final int MARGIN = 14;
+        private static final int HISTOGRAM_HEIGHT = 84;
+        private static final int BAND_HEIGHT = 12;
+        private static final int SECTION_GAP = 18;
+        private static final int TITLE_GAP = 6;
+        private static final int NOTE_GAP = 4;
+        private static final String WIDEST_WEIGHT = "100.0%";
+        private static final String WIDEST_ACTUAL = "▲ 100.0%";
+
+        private PaletteLayerPreview preview;
+        private String textureStatus;
+
+        private StatisticsView() {
+            setOpaque(true);
+            setBackground(StudioTheme.PANEL_BACKGROUND);
+        }
+
+        private void show(PaletteLayerPreview nextPreview) {
+            preview = nextPreview;
+            revalidate();
+            repaint();
+        }
+
+        private void showTextureStatus(String status) {
+            textureStatus = status;
+            revalidate();
+            repaint();
+        }
+
+        @Override
+        public Dimension getPreferredSize() {
+            int preferredWidth = StudioTheme.scale(PANEL_WIDTH - 20);
+            if (preview == null) {
+                return new Dimension(preferredWidth, 0);
+            }
+            int margin = StudioTheme.scale(MARGIN);
+            int width = Math.max(getWidth(), preferredWidth) - margin * 2;
+            int height = margin + valueSpreadHeight() + StudioTheme.scale(SECTION_GAP) + blockTableHeight()
+                    + StudioTheme.scale(SECTION_GAP) + notesHeight(width) + margin;
+            return new Dimension(preferredWidth, height);
+        }
+
+        @Override
+        protected void paintComponent(Graphics graphics) {
+            Graphics2D canvas = (Graphics2D) graphics.create();
+            try {
+                canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+                canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+                canvas.setColor(StudioTheme.PANEL_BACKGROUND);
+                canvas.fillRect(0, 0, getWidth(), getHeight());
+                if (preview == null) {
+                    return;
+                }
+                int margin = StudioTheme.scale(MARGIN);
+                int width = getWidth() - margin * 2;
+                int top = margin;
+                drawValueSpread(canvas, margin, top, width);
+                top += valueSpreadHeight() + StudioTheme.scale(SECTION_GAP);
+                drawBlockTable(canvas, margin, top, width);
+                top += blockTableHeight() + StudioTheme.scale(SECTION_GAP);
+                drawNotes(canvas, margin, top, width);
+            } finally {
+                canvas.dispose();
+            }
+        }
+
+        private int valueSpreadHeight() {
+            return sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP) + StudioTheme.scale(HISTOGRAM_HEIGHT)
+                    + StudioTheme.scale(2) + StudioTheme.scale(BAND_HEIGHT) + StudioTheme.scale(3) + smallMetrics().getHeight();
+        }
+
+        private int blockTableHeight() {
+            return sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP) + rowHeight() * preview.entries().size();
+        }
+
+        private int notesHeight(int width) {
+            FontMetrics metrics = smallMetrics();
+            int height = 0;
+            for (String note : notes()) {
+                height += wrap(note, metrics, width).size() * metrics.getHeight() + StudioTheme.scale(NOTE_GAP);
+            }
+            return height;
+        }
+
+        private int rowHeight() {
+            return textMetrics().getHeight() + StudioTheme.scale(4);
+        }
+
+        private FontMetrics textMetrics() {
+            return getFontMetrics(StudioTheme.font());
+        }
+
+        private FontMetrics smallMetrics() {
+            return getFontMetrics(StudioTheme.smallFont());
+        }
+
+        private FontMetrics sectionMetrics() {
+            return getFontMetrics(StudioTheme.sectionFont());
+        }
+
+        private void drawValueSpread(Graphics2D canvas, int x, int top, int width) {
+            drawSectionTitle(canvas, "Noise values this layer produces", x, top + sectionMetrics().getAscent());
+            int histogramTop = top + sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP);
+            int histogramHeight = StudioTheme.scale(HISTOGRAM_HEIGHT);
+            int bandHeight = StudioTheme.scale(BAND_HEIGHT);
+            long[] histogram = preview.histogram();
+            long peak = 1L;
+            for (long count : histogram) {
+                peak = Math.max(peak, count);
+            }
+            canvas.setColor(HISTOGRAM_BAR);
+            for (int bin = 0; bin < histogram.length; bin++) {
+                int barLeft = x + (bin * width) / histogram.length;
+                int barRight = x + ((bin + 1) * width) / histogram.length;
+                int barHeight = (int) Math.round(histogramHeight * (histogram[bin] / (double) peak));
+                canvas.fillRect(barLeft, histogramTop + histogramHeight - barHeight, Math.max(1, barRight - barLeft - 1), barHeight);
+            }
+
+            int bandTop = histogramTop + histogramHeight + StudioTheme.scale(2);
+            for (PaletteLayerPreview.Entry entry : preview.entries()) {
+                if (Double.isNaN(entry.lowestNoise())) {
+                    continue;
+                }
+                int bandLeft = x + (int) Math.round(entry.lowestNoise() * width);
+                int bandRight = x + (int) Math.round(entry.highestNoise() * width);
+                canvas.setColor(new Color(entry.color()));
+                canvas.fillRect(bandLeft, bandTop, Math.max(1, bandRight - bandLeft), bandHeight);
+                if (entry.highestNoise() < 1D) {
+                    canvas.setColor(BAND_DIVIDER);
+                    canvas.drawLine(bandRight, histogramTop, bandRight, bandTop + bandHeight - 1);
+                }
+            }
+
+            canvas.setFont(StudioTheme.smallFont());
+            canvas.setColor(StudioTheme.SECONDARY_TEXT);
+            FontMetrics metrics = canvas.getFontMetrics();
+            int labelY = bandTop + bandHeight + StudioTheme.scale(3) + metrics.getAscent();
+            canvas.drawString("0", x, labelY);
+            canvas.drawString("0.5", x + (width - metrics.stringWidth("0.5")) / 2, labelY);
+            canvas.drawString("1", x + width - metrics.stringWidth("1"), labelY);
+        }
+
+        private void drawBlockTable(Graphics2D canvas, int x, int top, int width) {
+            int columnGap = StudioTheme.scale(10);
+            int actualRight = x + width;
+            int weightRight = actualRight - textMetrics().stringWidth(WIDEST_ACTUAL) - columnGap;
+            int nameRight = weightRight - textMetrics().stringWidth(WIDEST_WEIGHT) - columnGap;
+            int titleBaseline = top + sectionMetrics().getAscent();
+            drawSectionTitle(canvas, "Blocks", x, titleBaseline);
+            drawRightAligned(canvas, "weight", weightRight, titleBaseline);
+            drawRightAligned(canvas, "actual", actualRight, titleBaseline);
+
+            int rowHeight = rowHeight();
+            FontMetrics text = textMetrics();
+            int swatchSize = text.getAscent() - text.getDescent();
+            int rowTop = top + sectionMetrics().getHeight() + StudioTheme.scale(TITLE_GAP);
+            for (PaletteLayerPreview.Entry entry : preview.entries()) {
+                int baseline = rowTop + (rowHeight + text.getAscent() - text.getDescent()) / 2;
+                drawSwatch(canvas, entry, x, rowTop + (rowHeight - swatchSize) / 2, swatchSize);
+                canvas.setFont(StudioTheme.font());
+                canvas.setColor(entry.found() ? StudioTheme.TEXT : StudioTheme.ERROR);
+                String name = entry.found() ? shortBlockName(entry.block()) : shortBlockName(entry.block()) + " (not found)";
+                int nameLeft = x + swatchSize + StudioTheme.scale(7);
+                canvas.drawString(fit(canvas, name, nameRight - nameLeft), nameLeft, baseline);
+                canvas.setColor(StudioTheme.SECONDARY_TEXT);
+                drawRightAligned(canvas, percent(entry.weightShare()), weightRight, baseline);
+                canvas.setColor(actualColor(entry));
+                drawRightAligned(canvas, actualText(entry), actualRight, baseline);
+                rowTop += rowHeight;
+            }
+        }
+
+        private static void drawSwatch(Graphics2D canvas, PaletteLayerPreview.Entry entry, int x, int y, int size) {
+            if (entry.texture() != null) {
+                canvas.drawImage(entry.texture().toImage(), x, y, size, size, null);
+                return;
+            }
+            canvas.setColor(new Color(entry.color()));
+            int arc = StudioTheme.scale(3);
+            canvas.fillRoundRect(x, y, size, size, arc, arc);
+        }
+
+        private void drawNotes(Graphics2D canvas, int x, int top, int width) {
+            canvas.setFont(StudioTheme.smallFont());
+            canvas.setColor(StudioTheme.SECONDARY_TEXT);
+            FontMetrics metrics = canvas.getFontMetrics();
+            int lineY = top + metrics.getAscent();
+            for (String note : notes()) {
+                for (String line : wrap(note, metrics, width)) {
+                    canvas.drawString(line, x, lineY);
+                    lineY += metrics.getHeight();
+                }
+                lineY += StudioTheme.scale(NOTE_GAP);
+            }
+        }
+
+        private List<String> notes() {
+            List<String> notes = new ArrayList<>();
+            if (textureStatus != null) {
+                notes.add(textureStatus);
+            }
+            notes.add("▼ gets under half its weight, ▲ gets over double.");
+            notes.add(String.format(Locale.ROOT, "Measured on a %d × %d grid spread over %,.0f blocks around 0, 0.",
+                    PaletteLayerPreview.STATISTICS_GRID_SIZE, PaletteLayerPreview.STATISTICS_GRID_SIZE,
+                    PaletteLayerPreview.statisticsAreaBlocks()));
+            if (preview.absentShare() > 0D) {
+                notes.add(absentText(preview) + " That ground is dark on the map and left out of the shares.");
+            }
+            if (preview.outOfRangeShare() > 0D) {
+                notes.add(percent(preview.outOfRangeShare()) + " of the noise values fall outside 0 to 1."
+                        + " Those spots get the first block.");
+            }
+            if (preview.simplification() != null) {
+                notes.add(preview.simplification());
+            }
+            if (preview.hasSlopeCondition()) {
+                notes.add("This " + paletteNoun(preview) + " has a slope condition, which the preview ignores.");
+            }
+            return notes;
+        }
+
+        private static String absentText(PaletteLayerPreview preview) {
+            if (isDecorator(preview)) {
+                return "The decorator leaves " + percent(preview.absentShare()) + " of the ground bare.";
+            }
+            return "The layer doesn't reach this depth on " + percent(preview.absentShare()) + " of the ground.";
+        }
+
+        private static String paletteNoun(PaletteLayerPreview preview) {
+            return isDecorator(preview) ? "decorator" : "layer";
+        }
+
+        private static boolean isDecorator(PaletteLayerPreview preview) {
+            return preview.palette().kind() == BiomePalette.Kind.DECORATOR;
+        }
+
+        private static String actualText(PaletteLayerPreview.Entry entry) {
+            if (entry.isFarBelowWeight()) {
+                return "▼ " + percent(entry.actualShare());
+            }
+            if (entry.isFarAboveWeight()) {
+                return "▲ " + percent(entry.actualShare());
+            }
+            return percent(entry.actualShare());
+        }
+
+        private static Color actualColor(PaletteLayerPreview.Entry entry) {
+            return entry.isFarBelowWeight() || entry.isFarAboveWeight() ? StudioTheme.WARNING : StudioTheme.TEXT;
+        }
+
+        private static void drawSectionTitle(Graphics2D canvas, String title, int x, int y) {
+            canvas.setFont(StudioTheme.sectionFont());
+            canvas.setColor(StudioTheme.MUTED_TEXT);
+            canvas.drawString(title.toUpperCase(Locale.ROOT), x, y);
+        }
+
+        private static void drawRightAligned(Graphics2D canvas, String text, int right, int y) {
+            canvas.drawString(text, right - canvas.getFontMetrics().stringWidth(text), y);
+        }
+
+        private static String shortBlockName(String block) {
+            return block.startsWith("minecraft:") ? block.substring("minecraft:".length()) : block;
+        }
+
+        private static String fit(Graphics2D canvas, String text, int maxWidth) {
+            FontMetrics metrics = canvas.getFontMetrics();
+            if (metrics.stringWidth(text) <= maxWidth) {
+                return text;
+            }
+            String shortened = text;
+            while (shortened.length() > 1 && metrics.stringWidth(shortened + "…") > maxWidth) {
+                shortened = shortened.substring(0, shortened.length() - 1);
+            }
+            return shortened + "…";
+        }
+
+        private static List<String> wrap(String text, FontMetrics metrics, int maxWidth) {
+            List<String> lines = new ArrayList<>();
+            StringBuilder line = new StringBuilder();
+            for (String word : text.split(" ")) {
+                String candidate = line.isEmpty() ? word : line + " " + word;
+                if (metrics.stringWidth(candidate) > maxWidth && !line.isEmpty()) {
+                    lines.add(line.toString());
+                    line = new StringBuilder(word);
+                } else {
+                    line = new StringBuilder(candidate);
+                }
+            }
+            if (!line.isEmpty()) {
+                lines.add(line.toString());
+            }
+            return lines;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PaletteLayerPreview.java

@@ -0,0 +1,457 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.BlockTextures.BlockTexture;
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisBiomePaletteLayer;
+import com.volmit.iris.engine.object.IrisBlockData;
+import com.volmit.iris.util.collection.KList;
+import com.volmit.iris.util.math.RNG;
+import org.bukkit.block.data.BlockData;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+
+final class PaletteLayerPreview {
+    static final int HISTOGRAM_BINS = 50;
+    static final int STATISTICS_GRID_SIZE = 64;
+    static final double STATISTICS_SPACING_BLOCKS = 37D;
+    private static final int MISSING_BLOCK_COLOR = 0x5A5F6B;
+    private static final double FAR_FROM_WEIGHT_FACTOR = 2D;
+    private static final int BLOCK_CACHE_SIZE = 1 << 16;
+    private static final int NO_OVERHANG = -1;
+
+    private final BiomePalette palette;
+    private final KList<IrisBlockData> blocks;
+    private final BiomePalettePlacement placement;
+    private final PaletteLayerPreview ground;
+    private final boolean[] showsGroundByEntry;
+    private final int depth;
+    private final IrisData data;
+    private final int[] entryBySlot;
+    private final BiomeTintField biomeTints;
+    private final BlockTexture[] textureByEntry;
+    private final BlockTexture[] upperHalfByEntry;
+    private final boolean hasTallPlants;
+    private final BlockTexture[] legendTextureByEntry;
+    private final int[] legendColorByEntry;
+    private final List<Entry> entries;
+    private final SampledBlock[] blockCache = new SampledBlock[BLOCK_CACHE_SIZE];
+    private final long[] histogram;
+    private final double absentShare;
+    private final double outOfRangeShare;
+
+    private PaletteLayerPreview(BiomePalette palette, BiomePalettePlacement placement, PaletteLayerPreview ground, int depth,
+                                IrisData data, BlockTextures textures, BiomeTintField biomeTints) {
+        this.palette = palette;
+        this.blocks = placement.blocks();
+        this.placement = placement;
+        this.ground = ground;
+        this.depth = depth;
+        this.data = data;
+        this.entryBySlot = IrisBiomePaletteLayer.paletteEntryPerSlot(blocks, data).stream().mapToInt(Integer::intValue).toArray();
+        if (entryBySlot.length == 0) {
+            throw new IllegalStateException("No block of " + palette.biomeKey() + " " + palette.lowercaseLabel() + " could be found");
+        }
+        this.biomeTints = biomeTints;
+        this.showsGroundByEntry = resolveGroundShowingEntries();
+        this.textureByEntry = resolveEntryTextures(textures);
+        this.upperHalfByEntry = resolveUpperHalves(textures);
+        this.hasTallPlants = Arrays.stream(upperHalfByEntry).anyMatch(Objects::nonNull);
+        this.legendTextureByEntry = tintForLegend(legendTextures());
+        this.legendColorByEntry = resolveLegendColors();
+
+        Statistics statistics = measure();
+        this.histogram = statistics.histogram();
+        this.absentShare = statistics.absentShare();
+        this.outOfRangeShare = statistics.outOfRangeShare();
+        this.entries = describeEntries(statistics.sharesByEntry());
+    }
+
+    static PaletteLayerPreview load(Engine engine, BiomePalette palette, int depth, BlockTextures textures) {
+        if (engine == null || engine.isClosed()) {
+            throw new IllegalStateException("Open a studio world to preview pack palettes");
+        }
+        IrisData data = engine.getData();
+        IrisBiome biome = data.getBiomeLoader().load(palette.biomeKey());
+        if (biome == null || palette.blocksIn(biome) == null) {
+            throw new IllegalStateException("Palette removed during hotload: " + palette.biomeKey() + " " + palette.lowercaseLabel());
+        }
+        BiomePalettePlacement placement = BiomePalettePlacement.of(engine, biome, palette);
+        BiomeTintField biomeTints = textures == null
+                ? null
+                : new BiomeTintField(biome, new RNG(engine.getSeedManager().getBiome()), textures.biomeColors());
+        PaletteLayerPreview ground = palette.kind() == BiomePalette.Kind.DECORATOR
+                ? groundUnder(engine, palette.biomeKey(), biome, data, textures, biomeTints)
+                : null;
+        return new PaletteLayerPreview(palette, placement, ground, depth, data, textures, biomeTints);
+    }
+
+    // Decorations stand on the biome's top surface layer, so that is what shows around and between them.
+    private static PaletteLayerPreview groundUnder(Engine engine, String biomeKey, IrisBiome biome, IrisData data,
+                                                   BlockTextures textures, BiomeTintField biomeTints) {
+        BiomePalette topLayer = new BiomePalette(biomeKey, BiomePalette.Kind.LAYER, 0);
+        KList<IrisBlockData> blocks = topLayer.blocksIn(biome);
+        if (blocks == null || blocks.isEmpty()) {
+            return null;
+        }
+        return new PaletteLayerPreview(topLayer, BiomePalettePlacement.of(engine, biome, topLayer), null, 0, data, textures,
+                biomeTints);
+    }
+
+    // The world picks one block per whole coordinate, and zoomed in, many pixels fall on the same block.
+    double sample(double x, double z) {
+        int blockX = (int) Math.floor(x);
+        int blockZ = (int) Math.floor(z);
+        int cacheSlot = blockCacheSlot(blockX, blockZ);
+        SampledBlock cached = blockCache[cacheSlot];
+        if (cached != null && cached.x() == blockX && cached.z() == blockZ) {
+            return cached.noise();
+        }
+        double noise = sampleBlock(blockX, blockZ);
+        blockCache[cacheSlot] = new SampledBlock(blockX, blockZ, noise);
+        return noise;
+    }
+
+    private double sampleBlock(int blockX, int blockZ) {
+        if (placement.thickness(blockX, blockZ) <= depth) {
+            return Double.NaN;
+        }
+        return placement.noise(blockX, blockZ, depth);
+    }
+
+    private static int blockCacheSlot(int blockX, int blockZ) {
+        long hash = blockX * 0x9E3779B97F4A7C15L ^ blockZ * 0xC2B2AE3D27D4EB4FL;
+        return (int) ((hash ^ (hash >>> 29)) & (BLOCK_CACHE_SIZE - 1));
+    }
+
+    int colorForNoise(double noise) {
+        return legendColorByEntry[entryIndexForNoise(noise)];
+    }
+
+    int blockColorAt(double noise, double worldX, double worldZ, boolean showTexturePixels) {
+        int overhang = showTexturePixels ? overhangColorAt(worldX, worldZ) : NO_OVERHANG;
+        if (overhang != NO_OVERHANG) {
+            return overhang;
+        }
+        int entry = entryIndexForNoise(noise);
+        if (showsGroundByEntry[entry]) {
+            return bareColorAt(worldX, worldZ, showTexturePixels);
+        }
+        BlockTexture texture = textureByEntry[entry];
+        if (texture == null) {
+            return legendColorByEntry[entry];
+        }
+        if (ground != null && showTexturePixels && !texture.isOpaqueAt(worldX, worldZ)) {
+            return groundColorAt(worldX, worldZ, true);
+        }
+        int untintedColor = showTexturePixels ? texture.texelAt(worldX, worldZ) : texture.averageColor();
+        return tinted(texture, untintedColor, worldX, worldZ);
+    }
+
+    /**
+     * The colour where the palette places nothing: the ground under a decorator, or plain dark otherwise.
+     */
+    int bareColorAt(double worldX, double worldZ, boolean showTexturePixels) {
+        if (ground == null) {
+            return PaletteLayerScale.ABSENT_COLOR;
+        }
+        int overhang = showTexturePixels ? overhangColorAt(worldX, worldZ) : NO_OVERHANG;
+        return overhang != NO_OVERHANG ? overhang : groundColorAt(worldX, worldZ, showTexturePixels);
+    }
+
+    // A two block tall plant stands up on the map: its top half covers the block above it, which is one block north.
+    private int overhangColorAt(double worldX, double worldZ) {
+        if (!hasTallPlants) {
+            return NO_OVERHANG;
+        }
+        double plantZ = worldZ + 1D;
+        double noise = sample(worldX, plantZ);
+        if (Double.isNaN(noise)) {
+            return NO_OVERHANG;
+        }
+        BlockTexture upperHalf = upperHalfByEntry[entryIndexForNoise(noise)];
+        if (upperHalf == null || !upperHalf.isOpaqueAt(worldX, worldZ)) {
+            return NO_OVERHANG;
+        }
+        return tinted(upperHalf, upperHalf.texelAt(worldX, worldZ), worldX, plantZ);
+    }
+
+    private int tinted(BlockTexture texture, int untintedColor, double worldX, double worldZ) {
+        if (texture.biomeTint() == null) {
+            return untintedColor;
+        }
+        int tint = biomeTints.colorAt(texture.biomeTint(), (int) Math.floor(worldX), (int) Math.floor(worldZ));
+        return BlockTexture.multiply(untintedColor, tint);
+    }
+
+    private int groundColorAt(double worldX, double worldZ, boolean showTexturePixels) {
+        double noise = ground.sample(worldX, worldZ);
+        return Double.isNaN(noise) ? PaletteLayerScale.ABSENT_COLOR : ground.blockColorAt(noise, worldX, worldZ, showTexturePixels);
+    }
+
+    // A decorator places air to leave gaps, which looks the same as placing nothing.
+    private boolean[] resolveGroundShowingEntries() {
+        boolean[] showsGround = new boolean[blocks.size()];
+        for (int entry = 0; entry < blocks.size(); entry++) {
+            BlockData block = blocks.get(entry).getBlockData(data);
+            showsGround[entry] = ground != null && block != null && block.getMaterial().isAir();
+        }
+        return showsGround;
+    }
+
+    Entry entryForNoise(double noise) {
+        return entries.get(entryIndexForNoise(noise));
+    }
+
+    String biomeKey() {
+        return palette.biomeKey();
+    }
+
+    BiomePalette palette() {
+        return palette;
+    }
+
+    String simplification() {
+        return placement.simplification();
+    }
+
+    int depth() {
+        return depth;
+    }
+
+    int minThickness() {
+        return placement.minThickness();
+    }
+
+    int maxThickness() {
+        return placement.maxThickness();
+    }
+
+    double zoom() {
+        return placement.zoom();
+    }
+
+    boolean hasSlopeCondition() {
+        return placement.hasSlopeCondition();
+    }
+
+    List<Entry> entries() {
+        return entries;
+    }
+
+    long[] histogram() {
+        return histogram.clone();
+    }
+
+    double absentShare() {
+        return absentShare;
+    }
+
+    double outOfRangeShare() {
+        return outOfRangeShare;
+    }
+
+    static double statisticsAreaBlocks() {
+        return STATISTICS_GRID_SIZE * STATISTICS_SPACING_BLOCKS;
+    }
+
+    private int entryIndexForNoise(double noise) {
+        return entryBySlot[IrisBiomePaletteLayer.slotForNoise(noise, entryBySlot.length)];
+    }
+
+    private BlockTexture[] resolveEntryTextures(BlockTextures textures) {
+        BlockTexture[] resolved = new BlockTexture[blocks.size()];
+        if (textures == null) {
+            return resolved;
+        }
+        for (int entry = 0; entry < blocks.size(); entry++) {
+            BlockData block = blocks.get(entry).getBlockData(data);
+            resolved[entry] = block == null ? null : textureOf(block, textures).orElse(null);
+        }
+        return resolved;
+    }
+
+    private BlockTexture[] resolveUpperHalves(BlockTextures textures) {
+        BlockTexture[] resolved = new BlockTexture[blocks.size()];
+        if (textures == null || palette.kind() != BiomePalette.Kind.DECORATOR) {
+            return resolved;
+        }
+        for (int entry = 0; entry < blocks.size(); entry++) {
+            BlockData block = blocks.get(entry).getBlockData(data);
+            resolved[entry] = block == null ? null : textures.upperHalfIcon(block).orElse(null);
+        }
+        return resolved;
+    }
+
+    // Tall plants are known by their top half, the way Minecraft draws them in the inventory.
+    private BlockTexture[] legendTextures() {
+        BlockTexture[] legend = textureByEntry.clone();
+        for (int entry = 0; entry < legend.length; entry++) {
+            if (upperHalfByEntry[entry] != null) {
+                legend[entry] = upperHalfByEntry[entry];
+            }
+        }
+        return legend;
+    }
+
+    private Optional<BlockTexture> textureOf(BlockData block, BlockTextures textures) {
+        return palette.kind() == BiomePalette.Kind.DECORATOR ? textures.iconTexture(block) : textures.topTexture(block);
+    }
+
+    // The legend shows tinted blocks as they look at the world origin, where the statistics are sampled too.
+    private BlockTexture[] tintForLegend(BlockTexture[] textures) {
+        BlockTexture[] tinted = new BlockTexture[textures.length];
+        for (int entry = 0; entry < textures.length; entry++) {
+            BlockTexture texture = textures[entry];
+            tinted[entry] = texture == null || texture.biomeTint() == null
+                    ? texture
+                    : texture.tinted(biomeTints.colorAt(texture.biomeTint(), 0, 0));
+        }
+        return tinted;
+    }
+
+    // Blocks without a texture, like custom blocks or everything before the textures load, fall back to map colours.
+    private int[] resolveLegendColors() {
+        List<BlockData> untexturedBlocks = new ArrayList<>();
+        for (int entry = 0; entry < blocks.size(); entry++) {
+            BlockData block = blocks.get(entry).getBlockData(data);
+            if (block != null && textureByEntry[entry] == null) {
+                untexturedBlocks.add(block);
+            }
+        }
+        Map<String, Integer> mapColorsByBlock = BlockPreviewColors.colorsByBlock(untexturedBlocks);
+        int[] colors = new int[blocks.size()];
+        for (int entry = 0; entry < blocks.size(); entry++) {
+            BlockData block = blocks.get(entry).getBlockData(data);
+            if (block == null) {
+                colors[entry] = MISSING_BLOCK_COLOR;
+            } else if (legendTextureByEntry[entry] != null) {
+                colors[entry] = legendTextureByEntry[entry].averageColor();
+            } else {
+                colors[entry] = mapColorsByBlock.get(block.getAsString(true));
+            }
+        }
+        return colors;
+    }
+
+    private Statistics measure() {
+        long[] values = new long[HISTOGRAM_BINS];
+        long[] samplesByEntry = new long[blocks.size()];
+        long present = 0;
+        long absent = 0;
+        long outOfRange = 0;
+        double origin = -statisticsAreaBlocks() / 2D;
+        for (int gridX = 0; gridX < STATISTICS_GRID_SIZE; gridX++) {
+            for (int gridZ = 0; gridZ < STATISTICS_GRID_SIZE; gridZ++) {
+                double noise = sample(origin + gridX * STATISTICS_SPACING_BLOCKS, origin + gridZ * STATISTICS_SPACING_BLOCKS);
+                if (Double.isNaN(noise)) {
+                    absent++;
+                    continue;
+                }
+                present++;
+                if (noise < 0D || noise > 1D) {
+                    outOfRange++;
+                }
+                values[Math.clamp((int) (noise * HISTOGRAM_BINS), 0, HISTOGRAM_BINS - 1)]++;
+                samplesByEntry[entryIndexForNoise(noise)]++;
+            }
+        }
+        double[] sharesByEntry = new double[samplesByEntry.length];
+        for (int entry = 0; entry < samplesByEntry.length; entry++) {
+            sharesByEntry[entry] = present == 0 ? 0D : samplesByEntry[entry] / (double) present;
+        }
+        long total = present + absent;
+        return new Statistics(values, sharesByEntry, absent / (double) total, present == 0 ? 0D : outOfRange / (double) present);
+    }
+
+    private List<Entry> describeEntries(double[] sharesByEntry) {
+        int slotCount = entryBySlot.length;
+        List<Entry> described = new ArrayList<>(blocks.size());
+        for (int entry = 0; entry < blocks.size(); entry++) {
+            IrisBlockData block = blocks.get(entry);
+            int firstSlot = firstSlotOf(entry);
+            int lastSlot = lastSlotOf(entry);
+            boolean placed = firstSlot >= 0;
+            described.add(new Entry(
+                    block.getBlock(),
+                    block.getWeight(),
+                    block.getBlockData(data) != null,
+                    legendColorByEntry[entry],
+                    legendTextureByEntry[entry],
+                    placed ? (lastSlot - firstSlot + 1) / (double) slotCount : 0D,
+                    sharesByEntry[entry],
+                    placed ? slotLowerBound(firstSlot, slotCount) : Double.NaN,
+                    placed ? slotUpperBound(lastSlot, slotCount) : Double.NaN
+            ));
+        }
+        return List.copyOf(described);
+    }
+
+    private int firstSlotOf(int entry) {
+        for (int slot = 0; slot < entryBySlot.length; slot++) {
+            if (entryBySlot[slot] == entry) {
+                return slot;
+            }
+        }
+        return -1;
+    }
+
+    private int lastSlotOf(int entry) {
+        for (int slot = entryBySlot.length - 1; slot >= 0; slot--) {
+            if (entryBySlot[slot] == entry) {
+                return slot;
+            }
+        }
+        return -1;
+    }
+
+    // Slots are picked by rounding, so the first and last slot only own half a step of the value range.
+    private static double slotLowerBound(int slot, int slotCount) {
+        return slot == 0 ? 0D : (slot - 0.5D) / (slotCount - 1);
+    }
+
+    private static double slotUpperBound(int slot, int slotCount) {
+        return slot == slotCount - 1 ? 1D : (slot + 0.5D) / (slotCount - 1);
+    }
+
+    record Entry(String block, int weight, boolean found, int color, BlockTexture texture, double weightShare,
+                 double actualShare, double lowestNoise, double highestNoise) {
+        boolean isFarBelowWeight() {
+            return found && actualShare < weightShare / FAR_FROM_WEIGHT_FACTOR;
+        }
+
+        boolean isFarAboveWeight() {
+            return found && actualShare > weightShare * FAR_FROM_WEIGHT_FACTOR;
+        }
+    }
+
+    private record SampledBlock(int x, int z, double noise) {
+    }
+
+    private record Statistics(long[] histogram, double[] sharesByEntry, double absentShare, double outOfRangeShare) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PaletteLayerScale.java

@@ -0,0 +1,107 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import java.awt.Color;
+
+final class PaletteLayerScale implements NoiseColorScale {
+    static final int ABSENT_COLOR = 0x161A24;
+    private static final double OVERLAY_DARKEST_SHADE = 0.3D;
+
+    private final View view;
+    private final PaletteLayerPreview preview;
+    private final NoisePalette noisePalette;
+    private final boolean showTexturePixels;
+
+    PaletteLayerScale(View view, PaletteLayerPreview preview, NoisePalette noisePalette, boolean showTexturePixels) {
+        this.view = view;
+        this.preview = preview;
+        this.noisePalette = noisePalette;
+        this.showTexturePixels = showTexturePixels;
+    }
+
+    @Override
+    public int colorAt(double value, double worldX, double worldZ) {
+        if (view == View.NOISE) {
+            return noisePalette.colorFinite(value);
+        }
+        int blockColor = preview.blockColorAt(value, worldX, worldZ, showTexturePixels);
+        return view == View.BLOCKS ? blockColor : BlockPreviewColors.shade(blockColor, overlayShade(value));
+    }
+
+    @Override
+    public int colorFinite(double value) {
+        return switch (view) {
+            case BLOCKS -> preview.colorForNoise(value);
+            case NOISE -> noisePalette.colorFinite(value);
+            case BLOCKS_SHADED_BY_NOISE -> BlockPreviewColors.shade(preview.colorForNoise(value), overlayShade(value));
+        };
+    }
+
+    @Override
+    public int colorInvalid() {
+        return ABSENT_COLOR;
+    }
+
+    @Override
+    public int colorInvalidAt(double worldX, double worldZ) {
+        return view == View.NOISE ? ABSENT_COLOR : preview.bareColorAt(worldX, worldZ, showTexturePixels);
+    }
+
+    @Override
+    public Color displayColorNormalized(double normalized) {
+        return new Color(colorFinite(minimum() + normalized * (maximum() - minimum())));
+    }
+
+    @Override
+    public String label() {
+        return view == View.NOISE ? noisePalette.label() : view.toString();
+    }
+
+    @Override
+    public double minimum() {
+        return view == View.NOISE ? noisePalette.minimum() : 0D;
+    }
+
+    @Override
+    public double maximum() {
+        return view == View.NOISE ? noisePalette.maximum() : 1D;
+    }
+
+    private static double overlayShade(double value) {
+        return OVERLAY_DARKEST_SHADE + (1D - OVERLAY_DARKEST_SHADE) * Math.clamp(value, 0D, 1D);
+    }
+
+    enum View {
+        BLOCKS("Blocks"),
+        NOISE("Noise"),
+        BLOCKS_SHADED_BY_NOISE("Both");
+
+        private final String label;
+
+        View(String label) {
+            this.label = label;
+        }
+
+        @Override
+        public String toString() {
+            return label;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PaletteNavigator.java

@@ -0,0 +1,527 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.PaletteCatalog.BiomeEntry;
+import com.volmit.iris.core.gui.PaletteCatalog.BiomeGroup;
+import com.volmit.iris.core.gui.PaletteCatalog.RegionEntry;
+import com.volmit.iris.core.gui.PlayerLocationTracker.PlayerLocation;
+
+import javax.swing.BorderFactory;
+import javax.swing.ButtonGroup;
+import javax.swing.DefaultListCellRenderer;
+import javax.swing.DefaultListModel;
+import javax.swing.JLabel;
+import javax.swing.JList;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+import javax.swing.JToggleButton;
+import javax.swing.JTree;
+import javax.swing.ListSelectionModel;
+import javax.swing.event.DocumentEvent;
+import javax.swing.event.DocumentListener;
+import javax.swing.tree.DefaultMutableTreeNode;
+import javax.swing.tree.DefaultTreeCellRenderer;
+import javax.swing.tree.DefaultTreeModel;
+import javax.swing.tree.TreePath;
+import javax.swing.tree.TreeSelectionModel;
+import java.awt.BorderLayout;
+import java.awt.CardLayout;
+import java.awt.Component;
+import java.awt.GridLayout;
+import java.awt.Rectangle;
+import java.util.Enumeration;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Set;
+
+
+final class PaletteNavigator extends JPanel {
+    private static final long serialVersionUID = -6402313718430917284L;
+    private static final String HERE_CARD = "here";
+    private static final String OVERVIEW_CARD = "overview";
+    private static final int MESSAGE_WRAP_WIDTH_PIXELS = 190;
+
+    private final Listener listener;
+    private final CardLayout cards = new CardLayout();
+    private final JPanel cardPanel = new JPanel(cards);
+    private final JLabel regionLabel = new JLabel();
+    private final DefaultListModel<HereRow> hereRows = new DefaultListModel<>();
+    private final JList<HereRow> hereList = new JList<>(hereRows);
+    private final JTextField searchField = new JTextField();
+    private final DefaultTreeModel treeModel = new DefaultTreeModel(new DefaultMutableTreeNode());
+    private final JTree overviewTree = new JTree(treeModel);
+
+    private PaletteCatalog catalog;
+    private PlayerLocation location;
+    private BiomePalette selectedPalette;
+    private boolean updatingSelection;
+    private boolean untracked;
+
+    PaletteNavigator(Listener listener) {
+        super(new BorderLayout());
+        this.listener = listener;
+        cardPanel.add(buildHereCard(), HERE_CARD);
+        cardPanel.add(buildOverviewCard(), OVERVIEW_CARD);
+        add(buildTabBar(), BorderLayout.NORTH);
+        add(cardPanel, BorderLayout.CENTER);
+        refreshHere();
+    }
+
+    void showCatalog(PaletteCatalog nextCatalog) {
+        catalog = nextCatalog;
+        rebuildOverview();
+        refreshHere();
+    }
+
+    void showLocation(PlayerLocation nextLocation) {
+        location = nextLocation;
+        refreshHere();
+    }
+
+    // Without a player there is nowhere to call "here", so the Here tab explains how to get one instead.
+    void showUntracked() {
+        untracked = true;
+        refreshHere();
+    }
+
+    void markSelected(BiomePalette palette) {
+        selectedPalette = palette;
+        updatingSelection = true;
+        try {
+            selectInHereList();
+            selectInTree();
+        } finally {
+            updatingSelection = false;
+        }
+    }
+
+    private JPanel buildTabBar() {
+        JPanel bar = new JPanel(new GridLayout(1, 2, 0, 0));
+        bar.setBorder(BorderFactory.createMatteBorder(0, 0, 1, 0, StudioTheme.SEPARATOR));
+        ButtonGroup group = new ButtonGroup();
+        JToggleButton here = createTab("Here", HERE_CARD, group);
+        JToggleButton overview = createTab("Overview", OVERVIEW_CARD, group);
+        bar.add(here);
+        bar.add(overview);
+        here.doClick();
+        return bar;
+    }
+
+    private JToggleButton createTab(String text, String card, ButtonGroup group) {
+        JToggleButton tab = StudioToolbar.tab(text);
+        tab.addActionListener(event -> cards.show(cardPanel, card));
+        group.add(tab);
+        return tab;
+    }
+
+    private JPanel buildHereCard() {
+        JPanel card = new JPanel(new BorderLayout());
+        JPanel location = new JPanel(new GridLayout(0, 1, 0, StudioTheme.scale(3)));
+        location.setBorder(StudioTheme.emptyBorder(9, 12, 5, 12));
+        location.add(regionLabel);
+
+        hereList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
+        hereList.setCellRenderer(new HereRowRenderer());
+        hereList.addListSelectionListener(event -> {
+            HereRow row = hereList.getSelectedValue();
+            if (!event.getValueIsAdjusting() && !updatingSelection && row != null && row.biomeKey() != null) {
+                choose(row.biomeKey(), row.palette());
+            }
+        });
+        card.add(location, BorderLayout.NORTH);
+        card.add(StudioToolbar.scroll(hereList), BorderLayout.CENTER);
+        return card;
+    }
+
+    private JPanel buildOverviewCard() {
+        JPanel card = new JPanel(new BorderLayout());
+        StudioToolbar.makeSearchField(searchField, "Search biomes, snippets or blocks...");
+        searchField.getDocument().addDocumentListener(new DocumentListener() {
+            @Override
+            public void insertUpdate(DocumentEvent event) {
+                rebuildOverview();
+            }
+
+            @Override
+            public void removeUpdate(DocumentEvent event) {
+                rebuildOverview();
+            }
+
+            @Override
+            public void changedUpdate(DocumentEvent event) {
+                rebuildOverview();
+            }
+        });
+
+        overviewTree.setRootVisible(false);
+        overviewTree.setShowsRootHandles(true);
+        overviewTree.setRowHeight(StudioTheme.scale(24));
+        overviewTree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
+        overviewTree.setCellRenderer(new OverviewRenderer());
+        overviewTree.addTreeSelectionListener(event -> {
+            if (!updatingSelection && nodeAt(event.getPath()) instanceof OverviewNode node && node.biomeKey() != null) {
+                choose(node.biomeKey(), node.palette());
+            }
+        });
+        card.add(StudioToolbar.padded(searchField, 8, 8, 8, 8), BorderLayout.NORTH);
+        card.add(StudioToolbar.scroll(overviewTree), BorderLayout.CENTER);
+        return card;
+    }
+
+    // Choosing a biome rather than one of its palettes opens its first palette.
+    private void choose(String biomeKey, BiomePalette palette) {
+        BiomeEntry biome = catalog == null ? null : catalog.biome(biomeKey);
+        BiomePalette chosen = palette != null ? palette : biome == null ? null : biome.firstPalette();
+        if (chosen != null) {
+            listener.onPaletteChosen(chosen);
+        }
+    }
+
+    private void refreshHere() {
+        updatingSelection = true;
+        try {
+            hereRows.clear();
+            if (untracked) {
+                showHereMessage("Run /iris std pal in-game to see the palettes where you stand.");
+                return;
+            }
+            if (location == null || catalog == null) {
+                showHereMessage("Finding where you are...");
+                return;
+            }
+            switch (location.status()) {
+                case OFFLINE -> showHereMessage("You are offline.");
+                case IN_OTHER_WORLD -> showHereMessage("You left the world this window shows.");
+                case IN_REGION -> showHereRows(location);
+            }
+            selectInHereList();
+        } finally {
+            updatingSelection = false;
+        }
+    }
+
+    private void showHereMessage(String message) {
+        regionLabel.setText("<html><body style='width:" + StudioTheme.scale(MESSAGE_WRAP_WIDTH_PIXELS) + "px'>" + message + "</body></html>");
+    }
+
+    private void showHereRows(PlayerLocation here) {
+        RegionEntry region = catalog.region(here.regionKey());
+        regionLabel.setText(labeled("Region", region == null ? here.regionKey() : region.name(), here.regionKey()));
+        addBiomePalettes("Surface biome here", here.surfaceBiomeKey());
+        if (here.isBelowSurfaceBiome()) {
+            addBiomePalettes("Underground biome at your height", here.biomeAtPositionKey());
+        }
+        if (region == null) {
+            return;
+        }
+        hereRows.addElement(HereRow.header("Biomes in this region"));
+        for (String biomeKey : region.allBiomeKeys()) {
+            addRegionBiome(biomeKey, 0, new HashSet<>(), here);
+        }
+    }
+
+    private void addBiomePalettes(String title, String biomeKey) {
+        BiomeEntry biome = catalog.biome(biomeKey);
+        if (biome == null) {
+            return;
+        }
+        hereRows.addElement(HereRow.header(title));
+        hereRows.addElement(HereRow.biome(biomeText(biome, childOfText(biome)), biomeKey, 0));
+        addPaletteRows(biome, 0);
+    }
+
+    private void addPaletteRows(BiomeEntry biome, int nesting) {
+        for (PaletteCatalog.PaletteSummary summary : biome.palettes()) {
+            hereRows.addElement(HereRow.palette(summary.text(), summary.palette(), nesting));
+        }
+    }
+
+    // Children sit under the biome they grow inside of, so a child biome is found where it actually appears.
+    private void addRegionBiome(String biomeKey, int nesting, Set<String> ancestors, PlayerLocation here) {
+        BiomeEntry biome = catalog.biome(biomeKey);
+        if (biome == null || !ancestors.add(biomeKey)) {
+            return;
+        }
+        boolean standingHere = biomeKey.equals(here.surfaceBiomeKey()) || biomeKey.equals(here.biomeAtPositionKey());
+        hereRows.addElement(HereRow.biome(biomeText(biome, standingHere ? "you are here" : null), biomeKey, nesting));
+        addPaletteRows(biome, nesting);
+        for (String childKey : biome.childKeys()) {
+            addRegionBiome(childKey, nesting + 1, new HashSet<>(ancestors), here);
+        }
+    }
+
+    private String childOfText(BiomeEntry biome) {
+        if (biome.parentKeys().isEmpty()) {
+            return null;
+        }
+        List<String> parentNames = biome.parentKeys().stream()
+                .map(key -> catalog.biome(key) == null ? key : catalog.biome(key).name())
+                .toList();
+        return "child of " + String.join(", ", parentNames);
+    }
+
+    private void rebuildOverview() {
+        if (catalog == null) {
+            return;
+        }
+        String filter = searchField.getText().trim().toLowerCase(Locale.ROOT);
+        DefaultMutableTreeNode root = new DefaultMutableTreeNode();
+        for (RegionEntry region : catalog.regions()) {
+            boolean regionMatches = !filter.isEmpty() && region.name().toLowerCase(Locale.ROOT).contains(filter);
+            DefaultMutableTreeNode regionNode = new DefaultMutableTreeNode(new OverviewNode(region.name(), region.key(), null, null));
+            for (BiomeGroup group : region.groups()) {
+                DefaultMutableTreeNode groupNode = new DefaultMutableTreeNode();
+                for (String biomeKey : group.biomeKeys()) {
+                    addBiomeNode(groupNode, biomeKey, regionMatches ? "" : filter, new HashSet<>());
+                }
+                if (groupNode.getChildCount() > 0) {
+                    groupNode.setUserObject(new OverviewNode(group.label(), groupNode.getChildCount() + " biomes", null, null));
+                    regionNode.add(groupNode);
+                }
+            }
+            if (regionNode.getChildCount() > 0) {
+                root.add(regionNode);
+            }
+        }
+        DefaultMutableTreeNode outside = new DefaultMutableTreeNode();
+        for (String biomeKey : catalog.biomesOutsideRegions()) {
+            addBiomeNode(outside, biomeKey, filter, new HashSet<>());
+        }
+        if (outside.getChildCount() > 0) {
+            outside.setUserObject(new OverviewNode("Not in any region", outside.getChildCount() + " biomes", null, null));
+            root.add(outside);
+        }
+        addSnippetNodes(root, filter);
+        updatingSelection = true;
+        try {
+            treeModel.setRoot(root);
+            if (!filter.isEmpty()) {
+                expandDownToBiomes(root);
+            }
+            selectInTree();
+        } finally {
+            updatingSelection = false;
+        }
+    }
+
+    private void addBiomeNode(DefaultMutableTreeNode parent, String biomeKey, String filter, Set<String> ancestors) {
+        BiomeEntry biome = catalog.biome(biomeKey);
+        if (biome == null || !ancestors.add(biomeKey)) {
+            return;
+        }
+        DefaultMutableTreeNode biomeNode = new DefaultMutableTreeNode(new OverviewNode(biome.name(), biomeKey, biomeKey, null));
+        for (PaletteCatalog.PaletteSummary summary : biome.palettes()) {
+            biomeNode.add(new DefaultMutableTreeNode(new OverviewNode(summary.text(), null, biomeKey, summary.palette())));
+        }
+        for (String childKey : biome.childKeys()) {
+            addBiomeNode(biomeNode, childKey, filter, new HashSet<>(ancestors));
+        }
+        boolean hasMatchingChild = biomeNode.getChildCount() > biome.palettes().size();
+        if (filter.isEmpty() || biome.matches(filter) || hasMatchingChild) {
+            parent.add(biomeNode);
+        }
+    }
+
+    // Snippets sit below the regions, so a palette picked elsewhere is still found in its biome first.
+    private void addSnippetNodes(DefaultMutableTreeNode root, String filter) {
+        for (BiomePalette.SnippetFolder folder : BiomePalette.SnippetFolder.values()) {
+            DefaultMutableTreeNode folderNode = new DefaultMutableTreeNode();
+            catalog.snippets().stream()
+                    .filter(snippet -> snippet.folder() == folder && (filter.isEmpty() || snippet.matches(filter)))
+                    .forEach(snippet -> folderNode.add(snippetNode(snippet)));
+            if (folderNode.getChildCount() > 0) {
+                folderNode.setUserObject(new OverviewNode(folder.label() + " snippets", folderNode.getChildCount() + " files", null, null));
+                root.add(folderNode);
+            }
+        }
+    }
+
+    // Picking a snippet opens it where the first biome using it places it; its children open the other uses.
+    private DefaultMutableTreeNode snippetNode(PaletteCatalog.SnippetEntry snippet) {
+        if (snippet.uses().isEmpty()) {
+            return new DefaultMutableTreeNode(new OverviewNode(snippet.path(), "not used by any biome", null, null));
+        }
+        BiomePalette firstUse = snippet.uses().get(0);
+        String usedBy = snippet.uses().size() == 1 ? "used once" : "used " + snippet.uses().size() + " times";
+        DefaultMutableTreeNode node = new DefaultMutableTreeNode(new OverviewNode(snippet.path() + " · " + snippet.blocks(),
+                usedBy, firstUse.biomeKey(), firstUse));
+        for (BiomePalette use : snippet.uses()) {
+            BiomeEntry biome = catalog.biome(use.biomeKey());
+            String biomeName = biome == null ? use.biomeKey() : biome.name();
+            node.add(new DefaultMutableTreeNode(new OverviewNode(biomeName + " · " + use.lowercaseLabel(), use.biomeKey(),
+                    use.biomeKey(), use)));
+        }
+        return node;
+    }
+
+    private void expandDownToBiomes(DefaultMutableTreeNode root) {
+        Enumeration<?> nodes = root.breadthFirstEnumeration();
+        while (nodes.hasMoreElements()) {
+            DefaultMutableTreeNode node = (DefaultMutableTreeNode) nodes.nextElement();
+            if (node.getUserObject() instanceof OverviewNode overview && overview.biomeKey() != null) {
+                overviewTree.expandPath(new TreePath(((DefaultMutableTreeNode) node.getParent()).getPath()));
+            }
+        }
+    }
+
+    private void selectInTree() {
+        if (selectedNodeShowsSelectedPalette()) {
+            return;
+        }
+        DefaultMutableTreeNode match = findLayerNode((DefaultMutableTreeNode) treeModel.getRoot());
+        if (match == null) {
+            overviewTree.clearSelection();
+            return;
+        }
+        TreePath path = new TreePath(match.getPath());
+        overviewTree.setSelectionPath(path);
+        overviewTree.makeVisible(path);
+        Rectangle row = overviewTree.getPathBounds(path);
+        if (row != null) {
+            overviewTree.scrollRectToVisible(new Rectangle(0, row.y, 1, row.height));
+        }
+    }
+
+    // The same palette can be listed under its biome and under its snippet; the row the user picked stays picked.
+    private boolean selectedNodeShowsSelectedPalette() {
+        return nodeAt(overviewTree.getSelectionPath()) instanceof OverviewNode node
+                && node.palette() != null
+                && node.palette().equals(selectedPalette);
+    }
+
+    private DefaultMutableTreeNode findLayerNode(DefaultMutableTreeNode root) {
+        Enumeration<?> nodes = root.depthFirstEnumeration();
+        while (nodes.hasMoreElements()) {
+            DefaultMutableTreeNode node = (DefaultMutableTreeNode) nodes.nextElement();
+            if (node.getUserObject() instanceof OverviewNode overview
+                    && overview.palette() != null
+                    && overview.palette().equals(selectedPalette)) {
+                return node;
+            }
+        }
+        return null;
+    }
+
+    private void selectInHereList() {
+        for (int index = 0; index < hereRows.size(); index++) {
+            HereRow row = hereRows.get(index);
+            if (row.palette() != null && row.palette().equals(selectedPalette)) {
+                hereList.setSelectedIndex(index);
+                return;
+            }
+        }
+        hereList.clearSelection();
+    }
+
+    private static Object nodeAt(TreePath path) {
+        return path == null ? null : ((DefaultMutableTreeNode) path.getLastPathComponent()).getUserObject();
+    }
+
+    private static String biomeText(BiomeEntry biome, String note) {
+        String noteText = note == null ? "" : " · " + escape(note);
+        return "<html>" + escape(biome.name()) + noteText + " <font color='" + StudioTheme.SECONDARY_TEXT.toHtml() + "'>" + escape(biome.key())
+                + "</font></html>";
+    }
+
+    private static String labeled(String title, String name, String key) {
+        return "<html><font color='" + StudioTheme.SECONDARY_TEXT.toHtml() + "'>" + title + "</font>&nbsp; " + escape(name)
+                + " <font color='" + StudioTheme.SECONDARY_TEXT.toHtml() + "'>" + escape(key) + "</font></html>";
+    }
+
+    private static String escape(String text) {
+        return text.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;");
+    }
+
+    interface Listener {
+        void onPaletteChosen(BiomePalette palette);
+    }
+
+    /**
+     * @param nesting how many parent biomes deep the row's biome sits
+     */
+    private record HereRow(String text, String biomeKey, BiomePalette palette, int nesting, boolean header) {
+        private static HereRow header(String text) {
+            return new HereRow(text, null, null, 0, true);
+        }
+
+        private static HereRow biome(String text, String biomeKey, int nesting) {
+            return new HereRow(text, biomeKey, null, nesting, false);
+        }
+
+        private static HereRow palette(String text, BiomePalette palette, int nesting) {
+            return new HereRow(text, palette.biomeKey(), palette, nesting, false);
+        }
+    }
+
+    private record OverviewNode(String label, String detail, String biomeKey, BiomePalette palette) {
+        private String html() {
+            if (detail == null) {
+                return escape(label);
+            }
+            return "<html>" + escape(label) + " <font color='" + StudioTheme.SECONDARY_TEXT.toHtml() + "'>" + escape(detail) + "</font></html>";
+        }
+    }
+
+    private static final class HereRowRenderer extends DefaultListCellRenderer {
+        private static final long serialVersionUID = 2785341117408251320L;
+        private static final int HEADER_INDENT = 11;
+        private static final int BIOME_INDENT = 20;
+        private static final int PALETTE_INDENT = 34;
+        private static final int CHILD_INDENT = 16;
+
+        @Override
+        public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean selected, boolean focus) {
+            HereRow row = (HereRow) value;
+            boolean selectable = row.biomeKey() != null;
+            super.getListCellRendererComponent(list, row.header() ? row.text().toUpperCase(Locale.ROOT) : row.text(), index,
+                    selected && selectable, false);
+            setFont(row.header() ? StudioTheme.sectionFont() : StudioTheme.font());
+            if (row.header()) {
+                setForeground(StudioTheme.MUTED_TEXT);
+            }
+            int indent = row.header() ? HEADER_INDENT
+                    : (row.palette() != null ? PALETTE_INDENT : BIOME_INDENT) + row.nesting() * CHILD_INDENT;
+            setBorder(StudioTheme.emptyBorder(row.header() ? 11 : 4, indent, 4, 10));
+            return this;
+        }
+    }
+
+    private static final class OverviewRenderer extends DefaultTreeCellRenderer {
+        private static final long serialVersionUID = -1950176034017718227L;
+
+        private OverviewRenderer() {
+            setLeafIcon(null);
+            setOpenIcon(null);
+            setClosedIcon(null);
+        }
+
+        @Override
+        public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded,
+                                                      boolean leaf, int row, boolean focus) {
+            Object userObject = ((DefaultMutableTreeNode) value).getUserObject();
+            String text = userObject instanceof OverviewNode node ? node.html() : "";
+            super.getTreeCellRendererComponent(tree, text, selected, expanded, leaf, row, false);
+            boolean groupsOthers = userObject instanceof OverviewNode node && node.biomeKey() == null && !leaf;
+            setFont(groupsOthers ? StudioTheme.boldFont() : StudioTheme.font());
+            return this;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PickInspectorPanel.java

@@ -0,0 +1,451 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.components.PickDisplay;
+
+import javax.swing.BorderFactory;
+import javax.swing.BoxLayout;
+import javax.swing.ButtonGroup;
+import javax.swing.JComponent;
+import javax.swing.JLabel;
+import javax.swing.Icon;
+import javax.swing.JPanel;
+import javax.swing.JScrollPane;
+import javax.swing.JTextArea;
+import javax.swing.JToggleButton;
+import javax.swing.Scrollable;
+import javax.swing.SwingConstants;
+import javax.swing.SwingUtilities;
+import javax.swing.UIManager;
+import javax.swing.text.DefaultCaret;
+import java.awt.BorderLayout;
+import java.awt.CardLayout;
+import java.awt.Color;
+import java.awt.Cursor;
+import java.awt.Dimension;
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.GridLayout;
+import java.awt.Rectangle;
+import java.awt.RenderingHints;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.util.ArrayList;
+import java.util.EnumMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.function.BooleanSupplier;
+import java.util.function.Consumer;
+
+/**
+ * The inspector of the region and biome views: how noise picks the regions or biomes in view, measured against what
+ * is in view and put in words, with a switch for how the map draws the picks. What the user opens or closes stays so
+ * while the view is measured again.
+ */
+final class PickInspectorPanel extends JPanel {
+    private static final long serialVersionUID = -2874105263188240317L;
+    private static final String MESSAGE_CARD = "message";
+    private static final String DETAILS_CARD = "details";
+    private static final int PANEL_WIDTH = 330;
+    private static final String PARAGRAPH_BREAK = "\n\n";
+
+    private final JLabel title = new JLabel();
+    private final JLabel detail = new JLabel();
+    private final Map<PickDisplay, JToggleButton> displayButtons = new EnumMap<>(PickDisplay.class);
+    private final CardLayout cards = new CardLayout();
+    private final JPanel cardPanel = new JPanel(cards);
+    private final JTextArea message = wrappingText();
+    private final JPanel details = new ViewportWidthPanel();
+    private final JScrollPane detailsScroll = StudioToolbar.scroll(details);
+    private final Set<String> expandedSectionKeys = new HashSet<>();
+    private final Set<String> fullTableKeys = new HashSet<>();
+    private final String picksName;
+    private boolean sectionsChosenByUser;
+    private String shownDetailsTitle;
+
+    /**
+     * @param picksName       what the map shows when it draws the picks: "Regions" or "Biomes"
+     * @param onDisplayChosen receives how the map should draw the picks
+     */
+    PickInspectorPanel(String picksName, Consumer<PickDisplay> onDisplayChosen) {
+        super(new BorderLayout());
+        this.picksName = picksName;
+        setPreferredSize(StudioTheme.scaledSize(PANEL_WIDTH, 0));
+        setBackground(StudioTheme.PANEL_BACKGROUND);
+        add(buildHeader(onDisplayChosen), BorderLayout.NORTH);
+        cardPanel.setOpaque(false);
+        cardPanel.add(buildMessageCard(), MESSAGE_CARD);
+        details.setLayout(new BoxLayout(details, BoxLayout.Y_AXIS));
+        details.setBackground(StudioTheme.PANEL_BACKGROUND);
+        cardPanel.add(detailsScroll, DETAILS_CARD);
+        add(cardPanel, BorderLayout.CENTER);
+        showMeasuring(picksName);
+    }
+
+    void selectDisplay(PickDisplay display) {
+        displayButtons.get(display).setSelected(true);
+    }
+
+    void showMeasuring(String name) {
+        showHeader(name, "Measuring what is in view…");
+        showMessage("");
+    }
+
+    void showRegionPicks(NoisePickSpread spread, List<String> notes) {
+        showHeader("Regions", "Region noise, split by rarity");
+        nameFirstDisplay("Regions");
+        showDetails(List.of(noiseChart(spread, "Regions", "regions")), notes);
+    }
+
+    void showBiomePicks(String regionName, List<NoisePickSpread> spreads, List<String> notes) {
+        showHeader(regionName, "Biome terrain · biome noise, split by rarity");
+        nameFirstDisplay("Biomes");
+        showDetails(spreads.stream().map(spread -> (JComponent) noiseChart(spread, "Biomes", spread.title())).toList(), notes);
+    }
+
+    void showCoverage(String regionName, RegionHeightCoverage coverage, List<String> notes) {
+        showHeader(regionName, "Hybrid terrain · biomes by height");
+        nameFirstDisplay("Biomes");
+        showDetails(List.of(heightChart(coverage)), notes);
+    }
+
+    /**
+     * One collapsible section per region in view, each with how it picks its biomes, then notes about all of them.
+     * Until the user opens or closes one, only the first is open.
+     */
+    void showRegionSections(String detailText, List<Section> sections, List<String> notes) {
+        showHeader(picksName, detailText);
+        nameFirstDisplay(picksName);
+        if (!sectionsChosenByUser) {
+            expandedSectionKeys.clear();
+            sections.stream().findFirst().ifPresent(first -> expandedSectionKeys.add(first.key()));
+        }
+        List<JComponent> components = new ArrayList<>();
+        for (Section section : sections) {
+            components.add(new SectionPanel(section, expandedSectionKeys.contains(section.key())));
+        }
+        showDetails(components, notes);
+    }
+
+    /**
+     * A chart whose long table remembers, by this key, whether the user asked for all its rows.
+     */
+    NoisePickChart noiseChart(NoisePickSpread spread, String optionNoun, String key) {
+        return new NoisePickChart(spread, optionNoun, fullTableKeys.contains(key), showsAll -> {
+            if (showsAll) {
+                fullTableKeys.add(key);
+            } else {
+                fullTableKeys.remove(key);
+            }
+        });
+    }
+
+    static RegionHeightChart heightChart(RegionHeightCoverage coverage) {
+        RegionHeightChart chart = new RegionHeightChart();
+        chart.setAlignmentX(LEFT_ALIGNMENT);
+        chart.show(coverage);
+        return chart;
+    }
+
+    private JPanel buildHeader(Consumer<PickDisplay> onDisplayChosen) {
+        JPanel header = new JPanel(new GridLayout(0, 1, 0, StudioTheme.scale(6)));
+        header.setOpaque(false);
+        header.setBorder(BorderFactory.createCompoundBorder(
+                BorderFactory.createMatteBorder(0, 0, 1, 0, StudioTheme.SEPARATOR),
+                StudioTheme.emptyBorder(10, 16, 12, 16)));
+        title.setFont(StudioTheme.titleFont());
+        detail.setFont(StudioTheme.smallFont());
+        detail.setForeground(StudioTheme.MUTED_TEXT);
+        header.add(title);
+        header.add(detail);
+        header.add(sectionLabel("Show"));
+        header.add(buildDisplayButtons(onDisplayChosen));
+        return header;
+    }
+
+    private JPanel buildDisplayButtons(Consumer<PickDisplay> onDisplayChosen) {
+        JPanel row = new JPanel(new GridLayout(1, 0, StudioTheme.scale(4), 0));
+        row.setOpaque(false);
+        ButtonGroup group = new ButtonGroup();
+        for (PickDisplay display : PickDisplay.values()) {
+            JToggleButton button = new JToggleButton(displayName(display));
+            button.setFocusable(false);
+            button.setSelected(display == PickDisplay.PICKS);
+            button.addActionListener(event -> onDisplayChosen.accept(display));
+            group.add(button);
+            row.add(button);
+            displayButtons.put(display, button);
+        }
+        return row;
+    }
+
+    private String displayName(PickDisplay display) {
+        return switch (display) {
+            case PICKS -> picksName;
+            case NOISE -> "Noise";
+            case BOTH -> "Both";
+        };
+    }
+
+    private void nameFirstDisplay(String name) {
+        displayButtons.get(PickDisplay.PICKS).setText(name);
+    }
+
+    private JPanel buildMessageCard() {
+        JPanel card = new JPanel(new BorderLayout());
+        card.setOpaque(false);
+        message.setBorder(StudioTheme.emptyBorder(12, 16, 12, 16));
+        card.add(message, BorderLayout.NORTH);
+        return card;
+    }
+
+    private void showHeader(String name, String detailText) {
+        title.setText(name);
+        detail.setText(detailText);
+    }
+
+    private void rememberSectionExpanded(String key, boolean expanded) {
+        sectionsChosenByUser = true;
+        if (expanded) {
+            expandedSectionKeys.add(key);
+        } else {
+            expandedSectionKeys.remove(key);
+        }
+    }
+
+    private void showMessage(String text) {
+        message.setText(text);
+        cards.show(cardPanel, MESSAGE_CARD);
+    }
+
+    // Measuring the same subject again keeps the scroll position, so panning the map doesn't jump the list.
+    private void showDetails(List<JComponent> charts, List<String> notes) {
+        boolean sameSubject = Objects.equals(title.getText(), shownDetailsTitle);
+        int scrollPosition = sameSubject ? detailsScroll.getVerticalScrollBar().getValue() : 0;
+        shownDetailsTitle = title.getText();
+        details.removeAll();
+        charts.forEach(details::add);
+        if (!notes.isEmpty()) {
+            details.add(notesText(notes));
+        }
+        details.revalidate();
+        details.repaint();
+        cards.show(cardPanel, DETAILS_CARD);
+        SwingUtilities.invokeLater(() -> detailsScroll.getVerticalScrollBar().setValue(scrollPosition));
+    }
+
+    private static JTextArea notesText(List<String> notes) {
+        JTextArea text = wrappingText();
+        text.setAlignmentX(LEFT_ALIGNMENT);
+        text.setBorder(StudioTheme.emptyBorder(4, 16, 12, 16));
+        text.setText(String.join(PARAGRAPH_BREAK, notes));
+        return text;
+    }
+
+    private static JLabel sectionLabel(String text) {
+        JLabel label = new JLabel(text.toUpperCase(Locale.ROOT));
+        label.setForeground(StudioTheme.MUTED_TEXT);
+        label.setFont(StudioTheme.sectionFont());
+        return label;
+    }
+
+    private static JTextArea wrappingText() {
+        JTextArea text = new JTextArea();
+        text.setEditable(false);
+        text.setFocusable(false);
+        text.setOpaque(false);
+        ((DefaultCaret) text.getCaret()).setUpdatePolicy(DefaultCaret.NEVER_UPDATE);
+        text.setLineWrap(true);
+        text.setWrapStyleWord(true);
+        text.setFont(StudioTheme.font());
+        text.setForeground(StudioTheme.SECONDARY_TEXT);
+        return text;
+    }
+
+    /**
+     * One region of the biome view's inspector.
+     *
+     * @param share   how much of the view the region covers
+     * @param summary what the closed section says about its content, like "7 biomes"
+     */
+    record Section(String key, String name, int color, double share, String summary, List<JComponent> charts,
+                   List<String> notes) {
+    }
+
+    /**
+     * A region's header, which opens and closes the charts and notes below it.
+     */
+    private final class SectionPanel extends JPanel {
+        private static final long serialVersionUID = 2318546098861530717L;
+
+        private final JPanel body = new JPanel();
+
+        private SectionPanel(Section section, boolean expanded) {
+            setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
+            setOpaque(false);
+            setAlignmentX(LEFT_ALIGNMENT);
+            body.setLayout(new BoxLayout(body, BoxLayout.Y_AXIS));
+            body.setOpaque(false);
+            body.setAlignmentX(LEFT_ALIGNMENT);
+            section.charts().forEach(body::add);
+            if (!section.notes().isEmpty()) {
+                body.add(notesText(section.notes()));
+            }
+            body.setVisible(expanded);
+            add(new SectionHeader(section, body::isVisible, () -> toggle(section)));
+            add(body);
+        }
+
+        private void toggle(Section section) {
+            body.setVisible(!body.isVisible());
+            rememberSectionExpanded(section.key(), body.isVisible());
+            revalidate();
+            repaint();
+        }
+    }
+
+    /**
+     * A region's name in its colour behind an open or closed chevron, with what it holds and how much of the view it
+     * covers; clicking it opens or closes the region.
+     */
+    private static final class SectionHeader extends JComponent {
+        private static final long serialVersionUID = -4730226930154581123L;
+        private static final int HEIGHT = 32;
+        private static final int MARGIN = 16;
+        private static final int CHEVRON_WIDTH = 16;
+        private static final int SWATCH_SIZE = 12;
+        private static final int SWATCH_GAP = 8;
+        private static final int SUMMARY_GAP = 8;
+
+        private final Section section;
+        private final BooleanSupplier expanded;
+
+        private SectionHeader(Section section, BooleanSupplier expanded, Runnable onToggle) {
+            this.section = section;
+            this.expanded = expanded;
+            setAlignmentX(LEFT_ALIGNMENT);
+            setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
+            addMouseListener(new MouseAdapter() {
+                @Override
+                public void mouseClicked(MouseEvent event) {
+                    onToggle.run();
+                    repaint();
+                }
+            });
+        }
+
+        @Override
+        public Dimension getPreferredSize() {
+            return StudioTheme.scaledSize(PANEL_WIDTH, HEIGHT);
+        }
+
+        @Override
+        public Dimension getMaximumSize() {
+            return new Dimension(Integer.MAX_VALUE, getPreferredSize().height);
+        }
+
+        @Override
+        protected void paintComponent(Graphics graphics) {
+            Graphics2D canvas = (Graphics2D) graphics.create();
+            try {
+                canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+                canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+                canvas.setColor(StudioTheme.SEPARATOR);
+                canvas.fillRect(0, 0, getWidth(), 1);
+                int left = StudioTheme.scale(MARGIN) - StudioTheme.scale(4);
+                paintChevron(canvas, left);
+                left += StudioTheme.scale(CHEVRON_WIDTH);
+                int swatch = StudioTheme.scale(SWATCH_SIZE);
+                canvas.setColor(new Color(section.color()));
+                int arc = StudioTheme.scale(4);
+                canvas.fillRoundRect(left, (getHeight() - swatch) / 2, swatch, swatch, arc, arc);
+                left += swatch + StudioTheme.scale(SWATCH_GAP);
+
+                canvas.setFont(StudioTheme.smallFont());
+                FontMetrics small = canvas.getFontMetrics();
+                String share = NoisePickChart.percent(section.share());
+                int shareLeft = getWidth() - StudioTheme.scale(MARGIN) - small.stringWidth(share);
+                canvas.setFont(StudioTheme.boldFont());
+                FontMetrics bold = canvas.getFontMetrics();
+                int baseline = (getHeight() + bold.getAscent() - bold.getDescent()) / 2;
+                canvas.setColor(StudioTheme.TEXT);
+                canvas.drawString(section.name(), left, baseline);
+                left += bold.stringWidth(section.name()) + StudioTheme.scale(SUMMARY_GAP);
+
+                canvas.setFont(StudioTheme.smallFont());
+                canvas.setColor(StudioTheme.MUTED_TEXT);
+                if (section.summary() != null && left + small.stringWidth(section.summary()) < shareLeft - StudioTheme.scale(SUMMARY_GAP)) {
+                    canvas.drawString(section.summary(), left, baseline);
+                }
+                canvas.setColor(StudioTheme.SECONDARY_TEXT);
+                canvas.drawString(share, shareLeft, baseline);
+            } finally {
+                canvas.dispose();
+            }
+        }
+
+        private void paintChevron(Graphics2D canvas, int left) {
+            Icon chevron = UIManager.getIcon(expanded.getAsBoolean() ? "Tree.expandedIcon" : "Tree.collapsedIcon");
+            if (chevron == null) {
+                return;
+            }
+            chevron.paintIcon(this, canvas, left + (StudioTheme.scale(CHEVRON_WIDTH) - chevron.getIconWidth()) / 2,
+                    (getHeight() - chevron.getIconHeight()) / 2);
+        }
+    }
+
+    /**
+     * Follows the scroll pane's width, so the charts stretch to it and the notes wrap inside it.
+     */
+    private static final class ViewportWidthPanel extends JPanel implements Scrollable {
+        private static final long serialVersionUID = 6086542174870301352L;
+        private static final int SCROLL_STEP = 18;
+
+        @Override
+        public Dimension getPreferredScrollableViewportSize() {
+            return getPreferredSize();
+        }
+
+        @Override
+        public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
+            return StudioTheme.scale(SCROLL_STEP);
+        }
+
+        @Override
+        public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
+            return orientation == SwingConstants.VERTICAL ? visibleRect.height : visibleRect.width;
+        }
+
+        @Override
+        public boolean getScrollableTracksViewportWidth() {
+            return true;
+        }
+
+        @Override
+        public boolean getScrollableTracksViewportHeight() {
+            return false;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PickMeasuring.java

@@ -0,0 +1,186 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.NoisePickSpread.Option;
+import com.volmit.iris.core.gui.RegionHeightCoverage.BiomeRange;
+import com.volmit.iris.core.gui.components.RenderType;
+import com.volmit.iris.engine.IrisComplex;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.InferredType;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisRegion;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * Samples the map in view to measure how regions and biomes are picked, and puts what stands out in words; shared by
+ * the region and biome views.
+ */
+final class PickMeasuring {
+    static final List<InferredType> PLACED_TYPES = List.of(InferredType.LAND, InferredType.SHORE, InferredType.SEA);
+    private static final int SAMPLES_PER_SIDE = 96;
+    private static final int NAMED_IN_NOTES = 3;
+
+    private PickMeasuring() {
+    }
+
+    static void forEachSample(MapCensus.ViewArea area, SampleVisitor visitor) {
+        double stepX = (area.maximumX() - area.minimumX()) / SAMPLES_PER_SIDE;
+        double stepZ = (area.maximumZ() - area.minimumZ()) / SAMPLES_PER_SIDE;
+        for (int row = 0; row < SAMPLES_PER_SIDE; row++) {
+            for (int column = 0; column < SAMPLES_PER_SIDE; column++) {
+                visitor.visit(area.minimumX() + (column + 0.5D) * stepX, area.minimumZ() + (row + 0.5D) * stepZ);
+            }
+        }
+    }
+
+    static Option regionOption(Engine engine, IrisRegion region) {
+        return new Option(region.getLoadKey(), region.getName(), regionColor(engine, region), region.getRarity());
+    }
+
+    static Option biomeOption(Engine engine, IrisBiome biome) {
+        return new Option(biome.getLoadKey(), biome.getName(), biome.getColor(engine, RenderType.BIOME).getRGB() & 0xFFFFFF,
+                biome.getRarity());
+    }
+
+    static int regionColor(Engine engine, IrisRegion region) {
+        return region.getColor(engine.getComplex(), RenderType.REGION).getRGB() & 0xFFFFFF;
+    }
+
+    /**
+     * One spread per biome list of the region that has biomes, in land, shore, sea order.
+     */
+    static List<TypedSpread> biomeSpreads(Engine engine, IrisComplex complex, IrisRegion region) {
+        List<TypedSpread> spreads = new ArrayList<>();
+        for (InferredType type : PLACED_TYPES) {
+            List<Option> options = complex.noisePickedBiomes(region, type).stream()
+                    .map(biome -> biomeOption(engine, biome))
+                    .toList();
+            if (!options.isEmpty()) {
+                spreads.add(new TypedSpread(type,
+                        NoisePickSpread.of(typeName(type) + " biome noise in view", options, complex.isLegacyRarity())));
+            }
+        }
+        return spreads;
+    }
+
+    static List<BiomeRange> biomeRanges(Engine engine, IrisRegion region) {
+        List<BiomeRange> ranges = new ArrayList<>();
+        for (InferredType type : PLACED_TYPES) {
+            for (IrisBiome biome : region.getBiomes(engine.getComplex(), type)) {
+                if (biome == null) {
+                    continue;
+                }
+                ranges.add(new BiomeRange(biome.getLoadKey(), biome.getName(),
+                        biome.getColor(engine, RenderType.BIOME).getRGB() & 0xFFFFFF, type,
+                        biome.getPlacement().getMinHeight(), biome.getPlacement().getMaxHeight()));
+            }
+        }
+        return ranges;
+    }
+
+    static void addSpreadNotes(List<String> notes, NoisePickSpread spread, String noun) {
+        List<NoisePickSpread.Row> rows = spread.rows();
+        if (spread.sampleCount() == 0) {
+            notes.add("No " + noun + " is picked in view.");
+            return;
+        }
+        if (rows.size() == 1) {
+            return;
+        }
+        if (spread.belowZeroShare() > 0D) {
+            notes.add(NoisePickChart.percent(spread.belowZeroShare()) + " of the " + noun + " noise in view is below 0, so "
+                    + rows.getFirst().option().name() + " gets it.");
+        }
+        if (spread.aboveOneShare() > 0D) {
+            notes.add(NoisePickChart.percent(spread.aboveOneShare()) + " of the " + noun + " noise in view is above 1, so "
+                    + rows.getLast().option().name() + " gets it.");
+        }
+        List<String> starved = rows.stream().filter(NoisePickSpread.Row::isFarBelowWeight).map(row -> row.option().name()).toList();
+        if (!starved.isEmpty()) {
+            boolean single = starved.size() == 1;
+            notes.add(namedFew(starved) + (single ? " gets" : " get") + " under half " + (single ? "its" : "their")
+                    + " weight in view (▼): the " + noun + " noise rarely reaches " + (single ? "its band." : "their bands."));
+        }
+    }
+
+    static void addBiomeSpreadNotes(List<String> notes, List<TypedSpread> spreads) {
+        for (TypedSpread typed : spreads) {
+            addSpreadNotes(notes, typed.spread(), typeName(typed.type()).toLowerCase(Locale.ROOT) + " biome");
+        }
+    }
+
+    static void addChildBiomeNote(List<String> notes, IrisComplex complex, IrisRegion region) {
+        List<String> parents = PLACED_TYPES.stream()
+                .flatMap(type -> complex.noisePickedBiomes(region, type).stream())
+                .filter(biome -> !biome.getChildren().isEmpty())
+                .map(IrisBiome::getName)
+                .distinct()
+                .toList();
+        if (!parents.isEmpty()) {
+            notes.add(namedFew(parents) + " then hand some spots to child biomes by a noise of their own.");
+        }
+    }
+
+    static void addRarityNotes(List<String> notes, IrisComplex complex, Collection<NoisePickSpread> spreads) {
+        if (spreads.stream().allMatch(spread -> spread.bands().size() <= 1)) {
+            return;
+        }
+        notes.add(complex.isLegacyRarity()
+                ? "Legacy rarity: each weight is the total rarity minus the option's own."
+                : "Each weight is one over the rarity, so rarity 2 gets half the noise of rarity 1.");
+    }
+
+    // A long list of names buries the point of a note, so only the first few are named.
+    private static String namedFew(List<String> names) {
+        if (names.size() <= NAMED_IN_NOTES) {
+            return String.join(", ", names);
+        }
+        return String.join(", ", names.subList(0, NAMED_IN_NOTES)) + " and " + (names.size() - NAMED_IN_NOTES) + " more";
+    }
+
+    static String measuredNote() {
+        return "Measured on a " + SAMPLES_PER_SIDE + " × " + SAMPLES_PER_SIDE + " grid over the map in view.";
+    }
+
+    static String hybridNoiseNote() {
+        return "Noise shows the height biomes are picked at: the overlay noise plus the dimension's biome placement "
+                + "jitter. Where ranges share a height, each biome's competition noise, divided by its rarity, decides.";
+    }
+
+    static String typeName(InferredType type) {
+        String name = type.name().toLowerCase(Locale.ROOT);
+        return Character.toUpperCase(name.charAt(0)) + name.substring(1);
+    }
+
+    @FunctionalInterface
+    interface SampleVisitor {
+        void visit(double x, double z);
+    }
+
+    /**
+     * The spread of the noise that picks from one of a region's biome lists.
+     */
+    record TypedSpread(InferredType type, NoisePickSpread spread) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PlayerLocationTracker.java

@@ -0,0 +1,124 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.tools.IrisToolbelt;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisRegion;
+import com.volmit.iris.engine.platform.PlatformChunkGenerator;
+import org.bukkit.Bukkit;
+import org.bukkit.Location;
+import org.bukkit.entity.Player;
+import org.bukkit.scheduler.BukkitTask;
+
+import java.awt.EventQueue;
+import java.util.UUID;
+
+final class PlayerLocationTracker {
+    private static final long CHECK_INTERVAL_TICKS = 10L;
+
+    private final UUID playerId;
+    private final UUID worldId;
+    private final Listener listener;
+    private BukkitTask task;
+    private PlayerLocation lastLocation;
+
+    private PlayerLocationTracker(UUID playerId, UUID worldId, Listener listener) {
+        this.playerId = playerId;
+        this.worldId = worldId;
+        this.listener = listener;
+    }
+
+    static PlayerLocationTracker follow(UUID playerId, UUID worldId, Listener listener) {
+        PlayerLocationTracker tracker = new PlayerLocationTracker(playerId, worldId, listener);
+        tracker.task = Bukkit.getScheduler().runTaskTimer(Iris.instance, tracker::checkLocation, 0L, CHECK_INTERVAL_TICKS);
+        return tracker;
+    }
+
+    void stop() {
+        if (task != null) {
+            task.cancel();
+        }
+    }
+
+    private void checkLocation() {
+        PlayerLocation location = locate();
+        if (location.equals(lastLocation)) {
+            return;
+        }
+        lastLocation = location;
+        EventQueue.invokeLater(() -> listener.onLocationChanged(location));
+    }
+
+    private PlayerLocation locate() {
+        Player player = Bukkit.getPlayer(playerId);
+        if (player == null) {
+            return PlayerLocation.OFFLINE;
+        }
+        if (player.getWorld() == null || !player.getWorld().getUID().equals(worldId)) {
+            return PlayerLocation.IN_OTHER_WORLD;
+        }
+        Engine engine = engineAt(player.getLocation());
+        if (engine == null) {
+            return PlayerLocation.IN_OTHER_WORLD;
+        }
+        Location position = player.getLocation();
+        IrisRegion region = engine.getRegion(position);
+        String surfaceBiome = keyOf(engine.getSurfaceBiome(position.getBlockX(), position.getBlockZ()));
+        String biomeAtPosition = keyOf(engine.getBiomeOrMantle(position));
+        if (region == null || region.getLoadKey() == null || surfaceBiome == null) {
+            return PlayerLocation.IN_OTHER_WORLD;
+        }
+        return new PlayerLocation(Status.IN_REGION, region.getLoadKey(), surfaceBiome, biomeAtPosition);
+    }
+
+    private static String keyOf(IrisBiome biome) {
+        return biome == null ? null : biome.getLoadKey();
+    }
+
+    private static Engine engineAt(Location location) {
+        if (location.getWorld() == null || !IrisToolbelt.isIrisWorld(location.getWorld())) {
+            return null;
+        }
+        PlatformChunkGenerator generator = IrisToolbelt.access(location.getWorld());
+        return generator == null ? null : generator.getEngine();
+    }
+
+    enum Status {
+        OFFLINE,
+        IN_OTHER_WORLD,
+        IN_REGION
+    }
+
+    // Biomes are 3D: underground, the biome at the player's position can differ from the surface biome above it.
+    record PlayerLocation(Status status, String regionKey, String surfaceBiomeKey, String biomeAtPositionKey) {
+        static final PlayerLocation OFFLINE = new PlayerLocation(Status.OFFLINE, null, null, null);
+        static final PlayerLocation IN_OTHER_WORLD = new PlayerLocation(Status.IN_OTHER_WORLD, null, null, null);
+
+        boolean isBelowSurfaceBiome() {
+            return biomeAtPositionKey != null && !biomeAtPositionKey.equals(surfaceBiomeKey);
+        }
+    }
+
+    interface Listener {
+        void onLocationChanged(PlayerLocation location);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/PregeneratorJob.java

@@ -212,7 +212,7 @@ public class PregeneratorJob implements PregenListener {
     public void open() {
         J.a(() -> {
             try {
-                frame = new JFrame("Pregen View");
+                frame = GuiHost.createFrame("Pregen View");
                 renderer = new PregenRenderer();
                 frame.addKeyListener(renderer);
                 renderer.l = new ReentrantLock();

core/src/main/java/com/volmit/iris/core/gui/ProceduralObjectSource.java

@@ -0,0 +1,92 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.loader.IrisData;
+import com.volmit.iris.engine.object.IrisObject;
+import com.volmit.iris.engine.object.procedural.ProceduralObjectCatalog;
+import com.volmit.iris.engine.object.procedural.ResolvedProceduralPlacement;
+
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.OptionalLong;
+
+/**
+ * The objects the pack's procedural settings generate, one entry per definition, in the folders the pack keeps them in.
+ */
+final class ProceduralObjectSource implements ObjectSource {
+    private static final Map<String, String> FOLDER_LABEL_BY_KIND = Map.of(
+            "trees", "Trees",
+            "formations", "Formations",
+            "crystals", "Crystals",
+            "coral", "Coral",
+            "fungi", "Fungi",
+            "ruins", "Ruins");
+
+    private static final int EMPTY_ICON_SIZE = 40;
+
+    private Map<String, ResolvedProceduralPlacement> definitionsByKey = Map.of();
+
+    @Override
+    public String noun() {
+        return "procedural object";
+    }
+
+    @Override
+    public EmptyState emptyState() {
+        return new EmptyState(MapViewIcon.large(MapView.PROCEDURAL, EMPTY_ICON_SIZE), "No procedural objects yet",
+                "Declare them in a biome or region, or save a settings file per object, like",
+                "snippet/" + ProceduralObjectCatalog.TREE_FOLDER + "/oak.json", "They appear here once the pack reloads.");
+    }
+
+    // The type folder gets its label; the rest of the path stays as the pack has it.
+    @Override
+    public List<String> keys(IrisData data) {
+        Map<String, ResolvedProceduralPlacement> byKey = new LinkedHashMap<>();
+        for (ProceduralObjectCatalog.Definition definition : data.getProceduralObjects().definitions()) {
+            String kind = definition.placement().kind();
+            String key = FOLDER_LABEL_BY_KIND.getOrDefault(kind, kind) + definition.path().substring(kind.length());
+            byKey.put(key, definition.placement());
+        }
+        definitionsByKey = byKey;
+        return List.copyOf(byKey.keySet());
+    }
+
+    @Override
+    public List<IrisObject> variants(IrisData data, String key) {
+        ResolvedProceduralPlacement definition = definitionsByKey.get(key);
+        return definition == null ? List.of() : definition.variants();
+    }
+
+    @Override
+    public OptionalLong seed(String key) {
+        ResolvedProceduralPlacement definition = definitionsByKey.get(key);
+        return definition == null ? OptionalLong.empty() : OptionalLong.of(definition.seed());
+    }
+
+    // The pack's own seed reuses the variants world generation bakes.
+    @Override
+    public List<IrisObject> variants(IrisData data, String key, long seed) {
+        ResolvedProceduralPlacement definition = definitionsByKey.get(key);
+        if (definition == null) {
+            return List.of();
+        }
+        return definition.seed() == seed ? definition.variants() : data.getProceduralObjects().reseeded(definition, seed).variants();
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/RegionExplorer.java

@@ -0,0 +1,212 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.PickMeasuring.TypedSpread;
+import com.volmit.iris.core.gui.RegionNavigator.RegionRow;
+import com.volmit.iris.core.gui.components.PickDisplay;
+import com.volmit.iris.engine.IrisComplex;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.InferredType;
+import com.volmit.iris.engine.object.IrisRegion;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+/**
+ * The region view's explorer: shows how the region noise picks the regions, and for a chosen region fills the map with
+ * its biomes and shows how they are picked, measured against what is in view.
+ */
+final class RegionExplorer {
+    private final Supplier<Engine> engineSource;
+    private final Consumer<String> onPreviewChanged;
+    private final RegionNavigator navigator = new RegionNavigator(this::choose);
+    private final PickInspectorPanel inspector;
+    private final LatestMeasurement<Measurement> measurer = new LatestMeasurement<>("Iris Region Explorer");
+    private String chosenRegionKey;
+    private MapCensus.ViewArea latestArea;
+    private MapCensus.ViewArea measuredArea;
+
+    /**
+     * @param onPreviewChanged receives the region to fill the map with, or null to show every region again
+     * @param onDisplayChosen  receives how the map should draw the picks
+     */
+    RegionExplorer(Supplier<Engine> engineSource, Consumer<String> onPreviewChanged, Consumer<PickDisplay> onDisplayChosen) {
+        this.engineSource = engineSource;
+        this.onPreviewChanged = onPreviewChanged;
+        this.inspector = new PickInspectorPanel("Regions", onDisplayChosen);
+    }
+
+    RegionNavigator navigator() {
+        return navigator;
+    }
+
+    PickInspectorPanel inspector() {
+        return inspector;
+    }
+
+    void loadRegions() {
+        Engine engine = engineSource.get();
+        if (engine == null || engine.getComplex() == null) {
+            return;
+        }
+        List<RegionRow> rows = new ArrayList<>();
+        for (IrisRegion region : engine.getComplex().noisePickedRegions()) {
+            rows.add(new RegionRow(region.getLoadKey(), region.getName(), PickMeasuring.regionColor(engine, region)));
+        }
+        navigator.showRegions(rows);
+    }
+
+    /**
+     * Measures the regions, or the chosen region's biomes, against this area, unless that was already done.
+     */
+    void measure(MapCensus.ViewArea area) {
+        latestArea = area;
+        if (area == null || area.equals(measuredArea)) {
+            return;
+        }
+        measuredArea = area;
+        String regionKey = chosenRegionKey;
+        measurer.measure(() -> measurePicks(regionKey, area), this::show);
+    }
+
+    /**
+     * The pack changed, so the regions and their biomes are read again.
+     */
+    void refresh() {
+        loadRegions();
+        measuredArea = null;
+        measure(latestArea);
+    }
+
+    void close() {
+        measurer.close();
+    }
+
+    private void choose(String regionKey) {
+        chosenRegionKey = regionKey;
+        measuredArea = null;
+        measurer.discardPending();
+        onPreviewChanged.accept(regionKey);
+        inspector.showMeasuring(regionKey == null ? "Regions" : regionName(regionKey));
+        measure(latestArea);
+    }
+
+    private String regionName(String regionKey) {
+        Engine engine = engineSource.get();
+        IrisRegion region = engine == null ? null : engine.getData().getRegionLoader().load(regionKey);
+        return region == null ? regionKey : region.getName();
+    }
+
+    private void show(Measurement measurement) {
+        if (!Objects.equals(measurement.regionKey(), chosenRegionKey)) {
+            return;
+        }
+        switch (measurement) {
+            case RegionPicks picks -> inspector.showRegionPicks(picks.spread(), picks.notes());
+            case BiomePicks picks -> inspector.showBiomePicks(picks.regionName(), picks.spreads(), picks.notes());
+            case HeightPicks picks -> inspector.showCoverage(picks.regionName(), picks.coverage(), picks.notes());
+        }
+    }
+
+    private Measurement measurePicks(String regionKey, MapCensus.ViewArea area) {
+        Engine engine = engineSource.get();
+        IrisComplex complex = engine == null ? null : engine.getComplex();
+        if (complex == null) {
+            return null;
+        }
+        if (regionKey == null) {
+            return measureRegionPicks(engine, complex, area);
+        }
+        IrisRegion region = engine.getData().getRegionLoader().load(regionKey);
+        if (region == null) {
+            return null;
+        }
+        return complex.isHybridTerrain()
+                ? measureHeightPicks(engine, complex, region, area)
+                : measureBiomePicks(engine, complex, region, area);
+    }
+
+    private static RegionPicks measureRegionPicks(Engine engine, IrisComplex complex, MapCensus.ViewArea area) {
+        List<NoisePickSpread.Option> options = complex.noisePickedRegions().stream()
+                .map(region -> PickMeasuring.regionOption(engine, region))
+                .toList();
+        NoisePickSpread spread = NoisePickSpread.of("Region noise in view", options, complex.isLegacyRarity());
+        PickMeasuring.forEachSample(area, (x, z) -> spread.add(complex.getRegionStyleStream().get(x, z)));
+        List<String> notes = new ArrayList<>();
+        PickMeasuring.addSpreadNotes(notes, spread, "region");
+        PickMeasuring.addRarityNotes(notes, complex, List.of(spread));
+        notes.add(PickMeasuring.measuredNote());
+        return new RegionPicks(spread, notes);
+    }
+
+    // The preview treats every spot as part of the region, so each spot's biome list is the one its surface needs.
+    private static BiomePicks measureBiomePicks(Engine engine, IrisComplex complex, IrisRegion region, MapCensus.ViewArea area) {
+        List<TypedSpread> spreads = PickMeasuring.biomeSpreads(engine, complex, region);
+        PickMeasuring.forEachSample(area, (x, z) -> {
+            InferredType type = complex.surfacePickAsIfIn(region, x, z).type();
+            spreads.stream()
+                    .filter(typed -> typed.type() == type)
+                    .findFirst()
+                    .ifPresent(typed -> typed.spread().add(complex.biomePickNoise(region, type, x, z)));
+        });
+        List<String> notes = new ArrayList<>();
+        PickMeasuring.addBiomeSpreadNotes(notes, spreads);
+        PickMeasuring.addChildBiomeNote(notes, complex, region);
+        List<NoisePickSpread> plainSpreads = spreads.stream().map(TypedSpread::spread).toList();
+        PickMeasuring.addRarityNotes(notes, complex, plainSpreads);
+        notes.add(PickMeasuring.measuredNote());
+        return new BiomePicks(region.getLoadKey(), region.getName(), plainSpreads, notes);
+    }
+
+    private static HeightPicks measureHeightPicks(Engine engine, IrisComplex complex, IrisRegion region, MapCensus.ViewArea area) {
+        List<Integer> heights = new ArrayList<>();
+        PickMeasuring.forEachSample(area, (x, z) -> heights.add((int) Math.round(complex.getPlacementHeightStream().get(x, z))));
+        RegionHeightCoverage coverage = RegionHeightCoverage.measure(PickMeasuring.biomeRanges(engine, region),
+                heights.stream().mapToInt(Integer::intValue).toArray());
+        List<String> notes = new ArrayList<>(coverage.notes());
+        notes.add(PickMeasuring.hybridNoiseNote());
+        return new HeightPicks(region.getLoadKey(), region.getName(), coverage, notes);
+    }
+
+    /**
+     * What was measured for the region view; the region key is null when every region was measured.
+     */
+    private sealed interface Measurement permits RegionPicks, BiomePicks, HeightPicks {
+        String regionKey();
+    }
+
+    private record RegionPicks(NoisePickSpread spread, List<String> notes) implements Measurement {
+        @Override
+        public String regionKey() {
+            return null;
+        }
+    }
+
+    private record BiomePicks(String regionKey, String regionName, List<NoisePickSpread> spreads, List<String> notes)
+            implements Measurement {
+    }
+
+    private record HeightPicks(String regionKey, String regionName, RegionHeightCoverage coverage, List<String> notes)
+            implements Measurement {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/RegionHeightChart.java

@@ -0,0 +1,343 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.core.gui.RegionHeightCoverage.BiomeRange;
+import com.volmit.iris.core.gui.RegionHeightCoverage.HeightBand;
+import com.volmit.iris.engine.object.InferredType;
+
+import javax.swing.JComponent;
+import java.awt.BasicStroke;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Rectangle;
+import java.awt.RenderingHints;
+import java.awt.Shape;
+import java.awt.event.MouseEvent;
+import java.util.List;
+
+/**
+ * Ground height runs left to right. On top, how much of the ground in view sits at each height; below, one bar per
+ * biome over the heights it allows. Heights no biome covers are red, heights several ranged biomes share are hatched.
+ */
+final class RegionHeightChart extends JComponent {
+    private static final long serialVersionUID = 6218894112903760545L;
+    private static final List<InferredType> ROW_GROUPS = List.of(InferredType.LAND, InferredType.SHORE, InferredType.SEA);
+    private static final int CHART_WIDTH = 330;
+    private static final int PADDING = 12;
+    private static final int NAME_COLUMN = 104;
+    private static final int NAME_GAP = 8;
+    private static final int HISTOGRAM_HEIGHT = 54;
+    private static final int AXIS_HEIGHT = 20;
+    private static final int GROUP_HEADER_HEIGHT = 22;
+    private static final int ROW_HEIGHT = 18;
+    private static final int BAR_HEIGHT = 10;
+    private static final int MINIMUM_TICK_SPACING = 38;
+    private static final int[] TICK_STEPS = {5, 10, 20, 25, 50, 100, 200, 250, 500, 1000};
+    private static final int HATCH_SPACING = 5;
+    private static final double RANGE_PADDING_FRACTION = 0.04D;
+    private static final Color LAND_GROUND = new ThemeColor(0x9DA0A8, 0x6F737A);
+    private static final Color SEA_GROUND = new ThemeColor(0x7FA3D9, 0x4A6FA8);
+    private static final Color GAP_FILL = new ThemeColor(new Color(0xDB, 0x3B, 0x4B, 46), new Color(0xF7, 0x54, 0x64, 52));
+    private static final Color SHARED_HATCH = new ThemeColor(new Color(0, 0, 0, 70), new Color(255, 255, 255, 70));
+    private static final Color SEA_LEVEL = new ThemeColor(new Color(0x31, 0x5F, 0xBD, 150), new Color(0x54, 0x8A, 0xF7, 150));
+
+    private RegionHeightCoverage coverage;
+    private int lowestShown;
+    private int highestShown;
+
+    RegionHeightChart() {
+        setToolTipText("");
+        setOpaque(false);
+    }
+
+    void show(RegionHeightCoverage nextCoverage) {
+        coverage = nextCoverage;
+        fitShownHeights();
+        revalidate();
+        repaint();
+    }
+
+    // The chart spans the ground in view and every range edge, so a biome placed above or below the view still shows.
+    private void fitShownHeights() {
+        if (coverage == null) {
+            return;
+        }
+        int lowest = Math.min(0, coverage.lowestHeight());
+        int highest = Math.max(0, coverage.highestHeight());
+        for (InferredType type : ROW_GROUPS) {
+            for (BiomeRange range : coverage.ranges(type)) {
+                if (range.hasLowerBound()) {
+                    lowest = Math.min(lowest, range.minHeight());
+                }
+                if (range.hasUpperBound()) {
+                    highest = Math.max(highest, range.maxHeight());
+                }
+            }
+        }
+        int padding = Math.max(2, (int) Math.round((highest - lowest) * RANGE_PADDING_FRACTION));
+        lowestShown = lowest - padding;
+        highestShown = highest + padding;
+    }
+
+    @Override
+    public Dimension getPreferredSize() {
+        int rows = 0;
+        int groups = 0;
+        if (coverage != null) {
+            for (InferredType type : ROW_GROUPS) {
+                int count = coverage.ranges(type).size();
+                rows += count;
+                groups += count > 0 ? 1 : 0;
+            }
+        }
+        int height = PADDING * 2 + HISTOGRAM_HEIGHT + AXIS_HEIGHT + groups * GROUP_HEADER_HEIGHT + rows * ROW_HEIGHT;
+        return StudioTheme.scaledSize(CHART_WIDTH, height);
+    }
+
+    @Override
+    public Dimension getMaximumSize() {
+        return new Dimension(Integer.MAX_VALUE, getPreferredSize().height);
+    }
+
+    @Override
+    protected void paintComponent(Graphics graphics) {
+        if (coverage == null) {
+            return;
+        }
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+            canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+            int top = StudioTheme.scale(PADDING);
+            int rowsTop = top + StudioTheme.scale(HISTOGRAM_HEIGHT + AXIS_HEIGHT);
+            int bottom = getHeight() - StudioTheme.scale(PADDING);
+            drawBands(canvas, top, bottom);
+            drawGround(canvas, top);
+            drawAxis(canvas, top + StudioTheme.scale(HISTOGRAM_HEIGHT));
+            drawRows(canvas, rowsTop);
+            drawSeaLevel(canvas, top, bottom);
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private void drawBands(Graphics2D canvas, int top, int bottom) {
+        int histogramBottom = top + StudioTheme.scale(HISTOGRAM_HEIGHT);
+        for (InferredType type : RegionHeightCoverage.MEASURED_TYPES) {
+            for (HeightBand band : coverage.bands(type)) {
+                int left = xOf(band.fromHeight());
+                int width = Math.max(1, xOf(band.toHeight() + 1) - left);
+                if (band.isGap()) {
+                    canvas.setColor(GAP_FILL);
+                    canvas.fillRect(left, top, width, bottom - top);
+                } else if (band.isShared() && band.biomes().stream().allMatch(BiomeRange::isBounded)) {
+                    hatch(canvas, new Rectangle(left, top, width, histogramBottom - top));
+                }
+            }
+        }
+    }
+
+    private static void hatch(Graphics2D canvas, Rectangle area) {
+        Shape previousClip = canvas.getClip();
+        canvas.clip(area);
+        canvas.setColor(SHARED_HATCH);
+        int spacing = StudioTheme.scale(HATCH_SPACING);
+        for (int offset = -area.height; offset < area.width; offset += spacing) {
+            canvas.drawLine(area.x + offset, area.y + area.height, area.x + offset + area.height, area.y);
+        }
+        canvas.setClip(previousClip);
+    }
+
+    private void drawGround(Graphics2D canvas, int top) {
+        int histogramHeight = StudioTheme.scale(HISTOGRAM_HEIGHT);
+        int plotLeft = plotLeft();
+        int plotRight = plotRight();
+        int[] columnCounts = new int[plotRight - plotLeft];
+        int highestColumn = 1;
+        for (int column = 0; column < columnCounts.length; column++) {
+            int fromHeight = heightAt(plotLeft + column);
+            int toHeight = Math.max(fromHeight, heightAt(plotLeft + column + 1) - 1);
+            for (int height = fromHeight; height <= toHeight; height++) {
+                columnCounts[column] += coverage.count(height);
+            }
+            highestColumn = Math.max(highestColumn, columnCounts[column]);
+        }
+        for (int column = 0; column < columnCounts.length; column++) {
+            if (columnCounts[column] == 0) {
+                continue;
+            }
+            int barHeight = Math.max(1, (int) Math.round(columnCounts[column] / (double) highestColumn * histogramHeight));
+            canvas.setColor(heightAt(plotLeft + column) < 0 ? SEA_GROUND : LAND_GROUND);
+            canvas.fillRect(plotLeft + column, top + histogramHeight - barHeight, 1, barHeight);
+        }
+    }
+
+    private void drawAxis(Graphics2D canvas, int axisTop) {
+        canvas.setFont(StudioTheme.smallFont());
+        FontMetrics metrics = canvas.getFontMetrics();
+        canvas.setColor(StudioTheme.CONTROL_BORDER);
+        canvas.drawLine(plotLeft(), axisTop, plotRight(), axisTop);
+        int step = tickStep();
+        int firstTick = Math.floorDiv(lowestShown, step) * step + step;
+        for (int height = firstTick; height < highestShown; height += step) {
+            int x = xOf(height);
+            String label = height > 0 ? "+" + height : String.valueOf(height);
+            canvas.setColor(StudioTheme.CONTROL_BORDER);
+            canvas.drawLine(x, axisTop, x, axisTop + StudioTheme.scale(3));
+            canvas.setColor(StudioTheme.MUTED_TEXT);
+            canvas.drawString(label, x - metrics.stringWidth(label) / 2, axisTop + StudioTheme.scale(4) + metrics.getAscent());
+        }
+        canvas.setColor(StudioTheme.MUTED_TEXT);
+        canvas.drawString("Heights in view", StudioTheme.scale(PADDING), axisTop - StudioTheme.scale(4));
+    }
+
+    private int tickStep() {
+        double pixelsPerBlock = (plotRight() - plotLeft()) / (double) Math.max(1, highestShown - lowestShown);
+        for (int step : TICK_STEPS) {
+            if (step * pixelsPerBlock >= StudioTheme.scale(MINIMUM_TICK_SPACING)) {
+                return step;
+            }
+        }
+        return TICK_STEPS[TICK_STEPS.length - 1];
+    }
+
+    private void drawRows(Graphics2D canvas, int rowsTop) {
+        int y = rowsTop;
+        for (InferredType type : ROW_GROUPS) {
+            List<BiomeRange> ranges = coverage.ranges(type);
+            if (ranges.isEmpty()) {
+                continue;
+            }
+            canvas.setFont(StudioTheme.sectionFont());
+            canvas.setColor(StudioTheme.MUTED_TEXT);
+            canvas.drawString(groupTitle(type), StudioTheme.scale(PADDING), y + StudioTheme.scale(GROUP_HEADER_HEIGHT) - StudioTheme.scale(7));
+            y += StudioTheme.scale(GROUP_HEADER_HEIGHT);
+            for (BiomeRange range : ranges) {
+                drawRow(canvas, range, y);
+                y += StudioTheme.scale(ROW_HEIGHT);
+            }
+        }
+    }
+
+    private void drawRow(Graphics2D canvas, BiomeRange range, int rowTop) {
+        int rowHeight = StudioTheme.scale(ROW_HEIGHT);
+        canvas.setFont(StudioTheme.smallFont());
+        FontMetrics metrics = canvas.getFontMetrics();
+        canvas.setColor(StudioTheme.SECONDARY_TEXT);
+        canvas.drawString(ellipsize(range.name(), metrics, StudioTheme.scale(NAME_COLUMN)), StudioTheme.scale(PADDING),
+                rowTop + (rowHeight + metrics.getAscent() - metrics.getDescent()) / 2);
+        int left = xOf(Math.max(range.minHeight(), lowestShown));
+        int right = xOf(Math.min(range.maxHeight(), highestShown) + 1);
+        int barHeight = StudioTheme.scale(BAR_HEIGHT);
+        int barTop = rowTop + (rowHeight - barHeight) / 2;
+        int arc = StudioTheme.scale(4);
+        canvas.setColor(new Color(range.color()));
+        canvas.fillRoundRect(left, barTop, Math.max(2, right - left), barHeight, arc, arc);
+        canvas.setColor(StudioTheme.CONTROL_BORDER);
+        canvas.drawRoundRect(left, barTop, Math.max(2, right - left) - 1, barHeight - 1, arc, arc);
+    }
+
+    private void drawSeaLevel(Graphics2D canvas, int top, int bottom) {
+        int x = xOf(0);
+        canvas.setColor(SEA_LEVEL);
+        float dash = StudioTheme.scale(3);
+        canvas.setStroke(new BasicStroke(1F, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER, 10F, new float[]{dash, dash}, 0F));
+        canvas.drawLine(x, top, x, bottom);
+    }
+
+    @Override
+    public String getToolTipText(MouseEvent event) {
+        if (coverage == null) {
+            return null;
+        }
+        BiomeRange row = rowAt(event.getY());
+        if (row != null) {
+            return row.name() + ": " + (row.isBounded() ? RegionHeightCoverage.heightText(row.minHeight(), row.maxHeight()) : "any height");
+        }
+        int height = heightAt(event.getX());
+        for (InferredType type : RegionHeightCoverage.MEASURED_TYPES) {
+            for (HeightBand band : coverage.bands(type)) {
+                if (band.isGap() && height >= band.fromHeight() && height <= band.toHeight()) {
+                    return "No biome covers " + RegionHeightCoverage.heightText(band.fromHeight(), band.toHeight());
+                }
+            }
+        }
+        return null;
+    }
+
+    private BiomeRange rowAt(int y) {
+        int rowTop = StudioTheme.scale(PADDING + HISTOGRAM_HEIGHT + AXIS_HEIGHT);
+        for (InferredType type : ROW_GROUPS) {
+            List<BiomeRange> ranges = coverage.ranges(type);
+            if (ranges.isEmpty()) {
+                continue;
+            }
+            rowTop += StudioTheme.scale(GROUP_HEADER_HEIGHT);
+            for (BiomeRange range : ranges) {
+                if (y >= rowTop && y < rowTop + StudioTheme.scale(ROW_HEIGHT)) {
+                    return range;
+                }
+                rowTop += StudioTheme.scale(ROW_HEIGHT);
+            }
+        }
+        return null;
+    }
+
+    private int plotLeft() {
+        return StudioTheme.scale(PADDING + NAME_COLUMN + NAME_GAP);
+    }
+
+    private int plotRight() {
+        return Math.max(plotLeft() + 1, getWidth() - StudioTheme.scale(PADDING));
+    }
+
+    private int xOf(int height) {
+        double fraction = (height - lowestShown) / (double) Math.max(1, highestShown - lowestShown);
+        return plotLeft() + (int) Math.round(fraction * (plotRight() - plotLeft()));
+    }
+
+    private int heightAt(int x) {
+        double fraction = (x - plotLeft()) / (double) Math.max(1, plotRight() - plotLeft());
+        return (int) Math.floor(lowestShown + fraction * (highestShown - lowestShown));
+    }
+
+    private static String groupTitle(InferredType type) {
+        return switch (type) {
+            case LAND -> "LAND";
+            case SHORE -> "SHORE";
+            default -> "SEA";
+        };
+    }
+
+    private static String ellipsize(String text, FontMetrics metrics, int maximumWidth) {
+        if (metrics.stringWidth(text) <= maximumWidth) {
+            return text;
+        }
+        String ellipsis = "…";
+        int end = text.length();
+        while (end > 0 && metrics.stringWidth(text.substring(0, end) + ellipsis) > maximumWidth) {
+            end--;
+        }
+        return text.substring(0, end) + ellipsis;
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/RegionHeightCoverage.java

@@ -0,0 +1,254 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.engine.object.InferredType;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Locale;
+import java.util.stream.Collectors;
+
+/**
+ * Which of a region's biomes allow which ground height in HYBRID terrain, measured against the ground heights the map
+ * shows, so the region view can point out heights no biome covers and heights several biomes share.
+ * Heights are in blocks above the fluid height, negative below it.
+ */
+final class RegionHeightCoverage {
+    static final List<InferredType> MEASURED_TYPES = List.of(InferredType.SEA, InferredType.LAND);
+    private static final int MAXIMUM_NOTES = 8;
+
+    private final List<BiomeRange> ranges;
+    private final int lowestHeight;
+    private final int highestHeight;
+    private final int[] countsFromLowest;
+    private final int highestCount;
+
+    private RegionHeightCoverage(List<BiomeRange> ranges, int lowestHeight, int[] countsFromLowest) {
+        this.ranges = List.copyOf(ranges);
+        this.lowestHeight = lowestHeight;
+        this.highestHeight = lowestHeight + countsFromLowest.length - 1;
+        this.countsFromLowest = countsFromLowest;
+        int highest = 0;
+        for (int count : countsFromLowest) {
+            highest = Math.max(highest, count);
+        }
+        this.highestCount = highest;
+    }
+
+    /**
+     * @param groundHeights the ground height of every sampled spot, rounded to whole blocks
+     */
+    static RegionHeightCoverage measure(List<BiomeRange> ranges, int[] groundHeights) {
+        if (groundHeights.length == 0) {
+            return new RegionHeightCoverage(ranges, 0, new int[1]);
+        }
+        int lowest = Integer.MAX_VALUE;
+        int highest = Integer.MIN_VALUE;
+        for (int height : groundHeights) {
+            lowest = Math.min(lowest, height);
+            highest = Math.max(highest, height);
+        }
+        int[] counts = new int[highest - lowest + 1];
+        for (int height : groundHeights) {
+            counts[height - lowest]++;
+        }
+        return new RegionHeightCoverage(ranges, lowest, counts);
+    }
+
+    List<BiomeRange> ranges(InferredType type) {
+        return ranges.stream().filter(range -> range.type() == type).toList();
+    }
+
+    int lowestHeight() {
+        return lowestHeight;
+    }
+
+    int highestHeight() {
+        return highestHeight;
+    }
+
+    int count(int height) {
+        return height < lowestHeight || height > highestHeight ? 0 : countsFromLowest[height - lowestHeight];
+    }
+
+    int highestCount() {
+        return highestCount;
+    }
+
+    /**
+     * The ground heights of one type split into runs that the same biomes allow, from low to high. Land is the ground
+     * at or above the fluid height, sea the ground below it.
+     */
+    List<HeightBand> bands(InferredType type) {
+        int from = type == InferredType.SEA ? lowestHeight : Math.max(0, lowestHeight);
+        int to = type == InferredType.SEA ? Math.min(-1, highestHeight) : highestHeight;
+        int total = countBetween(from, to);
+        List<HeightBand> bands = new ArrayList<>();
+        if (total == 0) {
+            return bands;
+        }
+        List<BiomeRange> typeRanges = ranges(type);
+        int bandStart = from;
+        List<BiomeRange> bandBiomes = coveringBiomes(typeRanges, from);
+        for (int height = from + 1; height <= to + 1; height++) {
+            List<BiomeRange> biomes = height <= to ? coveringBiomes(typeRanges, height) : null;
+            if (bandBiomes.equals(biomes)) {
+                continue;
+            }
+            bands.add(new HeightBand(type, bandStart, height - 1, bandBiomes, countBetween(bandStart, height - 1) / (double) total));
+            bandStart = height;
+            bandBiomes = biomes;
+        }
+        return bands;
+    }
+
+    List<String> notes() {
+        List<String> notes = new ArrayList<>();
+        noteBiomesWithoutRange(notes);
+        for (InferredType type : MEASURED_TYPES) {
+            for (HeightBand band : bands(type)) {
+                if (band.share() == 0D) {
+                    continue;
+                }
+                if (band.isGap()) {
+                    notes.add(gapNote(band));
+                } else if (band.isShared() && band.biomes().stream().allMatch(BiomeRange::isBounded)) {
+                    notes.add(names(band.biomes()) + " share " + heightText(band.fromHeight(), band.toHeight())
+                            + ": their noise decides.");
+                }
+            }
+        }
+        return notes.size() > MAXIMUM_NOTES ? notes.subList(0, MAXIMUM_NOTES) : notes;
+    }
+
+    private void noteBiomesWithoutRange(List<String> notes) {
+        List<BiomeRange> unbounded = ranges.stream()
+                .filter(range -> range.type() != InferredType.SHORE && !range.isBounded())
+                .toList();
+        if (unbounded.isEmpty()) {
+            return;
+        }
+        boolean single = unbounded.size() == 1;
+        notes.add(names(unbounded) + (single ? " has no height range, so it" : " have no height range, so they")
+                + " can show up at any height.");
+    }
+
+    private String gapNote(HeightBand gap) {
+        String ground = gap.type() == InferredType.SEA ? "sea floor" : "land";
+        String note = "Nothing covers " + heightText(gap.fromHeight(), gap.toHeight()) + " (" + percent(gap.share())
+                + " of the " + ground + " in view)";
+        BiomeRange below = closestBelow(gap);
+        BiomeRange above = closestAbove(gap);
+        if (below != null && above != null) {
+            return note + ": " + below.name() + " and " + above.name() + ", the closest ranges, take it over.";
+        }
+        BiomeRange closest = below != null ? below : above;
+        return closest == null ? note + "." : note + ": " + closest.name() + ", the closest range, takes it over.";
+    }
+
+    private BiomeRange closestBelow(HeightBand gap) {
+        return ranges(gap.type()).stream()
+                .filter(range -> range.maxHeight() < gap.fromHeight())
+                .max(Comparator.comparingInt(BiomeRange::maxHeight))
+                .orElse(null);
+    }
+
+    private BiomeRange closestAbove(HeightBand gap) {
+        return ranges(gap.type()).stream()
+                .filter(range -> range.minHeight() > gap.toHeight())
+                .min(Comparator.comparingInt(BiomeRange::minHeight))
+                .orElse(null);
+    }
+
+    private static List<BiomeRange> coveringBiomes(List<BiomeRange> typeRanges, int height) {
+        return typeRanges.stream().filter(range -> range.covers(height)).toList();
+    }
+
+    private int countBetween(int from, int to) {
+        int total = 0;
+        for (int height = from; height <= to; height++) {
+            total += count(height);
+        }
+        return total;
+    }
+
+    static String heightText(int from, int to) {
+        if (from >= 0) {
+            return from == to ? from + " above sea" : from + " to " + to + " above sea";
+        }
+        if (to < 0) {
+            return from == to ? -from + " below sea" : -to + " to " + -from + " below sea";
+        }
+        return -from + " below to " + to + " above sea";
+    }
+
+    private static String names(List<BiomeRange> biomes) {
+        List<String> names = biomes.stream().map(BiomeRange::name).toList();
+        if (names.size() == 1) {
+            return names.get(0);
+        }
+        return names.subList(0, names.size() - 1).stream().collect(Collectors.joining(", ")) + " and " + names.get(names.size() - 1);
+    }
+
+    private static String percent(double share) {
+        double percent = share * 100D;
+        return percent < 1D ? "<1%" : String.format(Locale.ROOT, "%.0f%%", percent);
+    }
+
+    /**
+     * The heights one of the region's biomes allows, from its placement.
+     */
+    record BiomeRange(String key, String name, int color, InferredType type, int minHeight, int maxHeight) {
+        private static final int UNBOUNDED_LOW = -2032;
+        private static final int UNBOUNDED_HIGH = 2032;
+
+        boolean covers(int height) {
+            return height >= minHeight && height <= maxHeight;
+        }
+
+        boolean isBounded() {
+            return hasLowerBound() || hasUpperBound();
+        }
+
+        boolean hasLowerBound() {
+            return minHeight > UNBOUNDED_LOW;
+        }
+
+        boolean hasUpperBound() {
+            return maxHeight < UNBOUNDED_HIGH;
+        }
+    }
+
+    /**
+     * A run of ground heights that the same biomes allow; no biomes makes it a gap.
+     *
+     * @param share how much of this type's ground in view lies in the run
+     */
+    record HeightBand(InferredType type, int fromHeight, int toHeight, List<BiomeRange> biomes, double share) {
+        boolean isGap() {
+            return biomes.isEmpty();
+        }
+
+        boolean isShared() {
+            return biomes.size() > 1;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/RegionNavigator.java

@@ -0,0 +1,173 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.DefaultListCellRenderer;
+import javax.swing.DefaultListModel;
+import javax.swing.JList;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+import javax.swing.ListSelectionModel;
+import javax.swing.event.DocumentEvent;
+import javax.swing.event.DocumentListener;
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.util.List;
+import java.util.Locale;
+import java.util.Objects;
+import java.util.function.Consumer;
+
+/**
+ * The region view's sidebar: every region of the pack, or all of them at once, to fill the map with.
+ */
+final class RegionNavigator extends JPanel {
+    private static final long serialVersionUID = 3150735486722101466L;
+    private static final RegionRow ALL_REGIONS = new RegionRow(null, "All regions", -1);
+    private static final int ROW_HEIGHT = 24;
+    private static final int SWATCH_SIZE = 12;
+    private static final int SWATCH_GAP = 8;
+    private static final int ROW_PADDING = 10;
+
+    private final Consumer<String> onRegionChosen;
+    private final JTextField searchField = new JTextField();
+    private final DefaultListModel<RegionRow> rows = new DefaultListModel<>();
+    private final JList<RegionRow> list = new JList<>(rows);
+    private List<RegionRow> regions = List.of();
+    private String chosenKey;
+    private boolean updatingRows;
+
+    /**
+     * @param onRegionChosen receives the chosen region's key, or null for all regions
+     */
+    RegionNavigator(Consumer<String> onRegionChosen) {
+        super(new BorderLayout());
+        this.onRegionChosen = onRegionChosen;
+        StudioToolbar.makeSearchField(searchField, "Search regions...");
+        searchField.getDocument().addDocumentListener(new DocumentListener() {
+            @Override
+            public void insertUpdate(DocumentEvent event) {
+                showMatchingRows();
+            }
+
+            @Override
+            public void removeUpdate(DocumentEvent event) {
+                showMatchingRows();
+            }
+
+            @Override
+            public void changedUpdate(DocumentEvent event) {
+                showMatchingRows();
+            }
+        });
+        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
+        list.setFixedCellHeight(StudioTheme.scale(ROW_HEIGHT));
+        list.setCellRenderer(new RegionRowRenderer());
+        list.addListSelectionListener(event -> {
+            RegionRow row = list.getSelectedValue();
+            if (!event.getValueIsAdjusting() && !updatingRows && row != null && !Objects.equals(row.key(), chosenKey)) {
+                chosenKey = row.key();
+                onRegionChosen.accept(chosenKey);
+            }
+        });
+        add(StudioToolbar.padded(searchField, 8, 8, 8, 8), BorderLayout.NORTH);
+        add(StudioToolbar.scroll(list), BorderLayout.CENTER);
+        showMatchingRows();
+    }
+
+    void showRegions(List<RegionRow> nextRegions) {
+        regions = List.copyOf(nextRegions);
+        showMatchingRows();
+    }
+
+    private void showMatchingRows() {
+        String filter = searchField.getText().trim().toLowerCase(Locale.ROOT);
+        updatingRows = true;
+        try {
+            rows.clear();
+            rows.addElement(ALL_REGIONS);
+            for (RegionRow region : regions) {
+                if (filter.isEmpty() || region.name().toLowerCase(Locale.ROOT).contains(filter)
+                        || region.key().toLowerCase(Locale.ROOT).contains(filter)) {
+                    rows.addElement(region);
+                }
+            }
+            selectChosenRow();
+        } finally {
+            updatingRows = false;
+        }
+    }
+
+    private void selectChosenRow() {
+        for (int index = 0; index < rows.size(); index++) {
+            if (Objects.equals(rows.get(index).key(), chosenKey)) {
+                list.setSelectedIndex(index);
+                return;
+            }
+        }
+        list.clearSelection();
+    }
+
+    /**
+     * @param color the region's map colour, or -1 for the all regions row
+     */
+    record RegionRow(String key, String name, int color) {
+    }
+
+    private static final class RegionRowRenderer extends DefaultListCellRenderer {
+        private static final long serialVersionUID = -6114522950207432516L;
+        private Color swatch;
+
+        @Override
+        public Component getListCellRendererComponent(JList<?> owner, Object value, int index, boolean selected, boolean focused) {
+            RegionRow row = (RegionRow) value;
+            super.getListCellRendererComponent(owner, row.name(), index, selected, false);
+            setFont(row.key() == null ? StudioTheme.boldFont() : StudioTheme.font());
+            setBorder(StudioTheme.emptyBorder(0, ROW_PADDING + SWATCH_SIZE + SWATCH_GAP, 0, ROW_PADDING));
+            setToolTipText(row.key());
+            swatch = row.color() < 0 ? null : new Color(row.color());
+            return this;
+        }
+
+        @Override
+        protected void paintComponent(Graphics graphics) {
+            super.paintComponent(graphics);
+            if (swatch == null) {
+                return;
+            }
+            Graphics2D canvas = (Graphics2D) graphics.create();
+            try {
+                canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+                int size = StudioTheme.scale(SWATCH_SIZE);
+                int x = StudioTheme.scale(ROW_PADDING);
+                int y = (getHeight() - size) / 2;
+                int arc = StudioTheme.scale(4);
+                canvas.setColor(swatch);
+                canvas.fillRoundRect(x, y, size, size, arc, arc);
+                canvas.setColor(StudioTheme.CONTROL_BORDER);
+                canvas.drawRoundRect(x, y, size - 1, size - 1, arc, arc);
+            } finally {
+                canvas.dispose();
+            }
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/StickyFolderHeaders.java

@@ -0,0 +1,268 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.CellRendererPane;
+import javax.swing.Icon;
+import javax.swing.JComponent;
+import javax.swing.JLayer;
+import javax.swing.JScrollPane;
+import javax.swing.JTree;
+import javax.swing.JViewport;
+import javax.swing.SwingUtilities;
+import javax.swing.UIManager;
+import javax.swing.plaf.LayerUI;
+import javax.swing.plaf.basic.BasicTreeUI;
+import javax.swing.tree.TreePath;
+import java.awt.AWTEvent;
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.Cursor;
+import java.awt.GradientPaint;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Point;
+import java.awt.Rectangle;
+import java.awt.event.MouseEvent;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Keeps the folders around the top row of a scrolled tree pinned at the top, so a long folder never hides where it
+ * is. The next folder pushes the last header up as it arrives, and clicking a header jumps to its folder.
+ */
+final class StickyFolderHeaders extends LayerUI<JScrollPane> {
+    private static final long serialVersionUID = -2205474187531254372L;
+    private static final int SHADOW_HEIGHT = 4;
+    private static final Color SHADOW = new ThemeColor(new Color(0, 0, 0, 28), new Color(0, 0, 0, 90));
+    private static final Color NO_SHADOW = new Color(0, 0, 0, 0);
+    // The folder handle sits one indent to the left of the folder's name, as the tree draws it.
+    private static final int HANDLE_NUDGE = 1;
+
+    private final JTree tree;
+    private final CellRendererPane rendererPane = new CellRendererPane();
+    private transient JLayer<JScrollPane> layer;
+    private int hoveredHeader = -1;
+
+    private StickyFolderHeaders(JTree tree) {
+        this.tree = tree;
+    }
+
+    static JLayer<JScrollPane> around(JTree tree, JScrollPane scrollPane) {
+        // Copying the scrolled pixels would drag the pinned headers along, so every scroll repaints instead.
+        scrollPane.getViewport().setScrollMode(JViewport.SIMPLE_SCROLL_MODE);
+        StickyFolderHeaders headers = new StickyFolderHeaders(tree);
+        JLayer<JScrollPane> layer = new JLayer<>(scrollPane, headers);
+        scrollPane.getViewport().addChangeListener(event -> layer.repaint());
+        return layer;
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public void installUI(JComponent component) {
+        super.installUI(component);
+        layer = (JLayer<JScrollPane>) component;
+        layer.setLayerEventMask(AWTEvent.MOUSE_EVENT_MASK | AWTEvent.MOUSE_MOTION_EVENT_MASK);
+        tree.add(rendererPane);
+    }
+
+    @Override
+    public void uninstallUI(JComponent component) {
+        layer.setLayerEventMask(0);
+        tree.remove(rendererPane);
+        layer = null;
+        super.uninstallUI(component);
+    }
+
+    @Override
+    public void paint(Graphics graphics, JComponent component) {
+        super.paint(graphics, component);
+        List<Header> headers = pinnedHeaders();
+        if (headers.isEmpty()) {
+            return;
+        }
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            Rectangle viewport = viewportBounds();
+            canvas.clipRect(viewport.x, viewport.y, viewport.width, viewport.height);
+            for (int index = 0; index < headers.size(); index++) {
+                paintHeader(canvas, headers.get(index), index == hoveredHeader, viewport);
+            }
+            Header last = headers.get(headers.size() - 1);
+            int shadowTop = viewport.y + last.top() + tree.getRowHeight();
+            canvas.setPaint(new GradientPaint(0, shadowTop, SHADOW, 0, shadowTop + StudioTheme.scale(SHADOW_HEIGHT), NO_SHADOW));
+            canvas.fillRect(viewport.x, shadowTop, viewport.width, StudioTheme.scale(SHADOW_HEIGHT));
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private void paintHeader(Graphics2D canvas, Header header, boolean hovered, Rectangle viewport) {
+        int rowHeight = tree.getRowHeight();
+        int top = viewport.y + header.top();
+        Rectangle row = tree.getRowBounds(header.row());
+        int left = viewport.x + row.x - scrolledView().x;
+        canvas.setColor(hovered ? StudioTheme.HOVER_BACKGROUND : tree.getBackground());
+        canvas.fillRect(viewport.x, top, viewport.width, rowHeight);
+        paintFolderHandle(canvas, left, top + rowHeight / 2);
+        Component renderer = tree.getCellRenderer().getTreeCellRendererComponent(
+                tree, header.path().getLastPathComponent(), false, true, false, header.row(), false);
+        rendererPane.paintComponent(canvas, renderer, tree, left, top, viewport.x + viewport.width - left, rowHeight, true);
+    }
+
+    private void paintFolderHandle(Graphics2D canvas, int folderLeft, int middleY) {
+        Icon handle = UIManager.getIcon("Tree.expandedIcon");
+        if (handle == null || !(tree.getUI() instanceof BasicTreeUI treeUI)) {
+            return;
+        }
+        int middleX = folderLeft - treeUI.getRightChildIndent() + HANDLE_NUDGE;
+        handle.paintIcon(tree, canvas, middleX - handle.getIconWidth() / 2, middleY - handle.getIconHeight() / 2);
+    }
+
+    @Override
+    protected void processMouseEvent(MouseEvent event, JLayer<? extends JScrollPane> source) {
+        if (event.getID() == MouseEvent.MOUSE_EXITED) {
+            hover(-1);
+            return;
+        }
+        int index = headerAt(event);
+        if (index < 0) {
+            return;
+        }
+        event.consume();
+        if (event.getID() == MouseEvent.MOUSE_CLICKED && SwingUtilities.isLeftMouseButton(event)) {
+            jumpTo(pinnedHeaders().get(index), index);
+        }
+    }
+
+    @Override
+    protected void processMouseMotionEvent(MouseEvent event, JLayer<? extends JScrollPane> source) {
+        hover(headerAt(event));
+    }
+
+    private void hover(int index) {
+        if (index == hoveredHeader) {
+            return;
+        }
+        hoveredHeader = index;
+        tree.setCursor(index >= 0 ? Cursor.getPredefinedCursor(Cursor.HAND_CURSOR) : null);
+        layer.repaint();
+    }
+
+    // The folder lands just below the headers of the folders around it.
+    private void jumpTo(Header header, int level) {
+        Rectangle row = tree.getRowBounds(header.row());
+        JViewport viewport = layer.getView().getViewport();
+        int top = Math.max(0, row.y - level * tree.getRowHeight());
+        int bottomLimit = Math.max(0, tree.getHeight() - viewport.getExtentSize().height);
+        viewport.setViewPosition(new Point(viewport.getViewPosition().x, Math.min(top, bottomLimit)));
+    }
+
+    private int headerAt(MouseEvent event) {
+        if (layer == null || event.getComponent() == null) {
+            return -1;
+        }
+        Point point = SwingUtilities.convertPoint(event.getComponent(), event.getPoint(), layer);
+        Rectangle viewport = viewportBounds();
+        if (!viewport.contains(point)) {
+            return -1;
+        }
+        List<Header> headers = pinnedHeaders();
+        for (int index = headers.size() - 1; index >= 0; index--) {
+            int top = viewport.y + headers.get(index).top();
+            if (point.y >= top && point.y < top + tree.getRowHeight()) {
+                return index;
+            }
+        }
+        return -1;
+    }
+
+    /**
+     * For each depth, the folder holding the row just under the headers above it, as long as that folder's own row
+     * has scrolled out of sight.
+     */
+    private List<Header> pinnedHeaders() {
+        List<Header> headers = new ArrayList<>();
+        int rowHeight = tree.getRowHeight();
+        if (layer == null || rowHeight <= 0 || tree.getRowCount() == 0) {
+            return headers;
+        }
+        Rectangle view = scrolledView();
+        for (int level = 0; ; level++) {
+            int slotTop = level * rowHeight;
+            int row = tree.getClosestRowForLocation(view.x, view.y + slotTop);
+            TreePath path = row < 0 ? null : tree.getPathForRow(row);
+            if (path == null || !isInsideFolderAt(path, level)) {
+                return headers;
+            }
+            TreePath folder = ancestorAt(path, level);
+            Rectangle lastRow = tree.getRowBounds(lastRowInside(folder, row));
+            int top = Math.min(slotTop, lastRow.y + lastRow.height - view.y - rowHeight);
+            headers.add(new Header(folder, tree.getRowForPath(folder), top));
+            if (top < slotTop) {
+                return headers;
+            }
+        }
+    }
+
+    // The hidden root is the path's first element, so the folder at depth 0 is its second.
+    private static boolean isInsideFolderAt(TreePath path, int level) {
+        return path.getPathCount() > level + 2;
+    }
+
+    private static TreePath ancestorAt(TreePath path, int level) {
+        TreePath ancestor = path;
+        while (ancestor.getPathCount() > level + 2) {
+            ancestor = ancestor.getParentPath();
+        }
+        return ancestor;
+    }
+
+    // A folder's rows sit together, so the last one is found by halving the rows after a row known to be inside.
+    private int lastRowInside(TreePath folder, int rowInside) {
+        int low = rowInside;
+        int high = tree.getRowCount() - 1;
+        while (low < high) {
+            int middle = (low + high + 1) >>> 1;
+            if (folder.isDescendant(tree.getPathForRow(middle))) {
+                low = middle;
+            } else {
+                high = middle - 1;
+            }
+        }
+        return low;
+    }
+
+    private Rectangle scrolledView() {
+        return layer.getView().getViewport().getViewRect();
+    }
+
+    private Rectangle viewportBounds() {
+        JViewport viewport = layer.getView().getViewport();
+        Point origin = SwingUtilities.convertPoint(viewport, 0, 0, layer);
+        return new Rectangle(origin.x, origin.y, viewport.getWidth(), viewport.getHeight());
+    }
+
+    /**
+     * A pinned folder, its row in the tree and how far below the top of the visible rows it is drawn.
+     */
+    private record Header(TreePath path, int row, int top) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/StudioOverlay.java

@@ -0,0 +1,64 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import java.awt.Color;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.awt.Shape;
+import java.awt.geom.RoundRectangle2D;
+
+/**
+ * Draws the floating cards (legends, hover details, hints) on top of a map, styled like IntelliJ's popups.
+ */
+final class StudioOverlay {
+    private static final Color FOOTER_BACKGROUND = new ThemeColor(0xF7F8FA, 0x27292C);
+
+    private StudioOverlay() {
+    }
+
+    static void drawCard(Graphics2D canvas, int x, int y, int width, int height) {
+        drawCard(canvas, x, y, width, height, 0);
+    }
+
+    /**
+     * Draws a card whose bottom {@code footerHeight} pixels are a darker bar, like the shortcut bar of IntelliJ's popups.
+     */
+    static void drawCard(Graphics2D canvas, int x, int y, int width, int height, int footerHeight) {
+        Graphics2D card = (Graphics2D) canvas.create();
+        card.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+        RoundRectangle2D outline = new RoundRectangle2D.Double(x + 0.5D, y + 0.5D, width - 1D, height - 1D,
+                StudioTheme.scale(StudioTheme.OVERLAY_ARC), StudioTheme.scale(StudioTheme.OVERLAY_ARC));
+        card.setColor(StudioTheme.OVERLAY_BACKGROUND);
+        card.fill(outline);
+        if (footerHeight > 0) {
+            int footerTop = y + height - footerHeight;
+            Shape cardClip = card.getClip();
+            card.clip(outline);
+            card.setColor(FOOTER_BACKGROUND);
+            card.fillRect(x, footerTop, width, footerHeight);
+            card.setColor(StudioTheme.OVERLAY_BORDER);
+            card.fillRect(x, footerTop, width, 1);
+            card.setClip(cardClip);
+        }
+        card.setColor(StudioTheme.OVERLAY_BORDER);
+        card.draw(outline);
+        card.dispose();
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/StudioStatusBar.java

@@ -0,0 +1,110 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.BorderFactory;
+import javax.swing.Box;
+import javax.swing.BoxLayout;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JProgressBar;
+import java.awt.Dimension;
+import java.util.Objects;
+
+/**
+ * An IntelliJ style status bar: what is shown on the left, work in progress in the middle and where the pointer is on the right.
+ */
+final class StudioStatusBar extends JPanel {
+    private static final long serialVersionUID = 6302468216735125611L;
+    private static final int HEIGHT = 26;
+    private static final int PROGRESS_STEPS = 1_000;
+
+    private final JLabel summary = statusLabel();
+    private final JLabel activity = statusLabel();
+    private final JProgressBar progress = new JProgressBar(0, PROGRESS_STEPS);
+    private final JLabel position = statusLabel();
+
+    StudioStatusBar() {
+        setLayout(new BoxLayout(this, BoxLayout.X_AXIS));
+        setBackground(StudioTheme.PANEL_BACKGROUND);
+        setBorder(BorderFactory.createCompoundBorder(
+                BorderFactory.createMatteBorder(1, 0, 0, 0, StudioTheme.SEPARATOR),
+                StudioTheme.emptyBorder(0, 10, 0, 10)
+        ));
+        setPreferredSize(StudioTheme.scaledSize(0, HEIGHT));
+        progress.setMaximumSize(StudioTheme.scaledSize(120, 4));
+        progress.setPreferredSize(StudioTheme.scaledSize(120, 4));
+        progress.setVisible(false);
+        allowShrinking(summary);
+        allowShrinking(activity);
+        add(summary);
+        add(Box.createHorizontalGlue());
+        add(activity);
+        add(Box.createHorizontalStrut(StudioTheme.scale(8)));
+        add(progress);
+        add(Box.createHorizontalStrut(StudioTheme.scale(18)));
+        add(position);
+    }
+
+    void showSummary(String text) {
+        setTextIfChanged(summary, text);
+        summary.setForeground(StudioTheme.SECONDARY_TEXT);
+    }
+
+    void showError(String text) {
+        setTextIfChanged(summary, text);
+        summary.setForeground(StudioTheme.ERROR);
+    }
+
+    void showActivity(String text) {
+        setTextIfChanged(activity, text);
+    }
+
+    void showProgress(double completion) {
+        boolean working = completion < 1D;
+        progress.setVisible(working);
+        if (working) {
+            progress.setValue((int) Math.round(Math.max(0D, completion) * PROGRESS_STEPS));
+        }
+    }
+
+    void showPosition(String text) {
+        setTextIfChanged(position, text);
+    }
+
+    // Long text gives way with an ellipsis instead of pushing the other parts of the bar out of view.
+    private static void allowShrinking(JLabel label) {
+        label.setMinimumSize(new Dimension(0, 0));
+    }
+
+    private static JLabel statusLabel() {
+        JLabel label = new JLabel();
+        label.setFont(StudioTheme.smallFont());
+        label.setForeground(StudioTheme.SECONDARY_TEXT);
+        return label;
+    }
+
+    // Status text changes on every mouse move, and an unchanged label shouldn't trigger a relayout.
+    private static void setTextIfChanged(JLabel label, String text) {
+        String next = text == null ? "" : text;
+        if (!Objects.equals(label.getText(), next)) {
+            label.setText(next);
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/StudioTheme.java

@@ -0,0 +1,291 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.formdev.flatlaf.FlatDarkLaf;
+import com.formdev.flatlaf.FlatLaf;
+import com.formdev.flatlaf.FlatLightLaf;
+import com.formdev.flatlaf.util.UIScale;
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.IrisSettings;
+
+import javax.swing.BorderFactory;
+import javax.swing.UIManager;
+import javax.swing.border.Border;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.EventQueue;
+import java.awt.Font;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * The colours of IntelliJ's "New UI", light and dark, shared by FlatLaf's controls and everything the studio windows
+ * draw themselves. The theme follows the system unless the user picked light or dark.
+ */
+final class StudioTheme {
+    static final Color EDITOR_BACKGROUND = new ThemeColor(0xFFFFFF, 0x1E1F22);
+    static final Color PANEL_BACKGROUND = new ThemeColor(0xF7F8FA, 0x2B2D30);
+    static final Color HOVER_BACKGROUND = new ThemeColor(0xDFE1E5, 0x393B40);
+    static final Color INACTIVE_SELECTION = new ThemeColor(0xDFE1E5, 0x43454A);
+    static final Color SELECTION = new ThemeColor(0xD4E2FF, 0x2E436E);
+    static final Color CONTROL_BORDER = new ThemeColor(0xC9CCD6, 0x4E5157);
+    static final Color SEPARATOR = new ThemeColor(0xEBECF0, 0x1E1F22);
+    static final Color TEXT = new ThemeColor(0x000000, 0xDFE1E5);
+    static final ThemeColor SECONDARY_TEXT = new ThemeColor(0x6C707E, 0x9DA0A8);
+    static final Color MUTED_TEXT = new ThemeColor(0x818594, 0x6F737A);
+    static final Color ACCENT = new Color(0x3574F0);
+    static final Color LINK = new ThemeColor(0x315FBD, 0x548AF7);
+    static final Color ERROR = new ThemeColor(0xDB3B4B, 0xF75464);
+    static final Color WARNING = new ThemeColor(0xC27D04, 0xF2C55C);
+    static final Color SUCCESS = new ThemeColor(0x208A3C, 0x5FB865);
+    static final Color OVERLAY_BACKGROUND = new ThemeColor(new Color(0xFF, 0xFF, 0xFF, 240), new Color(0x2B, 0x2D, 0x30, 236));
+    static final Color OVERLAY_BORDER = new ThemeColor(0xDFE1E5, 0x43454A);
+    static final int OVERLAY_ARC = 10;
+
+    private static final boolean DARK_WITHOUT_SYSTEM_PREFERENCE = true;
+    private static final AtomicBoolean INSTALLED = new AtomicBoolean();
+    private static final ExecutorService SYSTEM_CHECK = Executors.newSingleThreadExecutor(runnable -> {
+        Thread thread = new Thread(runnable, "Iris Theme Check");
+        thread.setDaemon(true);
+        return thread;
+    });
+    private static volatile boolean dark = DARK_WITHOUT_SYSTEM_PREFERENCE;
+    private static volatile float pixelScale = 1F;
+    private static final Map<String, String> SHARED_DEFAULTS = Map.ofEntries(
+            Map.entry("Component.focusWidth", "1"),
+            Map.entry("Component.innerFocusWidth", "0"),
+            Map.entry("Component.arc", "8"),
+            Map.entry("Button.arc", "8"),
+            Map.entry("TextComponent.arc", "8"),
+            Map.entry("List.selectionArc", "6"),
+            Map.entry("List.selectionInsets", "0,6,0,6"),
+            Map.entry("Tree.selectionArc", "6"),
+            Map.entry("Tree.selectionInsets", "0,6,0,6"),
+            Map.entry("Tree.border", "0,8,0,0"),
+            Map.entry("ScrollBar.width", "10"),
+            Map.entry("ScrollBar.thumbArc", "999"),
+            Map.entry("ScrollBar.thumbInsets", "2,2,2,2"),
+            Map.entry("ScrollBar.showButtons", "false"),
+            Map.entry("ScrollPane.border", "0,0,0,0"),
+            Map.entry("SplitPane.dividerSize", "1"),
+            Map.entry("SplitPaneDivider.style", "plain"),
+            Map.entry("ProgressBar.arc", "999"),
+            Map.entry("ProgressBar.horizontalSize", "120,4")
+    );
+    private static final Map<String, String> DARK_DEFAULTS = withShared(Map.ofEntries(
+            Map.entry("@background", "#2B2D30"),
+            Map.entry("@foreground", "#DFE1E5"),
+            Map.entry("@accentColor", "#3574F0"),
+            Map.entry("@selectionBackground", "#2E436E"),
+            Map.entry("@selectionInactiveBackground", "#43454A"),
+            Map.entry("@disabledForeground", "#6F737A"),
+            Map.entry("Component.borderColor", "#4E5157"),
+            Map.entry("Component.focusedBorderColor", "#3574F0"),
+            Map.entry("Button.toolbar.hoverBackground", "#393B40"),
+            Map.entry("Button.toolbar.pressedBackground", "#43454A"),
+            Map.entry("Button.toolbar.selectedBackground", "#43454A"),
+            Map.entry("ToggleButton.toolbar.selectedBackground", "#43454A"),
+            Map.entry("ScrollBar.track", "#2B2D30"),
+            Map.entry("SplitPane.background", "#1E1F22"),
+            Map.entry("Separator.foreground", "#1E1F22"),
+            Map.entry("ToolTip.background", "#393B40")
+    ));
+    private static final Map<String, String> LIGHT_DEFAULTS = withShared(Map.ofEntries(
+            Map.entry("@background", "#F7F8FA"),
+            Map.entry("@foreground", "#000000"),
+            Map.entry("@accentColor", "#3574F0"),
+            Map.entry("@selectionBackground", "#D4E2FF"),
+            Map.entry("@selectionForeground", "#000000"),
+            Map.entry("@selectionInactiveBackground", "#DFE1E5"),
+            Map.entry("@selectionInactiveForeground", "#000000"),
+            Map.entry("@disabledForeground", "#A8ADBD"),
+            Map.entry("Component.borderColor", "#C9CCD6"),
+            Map.entry("Component.focusedBorderColor", "#3574F0"),
+            Map.entry("Button.toolbar.hoverBackground", "#DFE1E5"),
+            Map.entry("Button.toolbar.pressedBackground", "#C9CCD6"),
+            Map.entry("Button.toolbar.selectedBackground", "#DFE1E5"),
+            Map.entry("ToggleButton.toolbar.selectedBackground", "#DFE1E5"),
+            Map.entry("ScrollBar.track", "#F7F8FA"),
+            Map.entry("SplitPane.background", "#EBECF0"),
+            Map.entry("Separator.foreground", "#EBECF0")
+    ));
+
+    private StudioTheme() {
+    }
+
+    static void install() {
+        if (!INSTALLED.compareAndSet(false, true)) {
+            return;
+        }
+        try {
+            applyLookAndFeel(darkFor(mode()));
+            pixelScale = UIScale.getUserScaleFactor();
+        } catch (Throwable error) {
+            Iris.reportError(error);
+            Iris.warn("Could not apply the Iris studio theme, the studio windows will use Java's default look.");
+        }
+    }
+
+    static boolean isDark() {
+        return dark;
+    }
+
+    static Mode mode() {
+        return Mode.fromSetting(IrisSettings.get().getGui().getTheme());
+    }
+
+    /**
+     * Remembers the user's choice and switches every studio window to it.
+     */
+    static void choose(Mode next) {
+        IrisSettings settings = IrisSettings.get();
+        settings.getGui().setTheme(next.settingName());
+        settings.forceSave();
+        if (next == Mode.AUTO) {
+            followSystem();
+            return;
+        }
+        switchTo(next == Mode.DARK);
+    }
+
+    // Studio windows call this when they come to the front, so a change made in the system's settings shows up.
+    static void followSystem() {
+        if (!INSTALLED.get() || mode() != Mode.AUTO) {
+            return;
+        }
+        SYSTEM_CHECK.execute(() -> {
+            boolean systemDark = SystemAppearance.prefersDark().orElse(DARK_WITHOUT_SYSTEM_PREFERENCE);
+            EventQueue.invokeLater(() -> switchTo(systemDark));
+        });
+    }
+
+    private static boolean darkFor(Mode chosen) {
+        return switch (chosen) {
+            case LIGHT -> false;
+            case DARK -> true;
+            case AUTO -> SystemAppearance.prefersDark().orElse(DARK_WITHOUT_SYSTEM_PREFERENCE);
+        };
+    }
+
+    private static void switchTo(boolean nextDark) {
+        if (nextDark == dark) {
+            return;
+        }
+        applyLookAndFeel(nextDark);
+        FlatLaf.updateUI();
+    }
+
+    private static void applyLookAndFeel(boolean nextDark) {
+        dark = nextDark;
+        FlatLaf.setGlobalExtraDefaults(nextDark ? DARK_DEFAULTS : LIGHT_DEFAULTS);
+        if (nextDark) {
+            FlatDarkLaf.setup();
+        } else {
+            FlatLightLaf.setup();
+        }
+    }
+
+    private static Map<String, String> withShared(Map<String, String> themeDefaults) {
+        Map<String, String> merged = new HashMap<>(SHARED_DEFAULTS);
+        merged.putAll(themeDefaults);
+        return Map.copyOf(merged);
+    }
+
+    /**
+     * FlatLaf grows fonts and its own controls to the screen's DPI; every size the studio sets itself has to grow with them.
+     */
+    static int scale(int pixels) {
+        return Math.round(pixels * pixelScale);
+    }
+
+    static double scale(double pixels) {
+        return pixels * pixelScale;
+    }
+
+    static Dimension scaledSize(int width, int height) {
+        return new Dimension(scale(width), scale(height));
+    }
+
+    static Border emptyBorder(int top, int left, int bottom, int right) {
+        return BorderFactory.createEmptyBorder(scale(top), scale(left), scale(bottom), scale(right));
+    }
+
+    static Font font() {
+        return themeFont("defaultFont", Font.PLAIN, 13);
+    }
+
+    static Font smallFont() {
+        return themeFont("small.font", Font.PLAIN, 11);
+    }
+
+    static Font boldFont() {
+        return font().deriveFont(Font.BOLD);
+    }
+
+    static Font titleFont() {
+        return font().deriveFont(Font.BOLD, font().getSize2D() + 1F);
+    }
+
+    static Font sectionFont() {
+        return smallFont().deriveFont(Font.BOLD);
+    }
+
+    static Font monospacedFont() {
+        return themeFont("monospaced.font", Font.PLAIN, 12);
+    }
+
+    private static Font themeFont(String key, int fallbackStyle, int fallbackSize) {
+        Font font = UIManager.getFont(key);
+        return font != null ? font : new Font(Font.SANS_SERIF, fallbackStyle, fallbackSize);
+    }
+
+    enum Mode {
+        AUTO("Match system"),
+        LIGHT("Light"),
+        DARK("Dark");
+
+        private final String label;
+
+        Mode(String label) {
+            this.label = label;
+        }
+
+        String label() {
+            return label;
+        }
+
+        String settingName() {
+            return name().toLowerCase(Locale.ROOT);
+        }
+
+        static Mode fromSetting(String setting) {
+            for (Mode mode : values()) {
+                if (mode.settingName().equalsIgnoreCase(setting)) {
+                    return mode;
+                }
+            }
+            return AUTO;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/StudioToolbar.java

@@ -0,0 +1,144 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.formdev.flatlaf.FlatClientProperties;
+import com.formdev.flatlaf.icons.FlatSearchIcon;
+
+import javax.swing.BorderFactory;
+import javax.swing.ButtonGroup;
+import javax.swing.JButton;
+import javax.swing.JComponent;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JPopupMenu;
+import javax.swing.JRadioButtonMenuItem;
+import javax.swing.JScrollPane;
+import javax.swing.JTextField;
+import javax.swing.JToggleButton;
+import javax.swing.JToolBar;
+import javax.swing.ScrollPaneConstants;
+import java.awt.BorderLayout;
+import java.awt.Insets;
+
+/**
+ * Builds the IntelliJ style controls the studio windows share: a flat main toolbar, borderless toolbar buttons and search boxes.
+ */
+final class StudioToolbar {
+    private static final int TOOLBAR_HEIGHT_PADDING = 5;
+
+    private StudioToolbar() {
+    }
+
+    static JToolBar create() {
+        JToolBar toolbar = new JToolBar();
+        toolbar.setFloatable(false);
+        toolbar.setRollover(true);
+        toolbar.setBackground(StudioTheme.PANEL_BACKGROUND);
+        toolbar.setBorder(BorderFactory.createCompoundBorder(
+                BorderFactory.createMatteBorder(0, 0, 1, 0, StudioTheme.SEPARATOR),
+                StudioTheme.emptyBorder(TOOLBAR_HEIGHT_PADDING, 8, TOOLBAR_HEIGHT_PADDING, 8)
+        ));
+        return toolbar;
+    }
+
+    static JLabel label(String text) {
+        JLabel label = new JLabel(text);
+        label.setForeground(StudioTheme.SECONDARY_TEXT);
+        label.setBorder(StudioTheme.emptyBorder(0, 6, 0, 6));
+        return label;
+    }
+
+    static JButton button(String text, String tooltip, Runnable action) {
+        JButton button = toolbarButton(text, tooltip);
+        button.addActionListener(event -> action.run());
+        return button;
+    }
+
+    /**
+     * Opens a menu to pick light, dark or the system's theme.
+     */
+    static JButton themeButton() {
+        JButton button = toolbarButton("Theme", "Light, dark, or whatever the system uses");
+        button.addActionListener(event -> themeMenu().show(button, 0, button.getHeight()));
+        return button;
+    }
+
+    private static JPopupMenu themeMenu() {
+        JPopupMenu menu = new JPopupMenu();
+        ButtonGroup choices = new ButtonGroup();
+        StudioTheme.Mode current = StudioTheme.mode();
+        for (StudioTheme.Mode mode : StudioTheme.Mode.values()) {
+            JRadioButtonMenuItem item = new JRadioButtonMenuItem(mode.label(), mode == current);
+            item.addActionListener(event -> StudioTheme.choose(mode));
+            choices.add(item);
+            menu.add(item);
+        }
+        return menu;
+    }
+
+    private static JButton toolbarButton(String text, String tooltip) {
+        JButton button = new JButton(text);
+        button.setToolTipText(tooltip);
+        button.setFocusable(false);
+        button.setMargin(new Insets(4, 8, 4, 8));
+        button.putClientProperty(FlatClientProperties.BUTTON_TYPE, FlatClientProperties.BUTTON_TYPE_TOOLBAR_BUTTON);
+        return button;
+    }
+
+    static JToggleButton toggle(String text, String tooltip) {
+        JToggleButton toggle = new JToggleButton(text);
+        toggle.setToolTipText(tooltip);
+        toggle.setFocusable(false);
+        toggle.setMargin(new Insets(4, 8, 4, 8));
+        toggle.putClientProperty(FlatClientProperties.BUTTON_TYPE, FlatClientProperties.BUTTON_TYPE_TOOLBAR_BUTTON);
+        return toggle;
+    }
+
+    // An underlined tab like IntelliJ's tool window tabs.
+    static JToggleButton tab(String text) {
+        JToggleButton tab = new JToggleButton(text);
+        tab.setFocusable(false);
+        tab.putClientProperty(FlatClientProperties.BUTTON_TYPE, FlatClientProperties.BUTTON_TYPE_TAB);
+        return tab;
+    }
+
+    static void makeSearchField(JTextField field, String placeholder) {
+        field.putClientProperty(FlatClientProperties.PLACEHOLDER_TEXT, placeholder);
+        field.putClientProperty(FlatClientProperties.TEXT_FIELD_LEADING_ICON, new FlatSearchIcon());
+        field.putClientProperty(FlatClientProperties.TEXT_FIELD_SHOW_CLEAR_BUTTON, true);
+        field.setToolTipText(placeholder);
+    }
+
+    static JPanel padded(JComponent content, int top, int left, int bottom, int right) {
+        JPanel panel = new JPanel(new BorderLayout());
+        panel.setOpaque(false);
+        panel.setBorder(StudioTheme.emptyBorder(top, left, bottom, right));
+        panel.add(content, BorderLayout.CENTER);
+        return panel;
+    }
+
+    static JScrollPane scroll(JComponent content) {
+        JScrollPane scrollPane = new JScrollPane(content);
+        scrollPane.setBorder(BorderFactory.createEmptyBorder());
+        scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
+        scrollPane.getVerticalScrollBar().setUnitIncrement(18);
+        return scrollPane;
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/SystemAppearance.java

@@ -0,0 +1,110 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.Locale;
+import java.util.Optional;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Asks the operating system whether its user prefers dark or light apps, through the same settings desktop apps
+ * follow: the freedesktop portal or GNOME's setting on Linux, the apps theme on Windows, the appearance on macOS.
+ */
+final class SystemAppearance {
+    private static final long COMMAND_TIMEOUT_MILLIS = 2000L;
+    private static final String PORTAL_DARK = "uint32 1";
+    private static final String PORTAL_LIGHT = "uint32 2";
+
+    private SystemAppearance() {
+    }
+
+    /**
+     * Empty when the system has no preference or could not be asked.
+     */
+    static Optional<Boolean> prefersDark() {
+        String os = System.getProperty("os.name", "").toLowerCase(Locale.ROOT);
+        if (os.contains("win")) {
+            return windowsPrefersDark();
+        }
+        if (os.contains("mac")) {
+            return macPrefersDark();
+        }
+        return linuxPrefersDark();
+    }
+
+    private static Optional<Boolean> linuxPrefersDark() {
+        Optional<String> portal = output(List.of("gdbus", "call", "--session", "--dest", "org.freedesktop.portal.Desktop",
+                "--object-path", "/org/freedesktop/portal/desktop", "--method", "org.freedesktop.portal.Settings.ReadOne",
+                "org.freedesktop.appearance", "color-scheme"));
+        if (portal.filter(answer -> answer.contains(PORTAL_DARK)).isPresent()) {
+            return Optional.of(true);
+        }
+        if (portal.filter(answer -> answer.contains(PORTAL_LIGHT)).isPresent()) {
+            return Optional.of(false);
+        }
+        Optional<String> gnome = output(List.of("gsettings", "get", "org.gnome.desktop.interface", "color-scheme"));
+        if (gnome.filter(scheme -> scheme.contains("prefer-dark")).isPresent()) {
+            return Optional.of(true);
+        }
+        if (gnome.filter(scheme -> scheme.contains("prefer-light")).isPresent()) {
+            return Optional.of(false);
+        }
+        return output(List.of("gsettings", "get", "org.gnome.desktop.interface", "gtk-theme"))
+                .map(theme -> theme.toLowerCase(Locale.ROOT).contains("dark"));
+    }
+
+    private static Optional<Boolean> windowsPrefersDark() {
+        return output(List.of("reg", "query", "HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize",
+                "/v", "AppsUseLightTheme"))
+                .filter(answer -> answer.contains("AppsUseLightTheme"))
+                .map(answer -> answer.trim().endsWith("0x0"));
+    }
+
+    // The setting only exists while macOS is dark, so a failed read means light.
+    private static Optional<Boolean> macPrefersDark() {
+        return Optional.of(output(List.of("defaults", "read", "-g", "AppleInterfaceStyle"))
+                .filter(style -> style.trim().equalsIgnoreCase("dark"))
+                .isPresent());
+    }
+
+    private static Optional<String> output(List<String> command) {
+        try {
+            Process process = new ProcessBuilder(command).redirectErrorStream(true).start();
+            if (!process.waitFor(COMMAND_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)) {
+                process.destroyForcibly();
+                return Optional.empty();
+            }
+            if (process.exitValue() != 0) {
+                return Optional.empty();
+            }
+            try (InputStream stream = process.getInputStream()) {
+                return Optional.of(new String(stream.readAllBytes(), StandardCharsets.UTF_8));
+            }
+        } catch (IOException missingCommand) {
+            return Optional.empty();
+        } catch (InterruptedException interrupted) {
+            Thread.currentThread().interrupt();
+            return Optional.empty();
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/ThemeColor.java

@@ -0,0 +1,55 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import java.awt.Color;
+
+/**
+ * A colour with a light and a dark version that always answers with the one of the current theme, like IntelliJ's
+ * JBColor. Components keep the same colour object across a theme switch and simply paint in the other version.
+ */
+final class ThemeColor extends Color {
+    private static final long serialVersionUID = 2286435620386470207L;
+    private final Color light;
+    private final Color dark;
+
+    ThemeColor(int lightRgb, int darkRgb) {
+        this(new Color(lightRgb), new Color(darkRgb));
+    }
+
+    ThemeColor(Color light, Color dark) {
+        super(dark.getRGB(), true);
+        this.light = light;
+        this.dark = dark;
+    }
+
+    // Every other colour query of Color, and Java2D's painting, go through this one.
+    @Override
+    public int getRGB() {
+        return current().getRGB();
+    }
+
+    String toHtml() {
+        return String.format("#%06X", getRGB() & 0xFFFFFF);
+    }
+
+    private Color current() {
+        return StudioTheme.isDark() ? dark : light;
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/Transform.java

@@ -0,0 +1,107 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+/**
+ * An affine transform built up like Minecraft's pose stack: each step applies to points before the steps added
+ * earlier. Rotations follow the right-hand rule, the way Minecraft turns model parts.
+ */
+final class Transform {
+    static final Transform IDENTITY = new Transform(new double[]{1D, 0D, 0D, 0D, 1D, 0D, 0D, 0D, 1D}, Vec3.ZERO);
+
+    private final double[] matrix;
+    private final Vec3 translation;
+
+    private Transform(double[] matrix, Vec3 translation) {
+        this.matrix = matrix;
+        this.translation = translation;
+    }
+
+    Transform translate(double x, double y, double z) {
+        return then(new Transform(IDENTITY.matrix, new Vec3(x, y, z)));
+    }
+
+    Transform rotateX(double degrees) {
+        double cos = cosine(degrees);
+        double sin = sine(degrees);
+        return then(new Transform(new double[]{1D, 0D, 0D, 0D, cos, -sin, 0D, sin, cos}, Vec3.ZERO));
+    }
+
+    Transform rotateY(double degrees) {
+        double cos = cosine(degrees);
+        double sin = sine(degrees);
+        return then(new Transform(new double[]{cos, 0D, sin, 0D, 1D, 0D, -sin, 0D, cos}, Vec3.ZERO));
+    }
+
+    Transform rotateZ(double degrees) {
+        double cos = cosine(degrees);
+        double sin = sine(degrees);
+        return then(new Transform(new double[]{cos, -sin, 0D, sin, cos, 0D, 0D, 0D, 1D}, Vec3.ZERO));
+    }
+
+    Transform scale(double x, double y, double z) {
+        return then(new Transform(new double[]{x, 0D, 0D, 0D, y, 0D, 0D, 0D, z}, Vec3.ZERO));
+    }
+
+    /**
+     * This transform applied after {@code next}.
+     */
+    Transform then(Transform next) {
+        double[] product = new double[9];
+        for (int row = 0; row < 3; row++) {
+            for (int column = 0; column < 3; column++) {
+                product[row * 3 + column] = matrix[row * 3] * next.matrix[column]
+                        + matrix[row * 3 + 1] * next.matrix[3 + column]
+                        + matrix[row * 3 + 2] * next.matrix[6 + column];
+            }
+        }
+        return new Transform(product, direction(next.translation).plus(translation));
+    }
+
+    Vec3 point(Vec3 point) {
+        return direction(point).plus(translation);
+    }
+
+    Vec3 direction(Vec3 direction) {
+        return new Vec3(
+                matrix[0] * direction.x() + matrix[1] * direction.y() + matrix[2] * direction.z(),
+                matrix[3] * direction.x() + matrix[4] * direction.y() + matrix[5] * direction.z(),
+                matrix[6] * direction.x() + matrix[7] * direction.y() + matrix[8] * direction.z());
+    }
+
+    // Quarter turns stay exact, so faces turned by a blockstate still line up with the block's sides.
+    private static double cosine(double degrees) {
+        return sine(degrees + 90D);
+    }
+
+    private static double sine(double degrees) {
+        double turned = ((degrees % 360D) + 360D) % 360D;
+        if (turned == 0D || turned == 180D) {
+            return 0D;
+        }
+        if (turned == 90D) {
+            return 1D;
+        }
+        if (turned == 270D) {
+            return -1D;
+        }
+        return Math.sin(Math.toRadians(turned));
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/Vec3.java

@@ -0,0 +1,47 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+package com.volmit.iris.core.gui;
+
+/**
+ * A position or direction in a block, in block units.
+ */
+record Vec3(double x, double y, double z) {
+    static final Vec3 ZERO = new Vec3(0D, 0D, 0D);
+
+    Vec3 plus(Vec3 other) {
+        return new Vec3(x + other.x, y + other.y, z + other.z);
+    }
+
+    Vec3 minus(Vec3 other) {
+        return new Vec3(x - other.x, y - other.y, z - other.z);
+    }
+
+    Vec3 times(double factor) {
+        return new Vec3(x * factor, y * factor, z * factor);
+    }
+
+    double component(int axis) {
+        return switch (axis) {
+            case 0 -> x;
+            case 1 -> y;
+            default -> z;
+        };
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/VisionGUI.java

@@ -1,870 +0,0 @@
-/*
- * Iris is a World Generator for Minecraft Bukkit Servers
- * Copyright (c) 2022 Arcane Arts (Volmit Software)
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-
-package com.volmit.iris.core.gui;
-
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.gui.components.IrisRenderer;
-import com.volmit.iris.core.gui.components.RenderType;
-import com.volmit.iris.core.tools.IrisToolbelt;
-import com.volmit.iris.engine.IrisComplex;
-import com.volmit.iris.engine.framework.Engine;
-import com.volmit.iris.engine.object.IrisBiome;
-import com.volmit.iris.engine.object.IrisRegion;
-import com.volmit.iris.engine.object.IrisWorld;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.collection.KSet;
-import com.volmit.iris.util.format.Form;
-import com.volmit.iris.util.math.BlockPosition;
-import com.volmit.iris.util.math.M;
-import com.volmit.iris.util.math.RollingSequence;
-import com.volmit.iris.util.scheduling.ChronoLatch;
-import com.volmit.iris.util.scheduling.J;
-import com.volmit.iris.util.scheduling.O;
-import com.volmit.iris.util.scheduling.PrecisionStopwatch;
-import org.bukkit.Location;
-import org.bukkit.entity.LivingEntity;
-import org.bukkit.entity.Player;
-
-import javax.imageio.ImageIO;
-import javax.swing.*;
-import javax.swing.event.MouseInputListener;
-import java.awt.*;
-import java.awt.event.*;
-import java.awt.image.BufferedImage;
-import java.io.File;
-import java.io.IOException;
-import java.util.Locale;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
-import java.util.function.BiFunction;
-
-import static com.volmit.iris.util.data.registry.Attributes.MAX_HEALTH;
-
-public class VisionGUI extends JPanel implements MouseWheelListener, KeyListener, MouseMotionListener, MouseInputListener {
-    private static final long serialVersionUID = 2094606939770332040L;
-    private final KList<LivingEntity> lastEntities = new KList<>();
-    private final KMap<String, Long> notifications = new KMap<>();
-    private final ChronoLatch centities = new ChronoLatch(1000);
-    private final RollingSequence rs = new RollingSequence(512);
-    private final O<Integer> m = new O<>();
-    private final KMap<BlockPosition, BufferedImage> positions = new KMap<>();
-    private final KMap<BlockPosition, BufferedImage> fastpositions = new KMap<>();
-    private final KSet<BlockPosition> working = new KSet<>();
-    private final KSet<BlockPosition> workingfast = new KSet<>();
-    double tfps = 240D;
-    int ltc = 3;
-    private RenderType currentType = RenderType.BIOME;
-    private boolean help = true;
-    private boolean helpIgnored = false;
-    private boolean shift = false;
-    private Player player = null;
-    private boolean debug = false;
-    private boolean control = false;
-    private boolean eco = false;
-    private boolean lowtile = false;
-    private boolean follow = false;
-    private boolean alt = false;
-    private IrisRenderer renderer;
-    private IrisWorld world;
-    private double velocity = 0;
-    private int lowq = 12;
-    private double scale = 128;
-    private double mscale = 4D;
-    private int w = 0;
-    private int h = 0;
-    private double lx = 0;
-    private double lz = 0;
-    private double ox = 0;
-    private double oz = 0;
-    private double hx = 0;
-    private double hz = 0;
-    private double oxp = 0;
-    private double ozp = 0;
-    private Engine engine;
-    private int tid = 0;
-    private final ExecutorService e = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors(), r -> {
-        tid++;
-        Thread t = new Thread(r);
-        t.setName("Iris HD Renderer " + tid);
-        t.setPriority(Thread.MIN_PRIORITY);
-        t.setUncaughtExceptionHandler((et, e) ->
-        {
-            Iris.info("Exception encountered in " + et.getName());
-            e.printStackTrace();
-        });
-
-        return t;
-    });
-
-    private final ExecutorService eh = Executors.newFixedThreadPool(ltc, r -> {
-        tid++;
-        Thread t = new Thread(r);
-        t.setName("Iris Renderer " + tid);
-        t.setPriority(Thread.NORM_PRIORITY);
-        t.setUncaughtExceptionHandler((et, e) ->
-        {
-            Iris.info("Exception encountered in " + et.getName());
-            e.printStackTrace();
-        });
-
-        return t;
-    });
-    private BufferedImage texture;
-
-    public VisionGUI(JFrame frame) {
-        m.set(8);
-        rs.put(1);
-        addMouseWheelListener(this);
-        addMouseMotionListener(this);
-        addMouseListener(this);
-        frame.addKeyListener(this);
-        J.a(() -> {
-            J.sleep(10000);
-
-            if (!helpIgnored && help) {
-                help = false;
-            }
-        });
-        frame.addWindowListener(new java.awt.event.WindowAdapter() {
-            @Override
-            public void windowClosing(java.awt.event.WindowEvent windowEvent) {
-                e.shutdown();
-                eh.shutdown();
-            }
-        });
-    }
-
-    private static void createAndShowGUI(Engine r, int s, IrisWorld world) {
-        JFrame frame = new JFrame("Vision");
-        VisionGUI nv = new VisionGUI(frame);
-        nv.world = world;
-        nv.engine = r;
-        nv.renderer = new IrisRenderer(r);
-        frame.add(nv);
-        frame.setSize(1440, 820);
-        frame.setVisible(true);
-        File file = Iris.getCached("Iris Icon", "https://raw.githubusercontent.com/VolmitSoftware/Iris/master/icon.png");
-
-        if (file != null) {
-            try {
-                nv.texture = ImageIO.read(file);
-                frame.setIconImage(ImageIO.read(file));
-            } catch (IOException e) {
-                Iris.reportError(e);
-
-            }
-        }
-    }
-
-    public static void launch(Engine g, int i) {
-        J.a(() ->
-                createAndShowGUI(g, i, g.getWorld()));
-    }
-
-    public boolean updateEngine() {
-        if (engine.isClosed()) {
-            if (world.hasRealWorld()) {
-                try {
-                    engine = IrisToolbelt.access(world.realWorld()).getEngine();
-                    return !engine.isClosed();
-                } catch (Throwable e) {
-
-                }
-            }
-        }
-
-        return false;
-    }
-
-    @Override
-    public void mouseMoved(MouseEvent e) {
-        Point cp = e.getPoint();
-        lx = (cp.getX());
-        lz = (cp.getY());
-    }
-
-    @Override
-    public void mouseDragged(MouseEvent e) {
-        Point cp = e.getPoint();
-        ox += (lx - cp.getX()) * scale;
-        oz += (lz - cp.getY()) * scale;
-        lx = cp.getX();
-        lz = cp.getY();
-    }
-
-    public int getColor(double wx, double wz) {
-        BiFunction<Double, Double, Integer> colorFunction = (d, dx) -> Color.black.getRGB();
-
-        switch (currentType) {
-            case BIOME, DECORATOR_LOAD, OBJECT_LOAD, LAYER_LOAD ->
-                    colorFunction = (x, z) -> engine.getComplex().getTrueBiomeStream().get(x, z).getColor(engine, currentType).getRGB();
-            case BIOME_LAND ->
-                    colorFunction = (x, z) -> engine.getComplex().getLandBiomeStream().get(x, z).getColor(engine, currentType).getRGB();
-            case BIOME_SEA ->
-                    colorFunction = (x, z) -> engine.getComplex().getSeaBiomeStream().get(x, z).getColor(engine, currentType).getRGB();
-            case REGION ->
-                    colorFunction = (x, z) -> engine.getComplex().getRegionStream().get(x, z).getColor(engine.getComplex(), currentType).getRGB();
-            case CAVE_LAND ->
-                    colorFunction = (x, z) -> engine.getComplex().getCaveBiomeStream().get(x, z).getColor(engine, currentType).getRGB();
-            case HEIGHT ->
-                    colorFunction = (x, z) -> Color.getHSBColor(engine.getComplex().getHeightStream().get(x, z).floatValue(), 100, 100).getRGB();
-        }
-
-        return colorFunction.apply(wx, wz);
-    }
-
-    public void notify(String s) {
-        notifications.put(s, M.ms() + 2500);
-    }
-
-    @Override
-    public void keyTyped(KeyEvent e) {
-
-    }
-
-    @Override
-    public void keyPressed(KeyEvent e) {
-        if (e.getKeyCode() == KeyEvent.VK_SHIFT) {
-            shift = true;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_CONTROL) {
-            control = true;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_SEMICOLON) {
-            debug = true;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_SLASH) {
-            help = true;
-            helpIgnored = true;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_ALT) {
-            alt = true;
-        }
-    }
-
-    @Override
-    public void keyReleased(KeyEvent e) {
-        if (e.getKeyCode() == KeyEvent.VK_SEMICOLON) {
-            debug = false;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_SHIFT) {
-            shift = false;
-        }
-
-        if (e.getKeyCode() == KeyEvent.VK_CONTROL) {
-            control = false;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_SLASH) {
-            help = false;
-            helpIgnored = true;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_ALT) {
-            alt = false;
-        }
-
-        // Pushes
-        if (e.getKeyCode() == KeyEvent.VK_F) {
-            follow = !follow;
-
-            if (player != null && follow) {
-                notify("Following " + player.getName() + ". Press F to disable");
-            } else if (follow) {
-                notify("Can't follow, no one is in the world");
-                follow = false;
-            } else {
-                notify("Follow Off");
-            }
-
-            return;
-        }
-
-        if (e.getKeyCode() == KeyEvent.VK_R) {
-            dump();
-            notify("Refreshing Chunks");
-            return;
-        }
-
-        if (e.getKeyCode() == KeyEvent.VK_P) {
-            lowtile = !lowtile;
-            dump();
-            notify("Rendering " + (lowtile ? "Low" : "High") + " Quality Tiles");
-            return;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_E) {
-            eco = !eco;
-            dump();
-            notify("Using " + (eco ? "60" : "Uncapped") + " FPS Limit");
-            return;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_EQUALS) {
-            mscale = mscale + ((0.044 * mscale) * -3);
-            mscale = Math.max(mscale, 0.00001);
-            dump();
-            return;
-        }
-        if (e.getKeyCode() == KeyEvent.VK_MINUS) {
-            mscale = mscale + ((0.044 * mscale) * 3);
-            mscale = Math.max(mscale, 0.00001);
-            dump();
-            return;
-        }
-
-        if (e.getKeyCode() == KeyEvent.VK_BACK_SLASH) {
-            mscale = 1D;
-            dump();
-            notify("Zoom Reset");
-            return;
-        }
-
-        int currentMode = currentType.ordinal();
-
-        for (RenderType i : RenderType.values()) {
-            if (e.getKeyChar() == String.valueOf(i.ordinal() + 1).charAt(0)) {
-                if (i.ordinal() != currentMode) {
-                    currentType = i;
-                    dump();
-                    notify("Rendering " + Form.capitalizeWords(currentType.name().toLowerCase().replaceAll("\\Q_\\E", " ")));
-                    return;
-                }
-            }
-        }
-
-        if (e.getKeyCode() == KeyEvent.VK_M) {
-            currentType = RenderType.values()[(currentMode + 1) % RenderType.values().length];
-            notify("Rendering " + Form.capitalizeWords(currentType.name().toLowerCase().replaceAll("\\Q_\\E", " ")));
-            dump();
-        }
-    }
-
-    private void dump() {
-        positions.clear();
-        fastpositions.clear();
-    }
-
-    public BufferedImage getTile(KSet<BlockPosition> fg, int div, int x, int z, O<Integer> m) {
-        BlockPosition key = new BlockPosition((int) mscale, Math.floorDiv(x, div), Math.floorDiv(z, div));
-        fg.add(key);
-
-        if (positions.containsKey(key)) {
-            return positions.get(key);
-        }
-
-        if (fastpositions.containsKey(key)) {
-            if (!working.contains(key) && working.size() < 9) {
-                m.set(m.get() - 1);
-
-                if (m.get() >= 0 && velocity < 50) {
-                    working.add(key);
-                    double mk = mscale;
-                    double mkd = scale;
-                    e.submit(() ->
-                    {
-                        PrecisionStopwatch ps = PrecisionStopwatch.start();
-                        BufferedImage b = renderer.render(x * mscale, z * mscale, div * mscale, div / (lowtile ? 3 : 1), currentType);
-                        rs.put(ps.getMilliseconds());
-                        working.remove(key);
-
-                        if (mk == mscale && mkd == scale) {
-                            positions.put(key, b);
-                        }
-                    });
-                }
-            }
-
-            return fastpositions.get(key);
-        }
-
-        if (workingfast.contains(key) || workingfast.size() > Runtime.getRuntime().availableProcessors()) {
-            return null;
-        }
-
-        workingfast.add(key);
-        double mk = mscale;
-        double mkd = scale;
-        eh.submit(() ->
-        {
-            PrecisionStopwatch ps = PrecisionStopwatch.start();
-            BufferedImage b = renderer.render(x * mscale, z * mscale, div * mscale, div / lowq, currentType);
-            rs.put(ps.getMilliseconds());
-            workingfast.remove(key);
-
-            if (mk == mscale && mkd == scale) {
-                fastpositions.put(key, b);
-            }
-        });
-        return null;
-    }
-
-    private double getWorldX(double screenX) {
-        return (mscale * screenX) + ((oxp / scale) * mscale);
-    }
-
-    private double getWorldZ(double screenZ) {
-        return (mscale * screenZ) + ((ozp / scale) * mscale);
-    }
-
-    private double getScreenX(double x) {
-        return (x / mscale) - ((oxp / scale));
-    }
-
-    private double getScreenZ(double z) {
-        return (z / mscale) - ((ozp / scale));
-    }
-
-    @Override
-    public void paint(Graphics gx) {
-
-        if (engine.isClosed()) {
-            EventQueue.invokeLater(() -> {
-                try {
-                    setVisible(false);
-                } catch (Throwable e) {
-
-                }
-            });
-
-            return;
-        }
-
-        if (updateEngine()) {
-            dump();
-        }
-
-        if (ox < oxp) {
-            velocity = Math.abs(ox - oxp) * 0.36;
-            oxp -= velocity;
-        }
-
-        if (ox > oxp) {
-            velocity = Math.abs(oxp - ox) * 0.36;
-            oxp += velocity;
-        }
-
-        if (oz < ozp) {
-            velocity = Math.abs(oz - ozp) * 0.36;
-            ozp -= velocity;
-        }
-
-        if (oz > ozp) {
-            velocity = Math.abs(ozp - oz) * 0.36;
-            ozp += velocity;
-        }
-
-        if (lx < hx) {
-            hx -= Math.abs(lx - hx) * 0.36;
-        }
-
-        if (lx > hx) {
-            hx += Math.abs(hx - lx) * 0.36;
-        }
-
-        if (lz < hz) {
-            hz -= Math.abs(lz - hz) * 0.36;
-        }
-
-        if (lz > hz) {
-            hz += Math.abs(hz - lz) * 0.36;
-        }
-
-        if (Math.abs(lx - hx) < 0.5) {
-            hx = lx;
-        }
-        if (Math.abs(lz - hz) < 0.5) {
-            hz = lz;
-        }
-
-        if (centities.flip()) {
-            J.s(() -> {
-                synchronized (lastEntities) {
-                    lastEntities.clear();
-                    lastEntities.addAll(world.getEntitiesByClass(LivingEntity.class));
-                }
-            });
-        }
-        lowq = Math.max(Math.min((int) M.lerp(8, 28, velocity / 1000D), 28), 8);
-        PrecisionStopwatch p = PrecisionStopwatch.start();
-        Graphics2D g = (Graphics2D) gx;
-        w = getWidth();
-        h = getHeight();
-        double vscale = scale;
-        scale = w / 12D;
-
-        if (scale != vscale) {
-            positions.clear();
-        }
-
-        KSet<BlockPosition> gg = new KSet<>();
-        int iscale = (int) scale;
-        g.setColor(Color.white);
-        g.clearRect(0, 0, w, h);
-        double offsetX = oxp / scale;
-        double offsetZ = ozp / scale;
-        m.set(3);
-
-        for (int r = 0; r < Math.max(w, h); r += iscale) {
-            for (int i = -iscale; i < w + iscale; i += iscale) {
-                for (int j = -iscale; j < h + iscale; j += iscale) {
-                    int a = i - (w / 2);
-                    int b = j - (h / 2);
-                    if (a * a + b * b <= r * r) {
-                        int tx = (int) (Math.floor((offsetX + i) / iscale) * iscale);
-                        int tz = (int) (Math.floor((offsetZ + j) / iscale) * iscale);
-                        BufferedImage t = getTile(gg, iscale, tx, tz, m);
-
-                        if (t != null) {
-                            int rx = Math.floorMod((int) Math.floor(offsetX), iscale);
-                            int rz = Math.floorMod((int) Math.floor(offsetZ), iscale);
-                            g.drawImage(t, i - rx, j - rz, iscale, iscale, (img, infoflags, x, y, width, height) -> true);
-                        }
-                    }
-                }
-            }
-        }
-
-        p.end();
-
-        for (BlockPosition i : positions.k()) {
-            if (!gg.contains(i)) {
-                positions.remove(i);
-            }
-        }
-
-        hanleFollow();
-        renderOverlays(g);
-
-        if (!isVisible()) {
-            return;
-        }
-
-        if (!getParent().isVisible()) {
-            return;
-        }
-
-        if (!getParent().getParent().isVisible()) {
-            return;
-        }
-
-        J.a(() ->
-        {
-            J.sleep(eco ? 15 : 1);
-            repaint();
-        });
-    }
-
-    private void hanleFollow() {
-        if (follow && player != null) {
-            animateTo(player.getLocation().getX(), player.getLocation().getZ());
-        }
-    }
-
-    private void renderOverlays(Graphics2D g) {
-        renderPlayer(g);
-
-        if (help) {
-            renderOverlayHelp(g);
-        } else if (debug) {
-            renderOverlayDebug(g);
-        }
-
-        renderOverlayLegend(g);
-
-        renderHoverOverlay(g, shift);
-        if (!notifications.isEmpty()) {
-            renderNotification(g);
-        }
-    }
-
-    private void renderOverlayLegend(Graphics2D g) {
-        KList<String> l = new KList<>();
-        l.add("Zoom: " + Form.pc(mscale, 0));
-        l.add("Blocks: " + Form.f((int) mscale * w) + " by " + Form.f((int) mscale * h));
-        l.add("BPP: " + Form.f(mscale, 1));
-        l.add("Render Mode: " + Form.capitalizeWords(currentType.name().toLowerCase().replaceAll("\\Q_\\E", " ")));
-
-        drawCardBR(g, l);
-    }
-
-    private void renderNotification(Graphics2D g) {
-        drawCardCB(g, notifications.k());
-
-        for (String i : notifications.k()) {
-            if (M.ms() > notifications.get(i)) {
-                notifications.remove(i);
-            }
-        }
-    }
-
-    private void renderPlayer(Graphics2D g) {
-        Player b = null;
-
-        for (Player i : world.getPlayers()) {
-            b = i;
-            renderPosition(g, i.getLocation().getX(), i.getLocation().getZ());
-        }
-
-        synchronized (lastEntities) {
-            double dist = Double.MAX_VALUE;
-            LivingEntity h = null;
-
-            for (LivingEntity i : lastEntities) {
-                if (i instanceof Player) {
-                    continue;
-                }
-
-                renderMobPosition(g, i, i.getLocation().getX(), i.getLocation().getZ());
-                if (shift) {
-                    double d = i.getLocation().distanceSquared(new Location(i.getWorld(), getWorldX(hx), i.getLocation().getY(), getWorldZ(hz)));
-
-                    if (d < dist) {
-                        dist = d;
-                        h = i;
-                    }
-                }
-            }
-
-            if (h != null && shift) {
-                g.setColor(Color.red);
-                g.fillRoundRect((int) getScreenX(h.getLocation().getX()) - 10, (int) getScreenZ(h.getLocation().getZ()) - 10, 20, 20, 20, 20);
-                KList<String> k = new KList<>();
-                k.add(Form.capitalizeWords(h.getType().name().toLowerCase(Locale.ROOT).replaceAll("\\Q_\\E", " ")) + h.getEntityId());
-
-                k.add("Pos: " + h.getLocation().getBlockX() + ", " + h.getLocation().getBlockY() + ", " + h.getLocation().getBlockZ());
-                k.add("UUID: " + h.getUniqueId());
-                k.add("HP: " + h.getHealth() + " / " + h.getAttribute(MAX_HEALTH).getValue());
-
-                drawCardTR(g, k);
-            }
-        }
-
-        player = b;
-    }
-
-    private void animateTo(double wx, double wz) {
-        double cx = getWorldX(getWidth() / 2);
-        double cz = getWorldZ(getHeight() / 2);
-        ox += ((wx - cx) / mscale) * scale;
-        oz += ((wz - cz) / mscale) * scale;
-    }
-
-    private void renderPosition(Graphics2D g, double x, double z) {
-        if (texture != null) {
-            g.drawImage(texture, (int) getScreenX(x), (int) getScreenZ(z), 66, 66, (img, infoflags, xx, xy, width, height) -> true);
-        } else {
-            g.setColor(Color.darkGray);
-            g.fillRoundRect((int) getScreenX(x) - 15, (int) getScreenZ(z) - 15, 30, 30, 15, 15);
-            g.setColor(Color.cyan.darker().darker());
-            g.fillRoundRect((int) getScreenX(x) - 10, (int) getScreenZ(z) - 10, 20, 20, 10, 10);
-        }
-    }
-
-    private void renderMobPosition(Graphics2D g, LivingEntity e, double x, double z) {
-        g.setColor(Color.red.darker().darker());
-        g.fillRoundRect((int) getScreenX(x) - 2, (int) getScreenZ(z) - 2, 4, 4, 4, 4);
-    }
-
-    private void renderHoverOverlay(Graphics2D g, boolean detailed) {
-        IrisBiome biome = engine.getComplex().getTrueBiomeStream().get(getWorldX(hx), getWorldZ(hz));
-        IrisRegion region = engine.getComplex().getRegionStream().get(getWorldX(hx), getWorldZ(hz));
-        KList<String> l = new KList<>();
-        l.add("Biome: " + biome.getName());
-        l.add("Region: " + region.getName() + "(" + region.getLoadKey() + ")");
-        l.add("Block " + (int) getWorldX(hx) + ", " + (int) getWorldZ(hz));
-        if (detailed) {
-            l.add("Chunk " + ((int) getWorldX(hx) >> 4) + ", " + ((int) getWorldZ(hz) >> 4));
-            l.add("Region " + (((int) getWorldX(hx) >> 4) >> 5) + ", " + (((int) getWorldZ(hz) >> 4) >> 5));
-            l.add("Key: " + biome.getLoadKey());
-            l.add("File: " + biome.getLoadFile());
-        }
-
-        drawCardAt((float) hx, (float) hz, 0, 0, g, l);
-    }
-
-    private void renderOverlayDebug(Graphics2D g) {
-        KList<String> l = new KList<>();
-        l.add("Velocity: " + (int) velocity);
-        l.add("Center Pos: " + Form.f((int) getWorldX(getWidth() / 2)) + ", " + Form.f((int) getWorldZ(getHeight() / 2)));
-        drawCardBL(g, l);
-    }
-
-    private void renderOverlayHelp(Graphics2D g) {
-        KList<String> l = new KList<>();
-        l.add("/ to show this help screen");
-        l.add("R to repaint the screen");
-        l.add("F to follow first player");
-        l.add("+/- to Change Zoom");
-        l.add("\\ to reset zoom to 1");
-        l.add("M to cycle render modes");
-        l.add("P to toggle Tile Quality Mode");
-        l.add("E to toggle Eco FPS Mode");
-
-        int ff = 0;
-        for (RenderType i : RenderType.values()) {
-            ff++;
-            l.add(ff + " to view " + Form.capitalizeWords(i.name().toLowerCase().replaceAll("\\Q_\\E", " ")));
-        }
-
-        l.add("Shift for additional biome details (at cursor)");
-        l.add("CTRL + Click to teleport to location");
-        l.add("ALT + Click to open biome in VSCode");
-        drawCardTL(g, l);
-    }
-
-    private void drawCardTL(Graphics2D g, KList<String> text) {
-        drawCardAt(0, 0, 0, 0, g, text);
-    }
-
-    private void drawCardBR(Graphics2D g, KList<String> text) {
-        drawCardAt(getWidth(), getHeight(), 1, 1, g, text);
-    }
-
-    private void drawCardBL(Graphics2D g, KList<String> text) {
-        drawCardAt(0, getHeight(), 0, 1, g, text);
-    }
-
-    private void drawCardTR(Graphics2D g, KList<String> text) {
-        drawCardAt(getWidth(), 0, 1, 0, g, text);
-    }
-
-    private void open() {
-        IrisComplex complex = engine.getComplex();
-        File r = null;
-        switch (currentType) {
-            case BIOME, LAYER_LOAD, DECORATOR_LOAD, OBJECT_LOAD, HEIGHT ->
-                    r = complex.getTrueBiomeStream().get(getWorldX(hx), getWorldZ(hz)).openInVSCode();
-            case BIOME_LAND -> r = complex.getLandBiomeStream().get(getWorldX(hx), getWorldZ(hz)).openInVSCode();
-            case BIOME_SEA -> r = complex.getSeaBiomeStream().get(getWorldX(hx), getWorldZ(hz)).openInVSCode();
-            case REGION -> r = complex.getRegionStream().get(getWorldX(hx), getWorldZ(hz)).openInVSCode();
-            case CAVE_LAND -> r = complex.getCaveBiomeStream().get(getWorldX(hx), getWorldZ(hz)).openInVSCode();
-        }
-
-        notify("Opening " + r.getPath() + " in VSCode");
-    }
-
-    private void teleport() {
-        J.s(() -> {
-            if (player != null) {
-                int xx = (int) getWorldX(hx);
-                int zz = (int) getWorldZ(hz);
-                int h = engine.getComplex().getRoundedHeighteightStream().get(xx, zz);
-                player.teleport(new Location(player.getWorld(), xx, h, zz));
-                notify("Teleporting to " + xx + ", " + h + ", " + zz);
-            } else {
-                notify("No player in world, can't teleport.");
-            }
-        });
-    }
-
-    private void drawCardCB(Graphics2D g, KList<String> text) {
-        drawCardAt(getWidth() / 2, getHeight(), 0.5, 1, g, text);
-    }
-
-    private void drawCardCT(Graphics2D g, KList<String> text) {
-        drawCardAt(getWidth() / 2, 0, 0.5, 0, g, text);
-    }
-
-    private void drawCardAt(float x, float y, double pushX, double pushZ, Graphics2D g, KList<String> text) {
-        g.setFont(new Font("Hevetica", Font.BOLD, 16));
-        int h = 0;
-        int w = 0;
-
-        for (String i : text) {
-            h += g.getFontMetrics().getHeight();
-            w = Math.max(w, g.getFontMetrics().stringWidth(i));
-        }
-
-        w += 28;
-        h += 14;
-
-        int cw = (int) ((w + 26) * pushX);
-        int ch = (int) ((h + 26) * pushZ);
-
-        g.setColor(Color.darkGray);
-        g.fillRect((int) x + 7 + 2 - cw, (int) y + 12 + 2 - ch, w + 7, h); // Shadow
-        g.setColor(Color.gray);
-        g.fillRect((int) x + 7 + 1 - cw, (int) y + 12 + 1 - ch, w + 7, h); // Shadow
-        g.setColor(Color.white);
-        g.fillRect((int) x + 7 - cw, (int) y + 12 - ch, w + 7, h);
-
-        g.setColor(Color.black);
-        int m = 0;
-        for (String i : text) {
-            g.drawString(i, x + 14 - cw, y + 14 - ch + (++m * g.getFontMetrics().getHeight()));
-        }
-    }
-
-    public void mouseWheelMoved(MouseWheelEvent e) {
-        int notches = e.getWheelRotation();
-        if (e.isControlDown()) {
-            return;
-        }
-
-        double m0 = mscale;
-        double m1 = m0 + ((0.25 * m0) * notches);
-        m1 = Math.max(m1, 0.00001);
-        if (m1 == m0) {
-            return;
-        }
-
-        positions.clear();
-        fastpositions.clear();
-
-        Point p = e.getPoint();
-        double sx = p.getX();
-        double sz = p.getY();
-
-        double newOxp = scale * ((m0 / m1) * (sx + (oxp / scale)) - sx);
-        double newOzp = scale * ((m0 / m1) * (sz + (ozp / scale)) - sz);
-
-        mscale = m1;
-        oxp = newOxp;
-        ozp = newOzp;
-        ox = oxp;
-        oz = ozp;
-    }
-
-    @Override
-    public void mouseClicked(MouseEvent e) {
-        if (control) {
-            teleport();
-        } else if (alt) {
-            open();
-        }
-    }
-
-    @Override
-    public void mousePressed(MouseEvent e) {
-
-    }
-
-    @Override
-    public void mouseReleased(MouseEvent e) {
-
-    }
-
-    @Override
-    public void mouseEntered(MouseEvent e) {
-
-    }
-
-    @Override
-    public void mouseExited(MouseEvent e) {
-
-    }
-}

core/src/main/java/com/volmit/iris/core/gui/VisionOverlay.java

@@ -0,0 +1,180 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.gui.components.MapLayer;
+import com.volmit.iris.engine.IrisComplex;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisRegion;
+import com.volmit.iris.engine.object.IrisWorld;
+import com.volmit.iris.util.format.Form;
+import com.volmit.iris.util.scheduling.J;
+import org.bukkit.Location;
+import org.bukkit.World;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.entity.Player;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+import java.util.Optional;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.function.Consumer;
+
+import static com.volmit.iris.util.data.registry.Attributes.MAX_HEALTH;
+
+final class VisionOverlay {
+    private final Engine engine;
+    private final UUID openerId;
+    private final AtomicBoolean playerRefreshQueued = new AtomicBoolean();
+    private volatile List<GuiMarker> playerMarkers = List.of();
+
+    VisionOverlay(Engine engine, UUID openerId) {
+        this.engine = engine;
+        this.openerId = openerId;
+    }
+
+    List<GuiMarker> lastKnownPlayers() {
+        queuePlayerRefresh();
+        return playerMarkers;
+    }
+
+    void requestEntities(Consumer<List<GuiMarker>> sink) {
+        runOnServerThread(() -> sink.accept(collectEntities()));
+    }
+
+    void teleport(int blockX, int blockZ) {
+        runOnServerThread(() -> teleportOpener(blockX, blockZ));
+    }
+
+    Optional<String> openInEditor(double worldX, double worldZ, MapLayer layer) {
+        IrisComplex complex = engine.getComplex();
+        File file = switch (layer.type()) {
+            case BIOME, HEIGHT ->
+                    complex.getTrueBiomeStream().get(worldX, worldZ).openInVSCode();
+            case BIOME_LAND -> complex.getLandBiomeStream().get(worldX, worldZ).openInVSCode();
+            case BIOME_SEA -> complex.getSeaBiomeStream().get(worldX, worldZ).openInVSCode();
+            case REGION -> complex.getRegionStream().get(worldX, worldZ).openInVSCode();
+            case REGION_PREVIEW -> openPreviewedBiome(complex, layer.previewRegionKey(), worldX, worldZ);
+            case CAVE_LAND -> complex.getCaveBiomeStream().get(worldX, worldZ).openInVSCode();
+            case CONTINENT -> null;
+        };
+        return Optional.ofNullable(file).map(File::getName);
+    }
+
+    private File openPreviewedBiome(IrisComplex complex, String regionKey, double worldX, double worldZ) {
+        IrisRegion region = engine.getData().getRegionLoader().load(regionKey);
+        return region == null ? null : complex.surfaceBiomeAsIfIn(region, worldX, worldZ).openInVSCode();
+    }
+
+    private void queuePlayerRefresh() {
+        if (!playerRefreshQueued.compareAndSet(false, true)) {
+            return;
+        }
+
+        boolean scheduled = runOnServerThread(() -> {
+            try {
+                playerMarkers = collectPlayers();
+            } finally {
+                playerRefreshQueued.set(false);
+            }
+        });
+        if (!scheduled) {
+            playerRefreshQueued.set(false);
+        }
+    }
+
+    private List<GuiMarker> collectPlayers() {
+        List<GuiMarker> markers = new ArrayList<>();
+        for (Player player : engine.getWorld().getPlayers()) {
+            Location at = player.getLocation();
+            markers.add(GuiMarker.player(player.getName(), at.getX(), at.getZ()));
+        }
+        return List.copyOf(markers);
+    }
+
+    private List<GuiMarker> collectEntities() {
+        IrisWorld world = engine.getWorld();
+        if (!world.hasRealWorld()) {
+            return List.of();
+        }
+
+        List<GuiMarker> markers = new ArrayList<>();
+        for (LivingEntity entity : world.getEntitiesByClass(LivingEntity.class)) {
+            if (!(entity instanceof Player)) {
+                markers.add(marker(entity));
+            }
+        }
+        return List.copyOf(markers);
+    }
+
+    private static GuiMarker marker(LivingEntity entity) {
+        Location at = entity.getLocation();
+        String label = Form.capitalizeWords(entity.getType().name().toLowerCase(Locale.ROOT).replace('_', ' '));
+        double maxHealth = 0D;
+        try {
+            maxHealth = entity.getAttribute(MAX_HEALTH).getValue();
+        } catch (Throwable ignored) {
+        }
+        return GuiMarker.entity(label, at.getX(), at.getY(), at.getZ(), entity.getHealth(), maxHealth);
+    }
+
+    private void teleportOpener(int blockX, int blockZ) {
+        IrisWorld target = engine.getWorld();
+        Player player = selectPlayer(target.getPlayers());
+        if (player == null || !target.hasRealWorld() || engine.isClosed()) {
+            return;
+        }
+
+        World world = target.realWorld();
+        int blockY = engine.getMinHeight() + engine.getHeight(blockX, blockZ, false) + 2;
+        Location destination = new Location(world, blockX + 0.5D, blockY, blockZ + 0.5D);
+        player.teleportAsync(destination).whenComplete((success, failure) -> {
+            if (failure != null) {
+                Iris.reportError(failure);
+                Iris.warn("Vision could not teleport %s to %d, %d.", player.getName(), blockX, blockZ);
+            }
+        });
+    }
+
+    private Player selectPlayer(List<Player> players) {
+        if (openerId == null) {
+            return players.isEmpty() ? null : players.get(0);
+        }
+        for (Player player : players) {
+            if (openerId.equals(player.getUniqueId())) {
+                return player;
+            }
+        }
+        return null;
+    }
+
+    private static boolean runOnServerThread(Runnable task) {
+        try {
+            J.s(task);
+            return true;
+        } catch (Throwable e) {
+            Iris.reportError(e);
+            return false;
+        }
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/VisionRenderController.java

@@ -0,0 +1,649 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.gui.components.IrisRenderer;
+import com.volmit.iris.core.gui.components.MapLabels;
+import com.volmit.iris.core.gui.components.MapLayer;
+import com.volmit.iris.core.gui.components.MapTile;
+
+import java.awt.EventQueue;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.Callable;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.RejectedExecutionException;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Consumer;
+
+/**
+ * Renders the map as tiles on fixed zoom levels, so zooming within a level and panning reuse tiles that are already drawn.
+ * Tiles keep rendering while the view moves, as long as they are still on screen.
+ */
+final class VisionRenderController implements AutoCloseable {
+    static final int TILE_PIXELS = 64;
+    static final double MINIMUM_VIEW_BLOCKS_PER_PIXEL = 1D / 8D;
+    static final double MAXIMUM_BLOCKS_PER_PIXEL = 4_096D;
+
+    private static final double MINIMUM_RENDER_BLOCKS_PER_PIXEL = 1D;
+    private static final int MAXIMUM_VISIBLE_TILES = 32_768;
+    private static final int PROBE_QUEUE_CAPACITY = 1;
+    private static final int COARSER_FALLBACK_LEVELS = 6;
+    private static final long CACHE_BYTES = 256L * 1024L * 1024L;
+
+    private final Runnable listener;
+    private final int workerCount;
+    private final ThreadPoolExecutor renderExecutor;
+    private final ThreadPoolExecutor probeExecutor;
+    private final WeightedTileCache cache;
+    private final Set<TileKey> tilesInFlight = new HashSet<>();
+    private final AtomicInteger activeWorkers = new AtomicInteger();
+    private final AtomicLong viewSequence = new AtomicLong();
+    private final AtomicLong probeSequence = new AtomicLong();
+    private final AtomicBoolean closed = new AtomicBoolean();
+    private final AtomicBoolean publicationQueued = new AtomicBoolean();
+    private final AtomicBoolean publicationDirty = new AtomicBoolean();
+    private volatile Frame currentFrame;
+
+    VisionRenderController(Runnable listener) {
+        this.listener = Objects.requireNonNull(listener, "listener");
+        int processors = Math.max(1, Runtime.getRuntime().availableProcessors());
+        this.workerCount = Math.max(1, Math.min(6, processors / 2));
+        AtomicInteger threadSequence = new AtomicInteger();
+        this.renderExecutor = new ThreadPoolExecutor(
+                workerCount,
+                workerCount,
+                30L,
+                TimeUnit.SECONDS,
+                new LinkedBlockingQueue<>(),
+                daemonFactory("Iris Vision Render", Thread.NORM_PRIORITY, threadSequence)
+        );
+        this.renderExecutor.allowCoreThreadTimeOut(true);
+        this.probeExecutor = new ThreadPoolExecutor(
+                1,
+                1,
+                0L,
+                TimeUnit.MILLISECONDS,
+                new ArrayBlockingQueue<>(PROBE_QUEUE_CAPACITY),
+                daemonFactory("Iris Vision Probe", Thread.MIN_PRIORITY, threadSequence),
+                new ThreadPoolExecutor.DiscardOldestPolicy()
+        );
+        this.cache = new WeightedTileCache(CACHE_BYTES);
+        GuiHost.interruptOnPluginShutdown(renderExecutor);
+        GuiHost.interruptOnPluginShutdown(probeExecutor);
+    }
+
+    // Snapping to powers of two keeps every zoom within a level on the same tiles; nearest keeps tiles within 1.41x of screen size.
+    static double renderBlocksPerPixel(double viewBlocksPerPixel) {
+        double level = Math.pow(2D, Math.round(Math.log(viewBlocksPerPixel) / Math.log(2D)));
+        return Math.max(MINIMUM_RENDER_BLOCKS_PER_PIXEL, Math.min(MAXIMUM_BLOCKS_PER_PIXEL, level));
+    }
+
+    Frame request(RenderSpec spec) {
+        Objects.requireNonNull(spec, "spec");
+        if (closed.get()) {
+            throw new IllegalStateException("Vision render controller is closed");
+        }
+        double renderScale = renderBlocksPerPixel(spec.blocksPerPixel());
+        List<VisibleTile> tiles = visibleTiles(spec, renderScale);
+        Frame frame = new Frame(viewSequence.incrementAndGet(), spec, renderScale, tiles);
+        for (VisibleTile tile : tiles) {
+            tile.setTile(cachedTileServing(tile.key()));
+        }
+        currentFrame = frame;
+        probeSequence.incrementAndGet();
+        probeExecutor.getQueue().clear();
+        startWorkers();
+        publish();
+        return frame;
+    }
+
+    /**
+     * A tile from another zoom level covering the given one, to draw while the real tile renders.
+     */
+    Fallback fallback(Frame frame, VisibleTile tile) {
+        MapTile withoutHeights = cache.get(tile.key().withHeights(false));
+        if (withoutHeights != null) {
+            return new Fallback(List.of(new FallbackPiece(withoutHeights, 0, 0, TILE_PIXELS, 0D, 0D, 1D)));
+        }
+        Fallback coarser = coarserFallback(frame, tile);
+        return coarser != null ? coarser : finerFallback(frame, tile);
+    }
+
+    // A tile drawn with heights serves just as well where no heights are needed, so turning shading off redraws nothing.
+    private MapTile cachedTileServing(TileKey key) {
+        MapTile exact = cache.get(key);
+        if (exact != null || key.heights()) {
+            return exact;
+        }
+        return cache.get(key.withHeights(true));
+    }
+
+    Progress progress(Frame frame) {
+        if (frame == null) {
+            return new Progress(0, 0, 0);
+        }
+        int ready = 0;
+        for (VisibleTile tile : frame.tiles()) {
+            if (tile.tile() != null) {
+                ready++;
+            }
+        }
+        return new Progress(frame.tiles().size(), ready, activeWorkers.get());
+    }
+
+    <T> void submitProbe(Frame frame, Callable<T> probe, Consumer<T> consumer) {
+        Objects.requireNonNull(probe, "probe");
+        Objects.requireNonNull(consumer, "consumer");
+        if (frame == null || closed.get() || currentFrame != frame) {
+            return;
+        }
+        long probeRevision = probeSequence.incrementAndGet();
+        probeExecutor.getQueue().clear();
+        try {
+            probeExecutor.execute(() -> runProbe(probeRevision, probe, consumer));
+        } catch (RejectedExecutionException ignored) {
+            probeExecutor.getQueue().clear();
+        }
+    }
+
+    @Override
+    public void close() {
+        if (!closed.compareAndSet(false, true)) {
+            return;
+        }
+        currentFrame = null;
+        renderExecutor.shutdownNow();
+        probeExecutor.shutdownNow();
+        cache.clear();
+    }
+
+    static List<VisibleTile> visibleTiles(RenderSpec spec, double renderScale) {
+        Objects.requireNonNull(spec, "spec");
+        double blocksPerPixel = spec.blocksPerPixel();
+        double tileSpan = TILE_PIXELS * renderScale;
+        double halfWidth = spec.width() * blocksPerPixel * 0.5D;
+        double halfHeight = spec.height() * blocksPerPixel * 0.5D;
+        long minimumX = floorTile(spec.centerX() - halfWidth, tileSpan);
+        long maximumX = floorTile(Math.nextDown(spec.centerX() + halfWidth), tileSpan);
+        long minimumZ = floorTile(spec.centerZ() - halfHeight, tileSpan);
+        long maximumZ = floorTile(Math.nextDown(spec.centerZ() + halfHeight), tileSpan);
+        long tileCount = Math.multiplyExact(maximumX - minimumX + 1L, maximumZ - minimumZ + 1L);
+        if (tileCount > MAXIMUM_VISIBLE_TILES) {
+            throw new IllegalArgumentException("Vision viewport contains too many tiles");
+        }
+
+        ArrayList<VisibleTile> tiles = new ArrayList<>((int) tileCount);
+        double centerTileX = spec.centerX() / tileSpan;
+        double centerTileZ = spec.centerZ() / tileSpan;
+        for (long tileZ = minimumZ; tileZ <= maximumZ; tileZ++) {
+            for (long tileX = minimumX; tileX <= maximumX; tileX++) {
+                double deltaX = tileX + 0.5D - centerTileX;
+                double deltaZ = tileZ + 0.5D - centerTileZ;
+                TileKey key = new TileKey(spec.contentRevision(), spec.layer(), spec.heights(), renderScale, tileX, tileZ);
+                tiles.add(new VisibleTile(key, deltaX * deltaX + deltaZ * deltaZ));
+            }
+        }
+        tiles.sort(Comparator.comparingDouble(VisibleTile::distanceSquared)
+                .thenComparingLong(VisibleTile::tileZ)
+                .thenComparingLong(VisibleTile::tileX));
+        return List.copyOf(tiles);
+    }
+
+    private static long floorTile(double coordinate, double tileSpan) {
+        double tile = Math.floor(coordinate / tileSpan);
+        if (tile < Long.MIN_VALUE || tile > Long.MAX_VALUE) {
+            throw new IllegalArgumentException("Vision viewport exceeds tile coordinate range");
+        }
+        return (long) tile;
+    }
+
+    private static ThreadFactory daemonFactory(String name, int priority, AtomicInteger sequence) {
+        return (Runnable runnable) -> {
+            Thread thread = new Thread(runnable, name + " " + sequence.incrementAndGet());
+            thread.setDaemon(true);
+            thread.setPriority(priority);
+            thread.setUncaughtExceptionHandler((Thread failedThread, Throwable error) -> Iris.reportError(error));
+            return thread;
+        };
+    }
+
+    private void startWorkers() {
+        while (!closed.get()) {
+            int active = activeWorkers.get();
+            if (active >= workerCount || !hasWork()) {
+                return;
+            }
+            if (!activeWorkers.compareAndSet(active, active + 1)) {
+                continue;
+            }
+            try {
+                renderExecutor.execute(this::renderUntilIdle);
+            } catch (RejectedExecutionException ignored) {
+                activeWorkers.decrementAndGet();
+                return;
+            }
+        }
+    }
+
+    // Each worker keeps taking the most central missing tile of whatever frame is current, until the screen is covered.
+    private void renderUntilIdle() {
+        try {
+            TileJob job;
+            while ((job = claimNextTile()) != null) {
+                render(job);
+            }
+        } finally {
+            activeWorkers.decrementAndGet();
+        }
+        startWorkers();
+    }
+
+    private synchronized boolean hasWork() {
+        Frame frame = currentFrame;
+        return frame != null && frame.nextMissing(tilesInFlight, false) != null;
+    }
+
+    private synchronized TileJob claimNextTile() {
+        Frame frame = currentFrame;
+        if (frame == null || closed.get()) {
+            return null;
+        }
+        VisibleTile tile = frame.nextMissing(tilesInFlight, true);
+        if (tile == null) {
+            return null;
+        }
+        tilesInFlight.add(tile.key());
+        return new TileJob(frame.spec().renderer(), tile.key());
+    }
+
+    private synchronized void release(TileKey key) {
+        tilesInFlight.remove(key);
+    }
+
+    private void render(TileJob job) {
+        TileKey key = job.key();
+        try {
+            double tileSpan = TILE_PIXELS * key.blocksPerPixel();
+            MapTile tile = job.renderer().renderTile(
+                    key.tileX() * tileSpan,
+                    key.tileZ() * tileSpan,
+                    key.blocksPerPixel(),
+                    TILE_PIXELS,
+                    key.layer(),
+                    key.heights(),
+                    () -> !isWanted(key)
+            );
+            cache.put(key, tile);
+            Frame frame = currentFrame;
+            VisibleTile visible = frame == null ? null : frame.tile(key);
+            if (visible != null) {
+                visible.setTile(tile);
+                publish();
+            }
+        } catch (CancellationException ignored) {
+        } catch (Throwable error) {
+            Iris.debug("Vision tile render failed: " + error.getClass().getSimpleName() + ": " + error.getMessage());
+        } finally {
+            release(key);
+        }
+    }
+
+    private boolean isWanted(TileKey key) {
+        Frame frame = currentFrame;
+        return !closed.get() && frame != null && frame.tile(key) != null;
+    }
+
+    private Fallback coarserFallback(Frame frame, VisibleTile tile) {
+        TileKey key = tile.key();
+        for (int level = 1; level <= COARSER_FALLBACK_LEVELS; level++) {
+            long scale = 1L << level;
+            int sourceSize = TILE_PIXELS >> level;
+            double parentScale = key.blocksPerPixel() * scale;
+            if (sourceSize < 1 || parentScale > MAXIMUM_BLOCKS_PER_PIXEL) {
+                return null;
+            }
+            long parentX = Math.floorDiv(key.tileX(), scale);
+            long parentZ = Math.floorDiv(key.tileZ(), scale);
+            MapTile parent = cache.get(new TileKey(key.contentRevision(), key.layer(), key.heights(), parentScale, parentX,
+                    parentZ));
+            if (parent != null) {
+                int sourceX = (int) (key.tileX() - parentX * scale) * sourceSize;
+                int sourceZ = (int) (key.tileZ() - parentZ * scale) * sourceSize;
+                return new Fallback(List.of(new FallbackPiece(parent, sourceX, sourceZ, sourceSize, 0D, 0D, 1D)));
+            }
+        }
+        return null;
+    }
+
+    private Fallback finerFallback(Frame frame, VisibleTile tile) {
+        TileKey key = tile.key();
+        double childScale = key.blocksPerPixel() / 2D;
+        if (childScale < MINIMUM_RENDER_BLOCKS_PER_PIXEL) {
+            return null;
+        }
+        List<FallbackPiece> pieces = new ArrayList<>(4);
+        for (int childZ = 0; childZ < 2; childZ++) {
+            for (int childX = 0; childX < 2; childX++) {
+                MapTile child = cache.get(new TileKey(key.contentRevision(), key.layer(), key.heights(), childScale,
+                        key.tileX() * 2L + childX, key.tileZ() * 2L + childZ));
+                if (child != null) {
+                    pieces.add(new FallbackPiece(child, 0, 0, TILE_PIXELS, childX * 0.5D, childZ * 0.5D, 0.5D));
+                }
+            }
+        }
+        return pieces.isEmpty() ? null : new Fallback(List.copyOf(pieces));
+    }
+
+    private <T> void runProbe(long probeRevision, Callable<T> probe, Consumer<T> consumer) {
+        try {
+            if (!isProbeCurrent(probeRevision)) {
+                return;
+            }
+            T result = probe.call();
+            if (!isProbeCurrent(probeRevision)) {
+                return;
+            }
+            EventQueue.invokeLater(() -> {
+                if (isProbeCurrent(probeRevision)) {
+                    consumer.accept(result);
+                }
+            });
+        } catch (InterruptedException interrupted) {
+            Thread.currentThread().interrupt();
+        } catch (Throwable error) {
+            Iris.debug("Vision probe failed: " + error.getClass().getSimpleName() + ": " + error.getMessage());
+        }
+    }
+
+    private boolean isProbeCurrent(long probeRevision) {
+        return !closed.get() && probeSequence.get() == probeRevision;
+    }
+
+    private void publish() {
+        if (closed.get()) {
+            return;
+        }
+        publicationDirty.set(true);
+        queuePublication();
+    }
+
+    private void queuePublication() {
+        if (!publicationQueued.compareAndSet(false, true)) {
+            return;
+        }
+        EventQueue.invokeLater(() -> {
+            try {
+                if (publicationDirty.getAndSet(false) && !closed.get()) {
+                    listener.run();
+                }
+            } finally {
+                publicationQueued.set(false);
+                if (publicationDirty.get() && !closed.get()) {
+                    queuePublication();
+                }
+            }
+        });
+    }
+
+    record RenderSpec(
+            IrisRenderer renderer,
+            MapLayer layer,
+            long contentRevision,
+            double centerX,
+            double centerZ,
+            double blocksPerPixel,
+            int width,
+            int height,
+            boolean heights
+    ) {
+        RenderSpec {
+            Objects.requireNonNull(renderer, "renderer");
+            Objects.requireNonNull(layer, "layer");
+            if (!Double.isFinite(centerX) || !Double.isFinite(centerZ)) {
+                throw new IllegalArgumentException("Vision center must be finite");
+            }
+            if (!Double.isFinite(blocksPerPixel)
+                    || blocksPerPixel < MINIMUM_VIEW_BLOCKS_PER_PIXEL
+                    || blocksPerPixel > MAXIMUM_BLOCKS_PER_PIXEL) {
+                throw new IllegalArgumentException("Vision scale is outside the supported range");
+            }
+            if (width < 1 || height < 1) {
+                throw new IllegalArgumentException("Vision viewport must be positive");
+            }
+        }
+    }
+
+    static final class Frame {
+        private final long viewRevision;
+        private final RenderSpec spec;
+        private final double renderBlocksPerPixel;
+        private final List<VisibleTile> tiles;
+        private final Map<TileKey, VisibleTile> tilesByKey;
+        private int nextCandidate;
+
+        private Frame(long viewRevision, RenderSpec spec, double renderBlocksPerPixel, List<VisibleTile> tiles) {
+            this.viewRevision = viewRevision;
+            this.spec = Objects.requireNonNull(spec, "spec");
+            this.renderBlocksPerPixel = renderBlocksPerPixel;
+            this.tiles = tiles;
+            this.tilesByKey = new HashMap<>(tiles.size() * 2);
+            for (VisibleTile tile : tiles) {
+                tilesByKey.put(tile.key(), tile);
+            }
+        }
+
+        long viewRevision() {
+            return viewRevision;
+        }
+
+        RenderSpec spec() {
+            return spec;
+        }
+
+        double renderBlocksPerPixel() {
+            return renderBlocksPerPixel;
+        }
+
+        List<VisibleTile> tiles() {
+            return tiles;
+        }
+
+        private VisibleTile tile(TileKey key) {
+            return tilesByKey.get(key);
+        }
+
+        /**
+         * The tile covering a world position together with the pixel of it there, or null when that tile is not drawn yet.
+         */
+        TilePixel pixelAt(double worldX, double worldZ) {
+            double tileSpan = TILE_PIXELS * renderBlocksPerPixel;
+            long tileX = (long) Math.floor(worldX / tileSpan);
+            long tileZ = (long) Math.floor(worldZ / tileSpan);
+            VisibleTile visible = tilesByKey.get(new TileKey(spec.contentRevision(), spec.layer(), spec.heights(),
+                    renderBlocksPerPixel, tileX, tileZ));
+            MapTile tile = visible == null ? null : visible.tile();
+            if (tile == null) {
+                return null;
+            }
+            int pixelX = pixelWithin(worldX - tileX * tileSpan);
+            int pixelZ = pixelWithin(worldZ - tileZ * tileSpan);
+            return new TilePixel(tile, pixelX, pixelZ);
+        }
+
+        private int pixelWithin(double offsetBlocks) {
+            return Math.max(0, Math.min(TILE_PIXELS - 1, (int) Math.floor(offsetBlocks / renderBlocksPerPixel)));
+        }
+
+        // Tiles are sorted centre first, and everything before the cursor is drawn or claimed, so each search resumes there.
+        private VisibleTile nextMissing(Set<TileKey> inFlight, boolean advance) {
+            for (int index = nextCandidate; index < tiles.size(); index++) {
+                VisibleTile tile = tiles.get(index);
+                if (tile.tile() == null && !inFlight.contains(tile.key())) {
+                    if (advance) {
+                        nextCandidate = index + 1;
+                    }
+                    return tile;
+                }
+            }
+            if (advance) {
+                nextCandidate = tiles.size();
+            }
+            return null;
+        }
+    }
+
+    static final class VisibleTile {
+        private final TileKey key;
+        private final double distanceSquared;
+        private volatile MapTile tile;
+
+        private VisibleTile(TileKey key, double distanceSquared) {
+            this.key = key;
+            this.distanceSquared = distanceSquared;
+        }
+
+        TileKey key() {
+            return key;
+        }
+
+        long tileX() {
+            return key.tileX();
+        }
+
+        long tileZ() {
+            return key.tileZ();
+        }
+
+        double distanceSquared() {
+            return distanceSquared;
+        }
+
+        MapTile tile() {
+            return tile;
+        }
+
+        private void setTile(MapTile tile) {
+            this.tile = tile;
+        }
+    }
+
+    /**
+     * @param heights whether the tile also carries terrain heights, for shading
+     */
+    record TileKey(long contentRevision, MapLayer layer, boolean heights, double blocksPerPixel, long tileX, long tileZ) {
+        TileKey {
+            Objects.requireNonNull(layer, "layer");
+            if (!Double.isFinite(blocksPerPixel) || blocksPerPixel <= 0D) {
+                throw new IllegalArgumentException("Vision cache scale must be finite and positive");
+            }
+        }
+
+        TileKey withHeights(boolean nextHeights) {
+            return new TileKey(contentRevision, layer, nextHeights, blocksPerPixel, tileX, tileZ);
+        }
+    }
+
+    record TilePixel(MapTile tile, int pixelX, int pixelZ) {
+        MapLabels.Label subject() {
+            return tile.labels().label(tile.subjectAt(pixelX, pixelZ));
+        }
+
+        MapLabels.Label region() {
+            return tile.labels().label(tile.regionAt(pixelX, pixelZ));
+        }
+    }
+
+    /**
+     * Pieces of cached tiles that together cover a missing tile; offsets and size are fractions of the tile.
+     */
+    record Fallback(List<FallbackPiece> pieces) {
+    }
+
+    record FallbackPiece(MapTile tile, int sourceX, int sourceZ, int sourceSize, double offsetX, double offsetZ,
+                         double size) {
+    }
+
+    record Progress(int total, int ready, int activeWorkers) {
+        double completion() {
+            if (total == 0) {
+                return 1D;
+            }
+            return Math.min(1D, ready / (double) total);
+        }
+    }
+
+    private record TileJob(IrisRenderer renderer, TileKey key) {
+    }
+
+    private static final class WeightedTileCache {
+        private final long maximumBytes;
+        private final LinkedHashMap<TileKey, CacheEntry> entries;
+        private long bytes;
+
+        private WeightedTileCache(long maximumBytes) {
+            this.maximumBytes = maximumBytes;
+            this.entries = new LinkedHashMap<>(128, 0.75F, true);
+        }
+
+        synchronized MapTile get(TileKey key) {
+            CacheEntry entry = entries.get(key);
+            return entry == null ? null : entry.tile();
+        }
+
+        synchronized void put(TileKey key, MapTile tile) {
+            long tileBytes = tile.bytes();
+            CacheEntry previous = entries.put(key, new CacheEntry(tile, tileBytes));
+            if (previous != null) {
+                bytes -= previous.bytes();
+            }
+            bytes += tileBytes;
+            while (bytes > maximumBytes && !entries.isEmpty()) {
+                Iterator<Map.Entry<TileKey, CacheEntry>> iterator = entries.entrySet().iterator();
+                Map.Entry<TileKey, CacheEntry> eldest = iterator.next();
+                bytes -= eldest.getValue().bytes();
+                iterator.remove();
+            }
+        }
+
+        synchronized void clear() {
+            entries.clear();
+            bytes = 0L;
+        }
+    }
+
+    private record CacheEntry(MapTile tile, long bytes) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/VisionViewport.java

@@ -0,0 +1,60 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+record VisionViewport(double centerX, double centerZ, double blocksPerPixel) {
+    VisionViewport {
+        if (!Double.isFinite(centerX) || !Double.isFinite(centerZ)) {
+            throw new IllegalArgumentException("Vision viewport center must be finite");
+        }
+        if (!Double.isFinite(blocksPerPixel) || blocksPerPixel <= 0D) {
+            throw new IllegalArgumentException("Vision viewport scale must be finite and positive");
+        }
+    }
+
+    double worldX(double screenX, int width) {
+        return centerX + (screenX - width * 0.5D) * blocksPerPixel;
+    }
+
+    double worldZ(double screenZ, int height) {
+        return centerZ + (screenZ - height * 0.5D) * blocksPerPixel;
+    }
+
+    VisionViewport zoomAt(
+            double screenX,
+            double screenZ,
+            int width,
+            int height,
+            double factor,
+            double minimumScale,
+            double maximumScale
+    ) {
+        if (!Double.isFinite(factor) || factor <= 0D) {
+            throw new IllegalArgumentException("Vision zoom factor must be finite and positive");
+        }
+        double anchorX = worldX(screenX, width);
+        double anchorZ = worldZ(screenZ, height);
+        double nextScale = Math.max(minimumScale, Math.min(maximumScale, blocksPerPixel * factor));
+        return new VisionViewport(
+                anchorX - (screenX - width * 0.5D) * nextScale,
+                anchorZ - (screenZ - height * 0.5D) * nextScale,
+                nextScale
+        );
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/XwaylandWindowManagerHint.java

@@ -0,0 +1,86 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import com.sun.jna.platform.linux.LibC;
+import com.volmit.iris.Iris;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * Java does not recognise the non-reparenting Xwayland window managers of compositors such as niri, sway and Hyprland.
+ * It waits for a reparent that never comes and paints only a corner of each window. Java reads this hint from the
+ * native environment once, at the first decorated window, so it is set through libc before Iris opens any window.
+ */
+final class XwaylandWindowManagerHint {
+    private static final String NON_REPARENTING_VARIABLE = "_JAVA_AWT_WM_NONREPARENTING";
+    private static final int KEEP_EXISTING_VALUE = 0;
+    private static final List<String> REPARENTING_DESKTOPS = List.of("GNOME", "KDE");
+    private static final AtomicBoolean APPLIED = new AtomicBoolean();
+
+    private XwaylandWindowManagerHint() {
+    }
+
+    static void apply() {
+        if (!APPLIED.compareAndSet(false, true) || !isNeeded(System.getenv(), System.getProperty("os.name", ""))) {
+            return;
+        }
+
+        try {
+            if (LibC.INSTANCE.setenv(NON_REPARENTING_VARIABLE, "1", KEEP_EXISTING_VALUE) != 0) {
+                warnUnapplied();
+            }
+        } catch (Throwable e) {
+            Iris.reportError(e);
+            warnUnapplied();
+        }
+    }
+
+    static boolean isNeeded(Map<String, String> environment, String osName) {
+        return osName.toLowerCase(Locale.ROOT).contains("linux")
+                && isSet(environment, "WAYLAND_DISPLAY")
+                && isSet(environment, "DISPLAY")
+                && !isSet(environment, NON_REPARENTING_VARIABLE)
+                && !isReparentingDesktop(environment.get("XDG_CURRENT_DESKTOP"));
+    }
+
+    private static boolean isReparentingDesktop(String currentDesktop) {
+        if (currentDesktop == null) {
+            return false;
+        }
+
+        return Arrays.stream(currentDesktop.split(":"))
+                .map(desktop -> desktop.trim().toUpperCase(Locale.ROOT))
+                .anyMatch(REPARENTING_DESKTOPS::contains);
+    }
+
+    private static boolean isSet(Map<String, String> environment, String variable) {
+        String value = environment.get(variable);
+        return value != null && !value.isBlank();
+    }
+
+    private static void warnUnapplied() {
+        Iris.warn("Iris could not adjust Java for this Wayland desktop, so its windows may stay blank. "
+                + "Start the server with %s=1 set to fix that.", NON_REPARENTING_VARIABLE);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/components/IrisRenderer.java

@@ -18,68 +18,613 @@
 
 package com.volmit.iris.core.gui.components;
 
+import com.volmit.iris.engine.IrisComplex;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.InferredType;
 import com.volmit.iris.engine.object.IrisBiome;
 import com.volmit.iris.engine.object.IrisBiomeGeneratorLink;
-import com.volmit.iris.util.interpolation.IrisInterpolation;
+import com.volmit.iris.engine.object.IrisDimension;
+import com.volmit.iris.engine.object.IrisRegion;
+import com.volmit.iris.util.stream.ProceduralStream;
 
-import java.awt.*;
-import java.awt.image.BufferedImage;
-import java.util.function.BiFunction;
+import java.awt.Color;
+import java.util.Arrays;
+import java.util.EnumMap;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.BooleanSupplier;
 
-public class IrisRenderer {
-    private final Engine renderer;
+/**
+ * Draws map tiles for one generation of the pack: a hotload needs a new renderer, which also starts new labels.
+ */
+public final class IrisRenderer {
+    private static final int BLUE = rgb(45, 91, 156);
+    private static final int YELLOW = rgb(211, 164, 67);
+    private static final int GREEN = rgb(78, 137, 83);
+    private static final int DEEP_WATER = rgb(20, 48, 92);
+    private static final int SHALLOW_WATER = rgb(50, 112, 154);
+    private static final int LOWLAND = rgb(78, 128, 76);
+    private static final int HIGHLAND = rgb(151, 139, 92);
+    private static final int ROCK = rgb(126, 119, 112);
+    private static final int SNOW = rgb(226, 230, 232);
+    private static final int UNKNOWN_SUBJECT = rgb(90, 92, 98);
+    private static final int LARGEST_SAMPLE_BLOCK_PIXELS = 16;
+    private static final double LARGEST_SAMPLE_BLOCK_BLOCKS = 64D;
+    private static final double DEFAULT_DEPTH_BELOW_SEA_BLOCKS = 48D;
+    private static final double DEFAULT_HEIGHT_ABOVE_SEA_BLOCKS = 160D;
+    private static final int NOISE_LOW = rgb(5, 5, 5);
+    private static final int NOISE_HIGH = rgb(255, 255, 255);
+    private static final double DARKEST_PICK_SHADE = 0.3D;
 
-    public IrisRenderer(Engine renderer) {
-        this.renderer = renderer;
+    private final Engine engine;
+    private final MapLabels labels = new MapLabels();
+    private final ConcurrentHashMap<LabelColorKey, Integer> labelColors = new ConcurrentHashMap<>();
+
+    public IrisRenderer(Engine engine) {
+        this.engine = Objects.requireNonNull(engine, "engine");
     }
 
-    public BufferedImage render(double sx, double sz, double size, int resolution, RenderType currentType) {
-        BufferedImage image = new BufferedImage(resolution, resolution, BufferedImage.TYPE_INT_RGB);
-        BiFunction<Double, Double, Integer> colorFunction = (d, dx) -> Color.black.getRGB();
+    public MapLabels labels() {
+        return labels;
+    }
 
-        switch (currentType) {
-            case BIOME, DECORATOR_LOAD, OBJECT_LOAD, LAYER_LOAD ->
-                    colorFunction = (x, z) -> renderer.getComplex().getTrueBiomeStream().get(x, z).getColor(renderer, currentType).getRGB();
-            case BIOME_LAND ->
-                    colorFunction = (x, z) -> renderer.getComplex().getLandBiomeStream().get(x, z).getColor(renderer, currentType).getRGB();
-            case BIOME_SEA ->
-                    colorFunction = (x, z) -> renderer.getComplex().getSeaBiomeStream().get(x, z).getColor(renderer, currentType).getRGB();
-            case REGION ->
-                    colorFunction = (x, z) -> renderer.getComplex().getRegionStream().get(x, z).getColor(renderer.getComplex(), currentType).getRGB();
-            case CAVE_LAND ->
-                    colorFunction = (x, z) -> renderer.getComplex().getCaveBiomeStream().get(x, z).getColor(renderer, currentType).getRGB();
-            case HEIGHT ->
-                    colorFunction = (x, z) -> Color.getHSBColor(renderer.getComplex().getHeightStream().get(x, z).floatValue(), 100, 100).getRGB();
-            case CONTINENT -> colorFunction = (x, z) -> {
-                IrisBiome b = renderer.getBiome((int) Math.round(x), renderer.getMaxHeight() - 1, (int) Math.round(z));
-                IrisBiomeGeneratorLink g = b.getGenerators().get(0);
-                Color c;
-                if (g.getMax() <= 0) {
-                    // Max is below water level, so it is most likely an ocean biome
-                    c = Color.BLUE;
-                } else if (g.getMin() < 0) {
-                    // Min is below water level, but max is not, so it is most likely a shore biome
-                    c = Color.YELLOW;
-                } else {
-                    // Both min and max are above water level, so it is most likely a land biome
-                    c = Color.GREEN;
-                }
-                return c.getRGB();
-            };
+    /**
+     * Renders the square of {@code size} pixels whose top left pixel samples the given world position.
+     *
+     * @param withHeights also sample terrain heights for shading; the height view always has them
+     */
+    public MapTile renderTile(
+            double startX,
+            double startZ,
+            double blocksPerPixel,
+            int size,
+            MapLayer layer,
+            boolean withHeights,
+            BooleanSupplier cancelled
+    ) {
+        if (!Double.isFinite(startX) || !Double.isFinite(startZ) || !Double.isFinite(blocksPerPixel) || blocksPerPixel <= 0D) {
+            throw new IllegalArgumentException("Map tile coordinates and scale must be finite");
+        }
+        if (size < 1) {
+            throw new IllegalArgumentException("Map tile size must be positive");
+        }
+        Objects.requireNonNull(layer, "layer");
+        Objects.requireNonNull(cancelled, "cancelled");
+        RenderType type = layer.type();
+        checkCancelled(cancelled);
+
+        TileGrid grid = new TileGrid(size + 2, startX - blocksPerPixel, startZ - blocksPerPixel, blocksPerPixel, cancelled);
+        int[] identities = sampleIdentities(grid, layer);
+        double[] heights = withHeights || type == RenderType.HEIGHT ? sampleHeights(grid) : null;
+        short[] subjects = new short[identities.length];
+        short[] regions = new short[identities.length];
+        for (int index = 0; index < identities.length; index++) {
+            subjects[index] = subjectOf(identities[index]);
+            regions[index] = regionOf(identities[index]);
+        }
+        int[] colors = type == RenderType.HEIGHT ? null : tileColors(size, type, subjects);
+        if (layer.display() != PickDisplay.PICKS) {
+            drawPickNoise(colors, grid, size, layer);
+        }
+        MapLabels.Kind subjectKind = type == RenderType.REGION ? MapLabels.Kind.REGION : MapLabels.Kind.BIOME;
+        return new MapTile(size, blocksPerPixel, labels, subjectKind, colors, defaultHeightRange(), subjects, regions, heights);
+    }
+
+    /**
+     * The colour a biome or region has on the map in the given view, for legends.
+     */
+    public int legendColor(MapLabels.Label label, RenderType type) {
+        RenderType colorType = type == RenderType.HEIGHT ? RenderType.BIOME : type;
+        return labelColor(label.id(), colorType);
+    }
+
+    /**
+     * Until the map has measured the heights on screen, land colours cover the band most terrain sits in.
+     */
+    public MapStyle.HeightRange defaultHeightRange() {
+        double seaLevel = fluidHeight();
+        return new MapStyle.HeightRange(Math.max(0D, seaLevel - DEFAULT_DEPTH_BELOW_SEA_BLOCKS), seaLevel,
+                Math.min(engine.getHeight(), seaLevel + DEFAULT_HEIGHT_ABOVE_SEA_BLOCKS));
+    }
+
+    public static int heightColor(double height, MapStyle.HeightRange range) {
+        double seaLevel = range.seaLevel();
+        if (height <= seaLevel) {
+            double waterDepthRange = Math.max(1D, seaLevel - range.lowest());
+            return blend(DEEP_WATER, SHALLOW_WATER, (height - range.lowest()) / waterDepthRange);
         }
 
-        double x, z;
-        int i, j;
-        for (i = 0; i < resolution; i++) {
-            x = IrisInterpolation.lerp(sx, sx + size, (double) i / (double) (resolution));
+        double landRange = Math.max(1D, range.highest() - seaLevel);
+        double land = clamp((height - seaLevel) / landRange, 0D, 1D);
+        if (land < 0.45D) {
+            return blend(LOWLAND, HIGHLAND, land / 0.45D);
+        }
+        if (land < 0.78D) {
+            return blend(HIGHLAND, ROCK, (land - 0.45D) / 0.33D);
+        }
+        return blend(ROCK, SNOW, (land - 0.78D) / 0.22D);
+    }
 
-            for (j = 0; j < resolution; j++) {
-                z = IrisInterpolation.lerp(sz, sz + size, (double) j / (double) (resolution));
-                image.setRGB(i, j, colorFunction.apply(x, z));
+    private int[] sampleIdentities(TileGrid grid, MapLayer layer) {
+        IdentitySampler sampler = new IdentitySampler(grid, identityShader(layer));
+        sampler.renderAll(sampleBlockPixels(grid.step()));
+        return sampler.identities;
+    }
+
+    private double[] sampleHeights(TileGrid grid) {
+        return new HeightLattice(grid, engine.getComplex().getHeightStream()).interpolatedHeights();
+    }
+
+    // Large uniform squares are filled after a few samples; squares stay small enough to not skip tiny biomes.
+    private static int sampleBlockPixels(double blocksPerPixel) {
+        int largestPixels = (int) Math.floor(LARGEST_SAMPLE_BLOCK_BLOCKS / blocksPerPixel);
+        return Integer.highestOneBit(Math.max(1, Math.min(LARGEST_SAMPLE_BLOCK_PIXELS, largestPixels)));
+    }
+
+    private IdentityShader identityShader(MapLayer layer) {
+        IrisComplex complex = engine.getComplex();
+        ProceduralStream<IrisRegion> regionStream = complex.getRegionStream();
+        LabelLookup lookup = new LabelLookup(labels);
+        if (layer.type() == RenderType.REGION) {
+            return (double x, double z) -> {
+                short region = lookup.idOf(regionStream.get(x, z));
+                return identity(region, region);
+            };
+        }
+        if (layer.type() == RenderType.REGION_PREVIEW) {
+            return regionPreviewShader(complex, layer.previewRegionKey(), lookup);
+        }
+        ProceduralStream<IrisBiome> biomeStream = subjectBiomeStream(complex, layer.type());
+        return (double x, double z) -> identity(lookup.idOf(biomeStream.get(x, z)), lookup.idOf(regionStream.get(x, z)));
+    }
+
+    // Every spot is treated as part of the previewed region, so the tile shows the biomes that region places there.
+    private IdentityShader regionPreviewShader(IrisComplex complex, String regionKey, LabelLookup lookup) {
+        IrisRegion region = engine.getData().getRegionLoader().load(regionKey);
+        if (region == null) {
+            return (double x, double z) -> identity(MapLabels.NONE, MapLabels.NONE);
+        }
+        short regionId = lookup.idOf(region);
+        return (double x, double z) -> identity(lookup.idOf(complex.surfaceBiomeAsIfIn(region, x, z)), regionId);
+    }
+
+    private void drawPickNoise(int[] colors, TileGrid grid, int size, MapLayer layer) {
+        PickNoise noise = pickNoise(grid, layer);
+        for (int pixelZ = 0; pixelZ < size; pixelZ++) {
+            checkCancelled(grid.cancelled());
+            double worldZ = grid.worldZ(pixelZ + 1);
+            for (int pixelX = 0; pixelX < size; pixelX++) {
+                int index = pixelZ * size + pixelX;
+                double value = noise.valueAt((pixelZ + 1) * grid.size() + pixelX + 1, grid.worldX(pixelX + 1), worldZ);
+                colors[index] = layer.display() == PickDisplay.NOISE
+                        ? noise.color(value)
+                        : shade(colors[index], DARKEST_PICK_SHADE + (1D - DARKEST_PICK_SHADE) * noise.brightness(value));
+            }
+        }
+    }
+
+    // Regions and BIOME terrain biomes are picked by splitting a noise by rarity; HYBRID terrain biomes by a height.
+    private PickNoise pickNoise(TileGrid grid, MapLayer layer) {
+        IrisComplex complex = engine.getComplex();
+        if (layer.type() == RenderType.REGION) {
+            ProceduralStream<Double> regionNoise = complex.getRegionStyleStream();
+            return new UnitNoise((gridIndex, x, z) -> regionNoise.get(x, z));
+        }
+        if (complex.isHybridTerrain()) {
+            ProceduralStream<Double> placementHeight = complex.getPlacementHeightStream();
+            return new PlacementHeightNoise((gridIndex, x, z) -> placementHeight.get(x, z), fluidHeight(), defaultHeightRange());
+        }
+        if (layer.type() == RenderType.BIOME) {
+            return new UnitNoise(baseBiomePickNoise(complex));
+        }
+        IrisRegion region = engine.getData().getRegionLoader().load(layer.previewRegionKey());
+        if (region == null) {
+            return new UnitNoise((gridIndex, x, z) -> 0D);
+        }
+        return new UnitNoise(biomePickNoise(complex, region, grid));
+    }
+
+    // The biome view shows each spot's base biome, which its own region picks from the biome list of the spot's type.
+    private static NoiseField baseBiomePickNoise(IrisComplex complex) {
+        ProceduralStream<IrisRegion> regions = complex.getRegionStream();
+        ProceduralStream<InferredType> types = complex.getBridgeStream();
+        Map<IrisRegion, Map<InferredType, ProceduralStream<Double>>> noiseByRegion = new IdentityHashMap<>();
+        return (gridIndex, x, z) -> {
+            IrisRegion region = regions.get(x, z);
+            return noiseByRegion.computeIfAbsent(region, subject -> new EnumMap<>(InferredType.class))
+                    .computeIfAbsent(types.get(x, z), type -> complex.biomePickNoiseStream(region, type))
+                    .get(x, z);
+        };
+    }
+
+    // Finding which biome list picked a spot is slow, so it is sampled in squares like the biomes; the noise is cheap.
+    private static NoiseField biomePickNoise(IrisComplex complex, IrisRegion region, TileGrid grid) {
+        IdentitySampler typeSampler = new IdentitySampler(grid, (x, z) -> complex.surfacePickAsIfIn(region, x, z).type().ordinal());
+        typeSampler.renderAll(sampleBlockPixels(grid.step()));
+        int[] typeByGridIndex = typeSampler.identities;
+        InferredType[] types = InferredType.values();
+        Map<InferredType, ProceduralStream<Double>> noiseByType = new EnumMap<>(InferredType.class);
+        return (gridIndex, x, z) -> noiseByType
+                .computeIfAbsent(types[typeByGridIndex[gridIndex]], type -> complex.biomePickNoiseStream(region, type))
+                .get(x, z);
+    }
+
+    // Hybrid terrain decides land, coast and sea by height after the biomes are chosen, so the final biome tells.
+    private static ProceduralStream<IrisBiome> subjectBiomeStream(IrisComplex complex, RenderType type) {
+        return switch (type) {
+            case BIOME_LAND -> complex.getLandBiomeStream();
+            case BIOME_SEA -> complex.getSeaBiomeStream();
+            case CAVE_LAND -> complex.getCaveBiomeStream();
+            case CONTINENT -> complex.isHybridTerrain() ? complex.getTrueBiomeStream() : complex.getBaseBiomeStream();
+            case BIOME, HEIGHT, REGION, REGION_PREVIEW -> complex.getBaseBiomeStream();
+        };
+    }
+
+    private int[] tileColors(int size, RenderType type, short[] subjects) {
+        int[] colors = new int[size * size];
+        short previousSubject = MapLabels.NONE;
+        int previousColor = UNKNOWN_SUBJECT;
+        for (int pixelZ = 0; pixelZ < size; pixelZ++) {
+            for (int pixelX = 0; pixelX < size; pixelX++) {
+                int gridIndex = (pixelZ + 1) * (size + 2) + pixelX + 1;
+                short subject = subjects[gridIndex];
+                if (subject != previousSubject) {
+                    previousSubject = subject;
+                    previousColor = labelColor(subject, type);
+                }
+                colors[pixelZ * size + pixelX] = previousColor;
+            }
+        }
+        return colors;
+    }
+
+    private double fluidHeight() {
+        IrisDimension dimension = engine.getDimension();
+        return dimension == null ? 0D : dimension.getFluidHeight();
+    }
+
+    private int labelColor(short id, RenderType type) {
+        MapLabels.Label label = labels.label(id);
+        if (label == null) {
+            return UNKNOWN_SUBJECT;
+        }
+        return labelColors.computeIfAbsent(new LabelColorKey(type, id), key -> subjectColor(label.subject(), type));
+    }
+
+    private int subjectColor(Object subject, RenderType type) {
+        if (type == RenderType.CONTINENT && subject instanceof IrisBiome biome) {
+            return engine.getComplex().isHybridTerrain() ? continentColorByPlacement(biome) : continentColor(biome);
+        }
+        if (subject instanceof IrisRegion region) {
+            return region.getColor(engine.getComplex(), type).getRGB() & 0xFFFFFF;
+        }
+        if (subject instanceof IrisBiome biome) {
+            return biome.getColor(engine, type).getRGB() & 0xFFFFFF;
+        }
+        return UNKNOWN_SUBJECT;
+    }
+
+    private static int continentColor(IrisBiome biome) {
+        List<IrisBiomeGeneratorLink> generators = biome.getGenerators();
+        if (generators.isEmpty()) {
+            return GREEN;
+        }
+        IrisBiomeGeneratorLink generator = generators.get(0);
+        if (generator.getMax() <= 0D) {
+            return BLUE;
+        }
+        if (generator.getMin() < 0D) {
+            return YELLOW;
+        }
+        return GREEN;
+    }
+
+    private static int continentColorByPlacement(IrisBiome biome) {
+        if (biome.isShore()) {
+            return YELLOW;
+        }
+        return biome.isSea() ? BLUE : GREEN;
+    }
+
+    private static int identity(short subject, short region) {
+        return (subject << 16) | (region & 0xFFFF);
+    }
+
+    private static short subjectOf(int identity) {
+        return (short) (identity >> 16);
+    }
+
+    private static short regionOf(int identity) {
+        return (short) identity;
+    }
+
+    private static int rgb(int red, int green, int blue) {
+        return new Color(red, green, blue).getRGB() & 0xFFFFFF;
+    }
+
+    private static int shade(int color, double brightness) {
+        int red = (int) Math.round(((color >> 16) & 0xFF) * brightness);
+        int green = (int) Math.round(((color >> 8) & 0xFF) * brightness);
+        int blue = (int) Math.round((color & 0xFF) * brightness);
+        return (red << 16) | (green << 8) | blue;
+    }
+
+    private static int blend(int first, int second, double progress) {
+        double bounded = clamp(progress, 0D, 1D);
+        int red = (int) Math.round(((first >> 16) & 0xFF) * (1D - bounded) + ((second >> 16) & 0xFF) * bounded);
+        int green = (int) Math.round(((first >> 8) & 0xFF) * (1D - bounded) + ((second >> 8) & 0xFF) * bounded);
+        int blue = (int) Math.round((first & 0xFF) * (1D - bounded) + (second & 0xFF) * bounded);
+        return (red << 16) | (green << 8) | blue;
+    }
+
+    private static double clamp(double value, double minimum, double maximum) {
+        return Math.max(minimum, Math.min(maximum, value));
+    }
+
+    private static void checkCancelled(BooleanSupplier cancelled) {
+        if (cancelled.getAsBoolean() || Thread.currentThread().isInterrupted()) {
+            throw new CancellationException("Map tile render cancelled");
+        }
+    }
+
+    @FunctionalInterface
+    private interface IdentityShader {
+        int identity(double x, double z);
+    }
+
+    private record LabelColorKey(RenderType type, short id) {
+    }
+
+    @FunctionalInterface
+    private interface NoiseField {
+        double at(int gridIndex, double x, double z);
+    }
+
+    /**
+     * A noise that picks regions or biomes, drawn on its own or as how bright the picks are.
+     */
+    private interface PickNoise {
+        double valueAt(int gridIndex, double x, double z);
+
+        int color(double value);
+
+        double brightness(double value);
+    }
+
+    /**
+     * A noise whose values run from 0 to 1, split into one band per region or biome by their rarities.
+     */
+    private record UnitNoise(NoiseField field) implements PickNoise {
+        @Override
+        public double valueAt(int gridIndex, double x, double z) {
+            return field.at(gridIndex, x, z);
+        }
+
+        @Override
+        public int color(double value) {
+            return blend(NOISE_LOW, NOISE_HIGH, value);
+        }
+
+        @Override
+        public double brightness(double value) {
+            return clamp(value, 0D, 1D);
+        }
+    }
+
+    /**
+     * The height above the fluid that HYBRID terrain picks biomes by, coloured like the height view.
+     */
+    private record PlacementHeightNoise(NoiseField field, double fluidHeight, MapStyle.HeightRange range) implements PickNoise {
+        @Override
+        public double valueAt(int gridIndex, double x, double z) {
+            return field.at(gridIndex, x, z);
+        }
+
+        @Override
+        public int color(double value) {
+            return heightColor(fluidHeight + value, range);
+        }
+
+        @Override
+        public double brightness(double value) {
+            return clamp((fluidHeight + value - range.lowest()) / Math.max(1D, range.highest() - range.lowest()), 0D, 1D);
+        }
+    }
+
+    /**
+     * The square of world positions one tile samples, including the one pixel ring borrowed from its neighbours.
+     */
+    private record TileGrid(int size, double startX, double startZ, double step, BooleanSupplier cancelled) {
+        double worldX(int gridX) {
+            return startX + gridX * step;
+        }
+
+        double worldZ(int gridZ) {
+            return startZ + gridZ * step;
+        }
+    }
+
+    /**
+     * Labels the biomes and regions one tile meets, asking the shared labels only for ones this tile has not seen yet.
+     */
+    private static final class LabelLookup {
+        private final MapLabels labels;
+        private final IdentityHashMap<Object, Short> seen = new IdentityHashMap<>();
+
+        private LabelLookup(MapLabels labels) {
+            this.labels = labels;
+        }
+
+        short idOf(IrisBiome biome) {
+            if (biome == null) {
+                return MapLabels.NONE;
+            }
+            return seen.computeIfAbsent(biome, subject -> labels.idOf(biome));
+        }
+
+        short idOf(IrisRegion region) {
+            if (region == null) {
+                return MapLabels.NONE;
+            }
+            return seen.computeIfAbsent(region, subject -> labels.idOf(region));
+        }
+    }
+
+    /**
+     * Samples the biome and region of every grid cell in squares, filling a square without sampling its inside when
+     * its corners and centre agree, and splitting it into quarters otherwise.
+     */
+    private static final class IdentitySampler {
+        private final TileGrid grid;
+        private final IdentityShader shader;
+        private final int[] identities;
+        private final boolean[] sampled;
+
+        private IdentitySampler(TileGrid grid, IdentityShader shader) {
+            this.grid = grid;
+            this.shader = shader;
+            this.identities = new int[grid.size() * grid.size()];
+            this.sampled = new boolean[identities.length];
+        }
+
+        void renderAll(int blockPixels) {
+            int size = grid.size();
+            for (int gridZ = 0; gridZ < size; gridZ += blockPixels) {
+                int height = Math.min(blockPixels, size - gridZ);
+                for (int gridX = 0; gridX < size; gridX += blockPixels) {
+                    render(gridX, gridZ, Math.min(blockPixels, size - gridX), height);
+                }
             }
         }
 
-        return image;
+        private void render(int gridX, int gridZ, int width, int height) {
+            checkCancelled(grid.cancelled());
+            if (width == 1 && height == 1) {
+                sample(gridX, gridZ);
+                return;
+            }
+            if (fillIfUniform(gridX, gridZ, width, height)) {
+                return;
+            }
+            int leftWidth = Math.max(1, width / 2);
+            int rightWidth = width - leftWidth;
+            int topHeight = Math.max(1, height / 2);
+            int bottomHeight = height - topHeight;
+            render(gridX, gridZ, leftWidth, topHeight);
+            if (rightWidth > 0) {
+                render(gridX + leftWidth, gridZ, rightWidth, topHeight);
+            }
+            if (bottomHeight > 0) {
+                render(gridX, gridZ + topHeight, leftWidth, bottomHeight);
+                if (rightWidth > 0) {
+                    render(gridX + leftWidth, gridZ + topHeight, rightWidth, bottomHeight);
+                }
+            }
+        }
+
+        private boolean fillIfUniform(int gridX, int gridZ, int width, int height) {
+            int maximumX = gridX + width - 1;
+            int maximumZ = gridZ + height - 1;
+            int identity = sample(gridX, gridZ);
+            boolean uniform = sample(maximumX, gridZ) == identity
+                    && sample(gridX, maximumZ) == identity
+                    && sample(maximumX, maximumZ) == identity
+                    && sample(gridX + width / 2, gridZ + height / 2) == identity;
+            if (!uniform) {
+                return false;
+            }
+            for (int row = gridZ; row <= maximumZ; row++) {
+                int start = row * grid.size() + gridX;
+                Arrays.fill(identities, start, start + width, identity);
+                Arrays.fill(sampled, start, start + width, true);
+            }
+            return true;
+        }
+
+        private int sample(int gridX, int gridZ) {
+            int index = gridZ * grid.size() + gridX;
+            if (!sampled[index]) {
+                identities[index] = shader.identity(grid.worldX(gridX), grid.worldZ(gridZ));
+                sampled[index] = true;
+            }
+            return identities[index];
+        }
+    }
+
+    /**
+     * Terrain heights from samples on a coarse lattice, smoothly interpolated in between. Iris heights are costly to
+     * sample, and shading turns the steps of cheaper shortcuts into visible creases, so a smooth curve through fewer
+     * exact samples looks better and draws an order of magnitude faster than sampling every pixel. The lattice lines
+     * up across tiles, so slopes continue seamlessly from one tile into the next.
+     */
+    private static final class HeightLattice {
+        private static final int LATTICE_PIXELS = 4;
+        private static final int LATTICE_MARGIN = 2;
+
+        private final TileGrid grid;
+        private final ProceduralStream<Double> stream;
+        private final int pointsPerSide;
+        private final double[] points;
+
+        private HeightLattice(TileGrid grid, ProceduralStream<Double> stream) {
+            this.grid = grid;
+            this.stream = stream;
+            this.pointsPerSide = (grid.size() - 2) / LATTICE_PIXELS + LATTICE_MARGIN * 2 + 1;
+            this.points = new double[pointsPerSide * pointsPerSide];
+        }
+
+        double[] interpolatedHeights() {
+            samplePoints();
+            int size = grid.size();
+            double[] heights = new double[size * size];
+            for (int gridZ = 0; gridZ < size; gridZ++) {
+                for (int gridX = 0; gridX < size; gridX++) {
+                    heights[gridZ * size + gridX] = heightAt(gridX - 1, gridZ - 1);
+                }
+            }
+            return heights;
+        }
+
+        // Lattice point 0 sits on the tile's first pixel; the margin covers the border ring and the curve's reach.
+        private void samplePoints() {
+            double latticeStep = grid.step() * LATTICE_PIXELS;
+            double firstX = grid.worldX(1) - LATTICE_MARGIN * latticeStep;
+            double firstZ = grid.worldZ(1) - LATTICE_MARGIN * latticeStep;
+            for (int pointZ = 0; pointZ < pointsPerSide; pointZ++) {
+                checkCancelled(grid.cancelled());
+                for (int pointX = 0; pointX < pointsPerSide; pointX++) {
+                    points[pointZ * pointsPerSide + pointX] = stream.getDouble(firstX + pointX * latticeStep,
+                            firstZ + pointZ * latticeStep);
+                }
+            }
+        }
+
+        private double heightAt(int pixelX, int pixelZ) {
+            int cellX = Math.floorDiv(pixelX, LATTICE_PIXELS);
+            int cellZ = Math.floorDiv(pixelZ, LATTICE_PIXELS);
+            double fractionX = (pixelX - cellX * LATTICE_PIXELS) / (double) LATTICE_PIXELS;
+            double fractionZ = (pixelZ - cellZ * LATTICE_PIXELS) / (double) LATTICE_PIXELS;
+            int baseX = cellX + LATTICE_MARGIN;
+            int baseZ = cellZ + LATTICE_MARGIN;
+            double[] rows = new double[4];
+            for (int row = 0; row < 4; row++) {
+                int offset = (baseZ - 1 + row) * pointsPerSide + baseX - 1;
+                rows[row] = catmullRom(points[offset], points[offset + 1], points[offset + 2], points[offset + 3], fractionX);
+            }
+            return catmullRom(rows[0], rows[1], rows[2], rows[3], fractionZ);
+        }
+
+        private static double catmullRom(double before, double start, double end, double after, double fraction) {
+            double squared = fraction * fraction;
+            double cubed = squared * fraction;
+            return 0.5D * (2D * start
+                    + (end - before) * fraction
+                    + (2D * before - 5D * start + 4D * end - after) * squared
+                    + (3D * start - before - 3D * end + after) * cubed);
+        }
     }
 }

core/src/main/java/com/volmit/iris/core/gui/components/MapLabels.java

@@ -0,0 +1,80 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui.components;
+
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.engine.object.IrisRegion;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Numbers every biome and region the map has drawn, so a tile can remember what each of its pixels shows in two bytes.
+ * One set of labels belongs to one generation of the pack: a hotload starts a new one.
+ */
+public final class MapLabels {
+    public static final short NONE = -1;
+
+    private final IdentityHashMap<Object, Short> idsBySubject = new IdentityHashMap<>();
+    private final Map<String, Short> idsByKey = new HashMap<>();
+    private final List<Label> labels = new ArrayList<>();
+
+    synchronized short idOf(IrisBiome biome) {
+        return idOf(biome, Kind.BIOME, biome.getLoadKey(), biome.getName());
+    }
+
+    synchronized short idOf(IrisRegion region) {
+        return idOf(region, Kind.REGION, region.getLoadKey(), region.getName());
+    }
+
+    public synchronized Label label(short id) {
+        return id < 0 || id >= labels.size() ? null : labels.get(id);
+    }
+
+    public synchronized short idOf(Kind kind, String key) {
+        Short id = idsByKey.get(kind.name() + ':' + key);
+        return id == null ? NONE : id;
+    }
+
+    private short idOf(Object subject, Kind kind, String key, String name) {
+        Short existing = idsBySubject.get(subject);
+        if (existing != null) {
+            return existing;
+        }
+        if (labels.size() >= Short.MAX_VALUE) {
+            return NONE;
+        }
+        short id = (short) labels.size();
+        labels.add(new Label(id, kind, key, name, subject));
+        idsBySubject.put(subject, id);
+        idsByKey.putIfAbsent(kind.name() + ':' + key, id);
+        return id;
+    }
+
+    public enum Kind {
+        BIOME,
+        REGION
+    }
+
+    public record Label(short id, Kind kind, String key, String name, Object subject) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/components/MapLayer.java

@@ -0,0 +1,57 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui.components;
+
+import java.util.Objects;
+
+/**
+ * What a map tile shows: one of the render types, for a region preview which region every spot is treated as, and in
+ * the region and biome views whether the noise that picks is drawn too.
+ *
+ * @param previewRegionKey the region a {@link RenderType#REGION_PREVIEW} tile shows everywhere, null for every other type
+ * @param display          how the picking noise is drawn; only the region and biome views draw anything but the picks
+ */
+public record MapLayer(RenderType type, String previewRegionKey, PickDisplay display) {
+    public MapLayer {
+        Objects.requireNonNull(type, "type");
+        Objects.requireNonNull(display, "display");
+        if ((type == RenderType.REGION_PREVIEW) != (previewRegionKey != null)) {
+            throw new IllegalArgumentException("Only a region preview names a region");
+        }
+        if (display != PickDisplay.PICKS && !type.drawsPickNoise()) {
+            throw new IllegalArgumentException(type + " has no picking noise to draw");
+        }
+    }
+
+    public static MapLayer of(RenderType type) {
+        return new MapLayer(type, null, PickDisplay.PICKS);
+    }
+
+    public static MapLayer biomes(PickDisplay display) {
+        return new MapLayer(RenderType.BIOME, null, display);
+    }
+
+    public static MapLayer regions(PickDisplay display) {
+        return new MapLayer(RenderType.REGION, null, display);
+    }
+
+    public static MapLayer regionPreview(String regionKey, PickDisplay display) {
+        return new MapLayer(RenderType.REGION_PREVIEW, Objects.requireNonNull(regionKey, "regionKey"), display);
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/components/MapStyle.java

@@ -0,0 +1,54 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui.components;
+
+/**
+ * How map tiles are drawn on top of their plain colours: terrain shading, region borders and one highlighted biome or region.
+ *
+ * @param highlight the biome or region to keep bright while everything else dims, or null to show all
+ * @param heightRange the heights the height view spreads its colours over, or null outside the height view
+ */
+public record MapStyle(boolean shading, boolean regionBorders, Highlight highlight, HeightRange heightRange) {
+    public static final MapStyle PLAIN = new MapStyle(false, false, null, null);
+
+    public MapStyle withShading(boolean nextShading) {
+        return new MapStyle(nextShading, regionBorders, highlight, heightRange);
+    }
+
+    public MapStyle withRegionBorders(boolean nextRegionBorders) {
+        return new MapStyle(shading, nextRegionBorders, highlight, heightRange);
+    }
+
+    public MapStyle withHighlight(Highlight nextHighlight) {
+        return new MapStyle(shading, regionBorders, nextHighlight, heightRange);
+    }
+
+    public MapStyle withHeightRange(HeightRange nextHeightRange) {
+        return new MapStyle(shading, regionBorders, highlight, nextHeightRange);
+    }
+
+    public record Highlight(MapLabels.Kind kind, String key, String name) {
+    }
+
+    /**
+     * Water colours run from the lowest height up to sea level, land colours from sea level up to the highest.
+     */
+    public record HeightRange(double lowest, double seaLevel, double highest) {
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/components/MapTile.java

@@ -0,0 +1,226 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui.components;
+
+import com.volmit.iris.core.gui.GuiHost;
+
+import java.awt.image.BufferedImage;
+
+/**
+ * One rendered square of the map. Besides its colours it remembers which biome or region and which region every pixel
+ * shows, and optionally the terrain height, so highlighting, borders, shading and the legend never need a new render.
+ * The label and height grids have a one pixel border taken from the neighbouring tiles, so edges and slopes line up
+ * across tile boundaries.
+ */
+public final class MapTile {
+    private static final double SHADING_EXAGGERATION = 1.2D;
+    private static final double LIGHT_X = -1D;
+    private static final double LIGHT_Y = 1.5D;
+    private static final double LIGHT_Z = -1D;
+    private static final double LIGHT_LENGTH = Math.sqrt(LIGHT_X * LIGHT_X + LIGHT_Y * LIGHT_Y + LIGHT_Z * LIGHT_Z);
+    private static final double FLAT_LIGHT = LIGHT_Y / LIGHT_LENGTH;
+    private static final double DARKEST_SHADE = 0.55D;
+    private static final double BRIGHTEST_SHADE = 1.25D;
+    private static final int DIM_TARGET = 0x1E1F22;
+    private static final double DIM_AMOUNT = 0.72D;
+    private static final double DIM_DESATURATION = 0.6D;
+    private static final int HIGHLIGHT_EDGE = 0xFFFFFF;
+    // A solid outline turns biomes that are scattered pixel by pixel into white noise, so the edge only tints.
+    private static final double HIGHLIGHT_EDGE_STRENGTH = 0.55D;
+    private static final int REGION_BORDER = 0x101114;
+    private static final double REGION_BORDER_STRENGTH = 0.6D;
+
+    private final int size;
+    private final double blocksPerPixel;
+    private final MapLabels labels;
+    private final MapLabels.Kind subjectKind;
+    private final int[] colors;
+    private final MapStyle.HeightRange defaultHeightRange;
+    private final short[] subjects;
+    private final short[] regions;
+    private final double[] heights;
+    private MapStyle styledFor;
+    private BufferedImage styledImage;
+
+    /**
+     * @param colors the colour of every pixel, or null to colour the pixels by their height when they are drawn
+     * @param defaultHeightRange the height colours to use until the map has measured the heights on screen
+     */
+    MapTile(int size, double blocksPerPixel, MapLabels labels, MapLabels.Kind subjectKind, int[] colors,
+            MapStyle.HeightRange defaultHeightRange, short[] subjects, short[] regions, double[] heights) {
+        this.size = size;
+        this.blocksPerPixel = blocksPerPixel;
+        this.labels = labels;
+        this.subjectKind = subjectKind;
+        this.colors = colors;
+        this.defaultHeightRange = defaultHeightRange;
+        this.subjects = subjects;
+        this.regions = regions;
+        this.heights = heights;
+    }
+
+    public int size() {
+        return size;
+    }
+
+    public MapLabels labels() {
+        return labels;
+    }
+
+    /**
+     * Whether the pixels name biomes or, in the region view, regions.
+     */
+    public MapLabels.Kind subjectKind() {
+        return subjectKind;
+    }
+
+    public boolean hasHeights() {
+        return heights != null;
+    }
+
+    public short subjectAt(int pixelX, int pixelZ) {
+        return subjects[gridIndex(pixelX, pixelZ)];
+    }
+
+    public short regionAt(int pixelX, int pixelZ) {
+        return regions[gridIndex(pixelX, pixelZ)];
+    }
+
+    public double heightAt(int pixelX, int pixelZ) {
+        return heights[gridIndex(pixelX, pixelZ)];
+    }
+
+    public long bytes() {
+        long styledBytes = (long) size * size * Integer.BYTES;
+        long gridCells = (long) (size + 2) * (size + 2);
+        long heightBytes = heights == null ? 0L : gridCells * Double.BYTES;
+        long colorBytes = colors == null ? 0L : (long) colors.length * Integer.BYTES;
+        return colorBytes + gridCells * Short.BYTES * 2L + heightBytes + styledBytes;
+    }
+
+    /**
+     * The tile as it looks in the given style; the last style's picture is kept, so redrawing an unchanged map is free.
+     */
+    public synchronized BufferedImage image(MapStyle style) {
+        if (styledImage == null || !style.equals(styledFor)) {
+            styledImage = GuiHost.uncachedImage(styledPixels(style), size, size);
+            styledFor = style;
+        }
+        return styledImage;
+    }
+
+    private int[] styledPixels(MapStyle style) {
+        int[] pixels = new int[size * size];
+        boolean shading = style.shading() && heights != null;
+        short[] highlightGrid = highlightGrid(style.highlight());
+        short highlighted = highlightGrid == null
+                ? MapLabels.NONE
+                : labels.idOf(style.highlight().kind(), style.highlight().key());
+        MapStyle.HeightRange heightRange = style.heightRange() == null ? defaultHeightRange : style.heightRange();
+        for (int pixelZ = 0; pixelZ < size; pixelZ++) {
+            for (int pixelX = 0; pixelX < size; pixelX++) {
+                int color = colors == null
+                        ? IrisRenderer.heightColor(heightAt(pixelX, pixelZ), heightRange)
+                        : colors[pixelZ * size + pixelX];
+                if (shading) {
+                    color = shade(color, pixelX, pixelZ);
+                }
+                if (highlightGrid != null) {
+                    color = highlight(color, highlightGrid, pixelX, pixelZ, highlighted);
+                }
+                if (style.regionBorders() && isRegionEdge(pixelX, pixelZ)) {
+                    color = blend(color, REGION_BORDER, REGION_BORDER_STRENGTH);
+                }
+                pixels[pixelZ * size + pixelX] = color;
+            }
+        }
+        return pixels;
+    }
+
+    // Lit from the north west like a relief map, so slopes read as hills and valleys at a glance.
+    private int shade(int color, int pixelX, int pixelZ) {
+        double slopeX = (height(pixelX + 1, pixelZ) - height(pixelX - 1, pixelZ)) / (2D * blocksPerPixel);
+        double slopeZ = (height(pixelX, pixelZ + 1) - height(pixelX, pixelZ - 1)) / (2D * blocksPerPixel);
+        double normalX = -slopeX * SHADING_EXAGGERATION;
+        double normalZ = -slopeZ * SHADING_EXAGGERATION;
+        double normalLength = Math.sqrt(normalX * normalX + 1D + normalZ * normalZ);
+        double light = (normalX * LIGHT_X + LIGHT_Y + normalZ * LIGHT_Z) / (normalLength * LIGHT_LENGTH);
+        double factor = Math.max(DARKEST_SHADE, Math.min(BRIGHTEST_SHADE, light / FLAT_LIGHT));
+        return scale(color, factor);
+    }
+
+    // Every view knows its regions, so a region can be highlighted in a biome view too.
+    private short[] highlightGrid(MapStyle.Highlight highlight) {
+        if (highlight == null) {
+            return null;
+        }
+        if (highlight.kind() == subjectKind) {
+            return subjects;
+        }
+        return highlight.kind() == MapLabels.Kind.REGION ? regions : null;
+    }
+
+    private int highlight(int color, short[] grid, int pixelX, int pixelZ, short highlighted) {
+        if (grid[gridIndex(pixelX, pixelZ)] != highlighted) {
+            return dim(color);
+        }
+        boolean edge = grid[gridIndex(pixelX + 1, pixelZ)] != highlighted
+                || grid[gridIndex(pixelX - 1, pixelZ)] != highlighted
+                || grid[gridIndex(pixelX, pixelZ + 1)] != highlighted
+                || grid[gridIndex(pixelX, pixelZ - 1)] != highlighted;
+        return edge ? blend(color, HIGHLIGHT_EDGE, HIGHLIGHT_EDGE_STRENGTH) : color;
+    }
+
+    private boolean isRegionEdge(int pixelX, int pixelZ) {
+        short region = regionAt(pixelX, pixelZ);
+        return regions[gridIndex(pixelX + 1, pixelZ)] != region || regions[gridIndex(pixelX, pixelZ + 1)] != region;
+    }
+
+    private double height(int pixelX, int pixelZ) {
+        return heights[gridIndex(pixelX, pixelZ)];
+    }
+
+    // Pixel coordinates run from -1 to size, the outer ring being the neighbouring tiles' edge pixels.
+    private int gridIndex(int pixelX, int pixelZ) {
+        return (pixelZ + 1) * (size + 2) + pixelX + 1;
+    }
+
+    private static int dim(int color) {
+        int red = (color >> 16) & 0xFF;
+        int green = (color >> 8) & 0xFF;
+        int blue = color & 0xFF;
+        int gray = (red + green + blue) / 3;
+        int desaturated = blend(color, (gray << 16) | (gray << 8) | gray, DIM_DESATURATION);
+        return blend(desaturated, DIM_TARGET, DIM_AMOUNT);
+    }
+
+    private static int scale(int color, double factor) {
+        int red = Math.min(255, (int) (((color >> 16) & 0xFF) * factor));
+        int green = Math.min(255, (int) (((color >> 8) & 0xFF) * factor));
+        int blue = Math.min(255, (int) ((color & 0xFF) * factor));
+        return (red << 16) | (green << 8) | blue;
+    }
+
+    static int blend(int first, int second, double amount) {
+        int red = (int) Math.round(((first >> 16) & 0xFF) * (1D - amount) + ((second >> 16) & 0xFF) * amount);
+        int green = (int) Math.round(((first >> 8) & 0xFF) * (1D - amount) + ((second >> 8) & 0xFF) * amount);
+        int blue = (int) Math.round((first & 0xFF) * (1D - amount) + (second & 0xFF) * amount);
+        return (red << 16) | (green << 8) | blue;
+    }
+}