Port the v3 map as iris std map

- iris std map opens the v3 map window; noise, palettes, objects, procedural and image maps are views in it
- Rivers view draws v4 hydrology, with an empty state when the pack has rivers off
- 3D views fall back to software when LWJGL isn't on the classpath; modded jars use the game's LWJGL
- FlatLaf and LWJGL join core; v4's separate studio windows are removed

adapters/bukkit/plugin/src/main/java/art/arcane/iris/Iris.java

@@ -60,6 +60,7 @@ import art.arcane.iris.integration.MultiverseCoreLink;
 import art.arcane.iris.platform.bukkit.nms.INMS;
 import art.arcane.volmlib.nativelib.terrain.ServerShutdownBoundary;
 import art.arcane.iris.studio.view.BukkitGuiHost;
+import art.arcane.iris.studio.view.GuiHost;
 import art.arcane.iris.studio.view.PregeneratorJob;
 import art.arcane.iris.platform.bukkit.BoardSVC;
 import art.arcane.iris.command.CommandSVC;
@@ -988,6 +989,7 @@ public class Iris extends VolmitPlugin implements Listener, ReloadAware {
     }
 
     public void onDisable() {
+        GuiHost.shutdown();
         preservePendingBlockDrops();
         papiLifecycleActive = false;
         if (updateNotifier != null) {

adapters/bukkit/plugin/src/main/java/art/arcane/iris/command/CommandStudio.java

@@ -21,10 +21,10 @@ package art.arcane.iris.command;
 import art.arcane.iris.Iris;
 import art.arcane.iris.platform.bukkit.BukkitPlatform;
 import art.arcane.iris.configuration.IrisSettings;
+import art.arcane.iris.studio.map.MapWindow;
+import art.arcane.iris.studio.map.NoiseExplorerGUI;
+import art.arcane.iris.studio.map.PaletteExplorerStart;
 import art.arcane.iris.studio.view.GuiHost;
-import art.arcane.iris.studio.view.ImageMapStudioGUI;
-import art.arcane.iris.studio.view.NoiseExplorerGUI;
-import art.arcane.iris.studio.view.VisionGUI;
 import art.arcane.iris.pack.loading.IrisData;
 import art.arcane.iris.studio.workspace.IrisProject;
 import art.arcane.iris.studio.workspace.IrisCodeWorkspace;
@@ -255,15 +255,19 @@ public class CommandStudio implements DirectorExecutor {
             long seed
     ) {
         if (noGUI()) return;
-        sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_OPENING_NOISE_EXPLORER));
-
-        if (generator == null) {
-            NoiseExplorerGUI.launch();
+        Engine playerEngine = engine();
+        Engine engine = playerEngine != null ? playerEngine : GuiHost.get().findActiveEngine();
+        if (generator != null) {
+            sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_OPENING_NOISE_EXPLORER));
+            NoiseExplorerGUI.launchGeneratorKey(engine, generator.getLoadKey(), generator, seed);
             return;
         }
-
-        String generatorKey = generator.getLoadKey();
-        NoiseExplorerGUI.launchGeneratorKey(generatorKey, generator, seed);
+        if (engine == null) {
+            sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_YOU_NEED_BE_SPECIFY_IRIS_GENERATED_WORLD));
+            return;
+        }
+        sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_OPENING_NOISE_EXPLORER));
+        MapWindow.openNoise(playerEngine != null ? mapStartIn(player().getWorld()) : mapStartWithoutWorld(engine));
     }
 
     @Director(description = "Open the image-map studio (External GUI)", descriptionKey = "iris.director.commandstudio.director.open_image_map_studio_external_gui", aliases = {"imap"})
@@ -279,8 +283,7 @@ public class CommandStudio implements DirectorExecutor {
             return;
         }
 
-        Engine activeEngine = IrisToolbelt.access(world).getEngine();
-        ImageMapStudioGUI.launch(activeEngine);
+        MapWindow.openImageMaps(mapStartIn(world));
         sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_OPENING_IMAGE_MAP_STUDIO));
     }
 
@@ -420,11 +423,27 @@ public class CommandStudio implements DirectorExecutor {
             return;
         }
 
-        UUID openerId = sender().isPlayer() ? player().getUniqueId() : null;
-        VisionGUI.launch(IrisToolbelt.access(world).getEngine(), openerId);
+        MapWindow.openMap(mapStartIn(world));
         sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_OPENING_MAP));
     }
 
+    // The map opens where the player stands when they are in that world, otherwise at the world origin.
+    private PaletteExplorerStart mapStartIn(World world) {
+        Location center = sender().isPlayer() && player().getWorld().equals(world) ? player().getLocation() : null;
+        return new PaletteExplorerStart(
+                IrisToolbelt.access(world).getEngine(),
+                world.getUID(),
+                sender().isPlayer() ? player().getUniqueId() : null,
+                null,
+                center == null ? 0D : center.getX(),
+                center == null ? 0D : center.getZ()
+        );
+    }
+
+    private PaletteExplorerStart mapStartWithoutWorld(Engine engine) {
+        return new PaletteExplorerStart(engine, null, sender().isPlayer() ? player().getUniqueId() : null, null, 0D, 0D);
+    }
+
     @Director(description = "Profiles the performance of a dimension", descriptionKey = "iris.director.commandstudio.director.profiles_performance_dimension", origin = DirectorOrigin.PLAYER)
     public void profile(
             @Param(description = "The dimension to profile", descriptionKey = "iris.director.commandstudio.param.dimension_profile", contextual = true, contextualOverride = true, defaultValue = "default", customHandler = DimensionHandler.class)

adapters/bukkit/plugin/src/main/java/art/arcane/iris/studio/view/BukkitGuiHost.java

@@ -23,6 +23,8 @@ import art.arcane.iris.world.event.IrisEngineHotloadEvent;
 import art.arcane.iris.world.IrisToolbelt;
 import art.arcane.iris.generation.runtime.Engine;
 import art.arcane.iris.platform.generation.PlatformChunkGenerator;
+import art.arcane.iris.studio.StudioSVC;
+import art.arcane.iris.studio.workspace.IrisProject;
 import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.event.EventHandler;
@@ -40,16 +42,21 @@ public final class BukkitGuiHost implements GuiHost.Provider {
         GuiHost.set(new BukkitGuiHost());
     }
 
+    /**
+     * The engine of the open studio project, which reads the pack folder being edited, or else the first
+     * Iris world. A normal Iris world runs on its own copy of the pack, made when the world was created.
+     */
     @Override
     public Engine findActiveEngine() {
+        Engine studioEngine = findStudioEngine();
+        if (studioEngine != null) {
+            return studioEngine;
+        }
         try {
             for (World world : new ArrayList<>(Bukkit.getWorlds())) {
-                try {
-                    PlatformChunkGenerator access = IrisToolbelt.access(world);
-                    if (access != null && access.getEngine() != null && !access.getEngine().isClosed()) {
-                        return access.getEngine();
-                    }
-                } catch (Throwable ignored) {
+                Engine engine = engineOf(world);
+                if (engine != null) {
+                    return engine;
                 }
             }
         } catch (Throwable ignored) {
@@ -57,6 +64,35 @@ public final class BukkitGuiHost implements GuiHost.Provider {
         return null;
     }
 
+    @Override
+    public Engine findEngine(UUID worldId) {
+        World world = worldId == null ? null : Bukkit.getWorld(worldId);
+        return world == null ? null : engineOf(world);
+    }
+
+    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;
+        }
+    }
+
+    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;
+    }
+
     @Override
     public void registerHotloadHook(Runnable onHotload) {
         Listener listener = new HotloadListener(onHotload);

adapters/bukkit/plugin/src/main/java/art/arcane/iris/studio/view/BukkitVisionOverlay.java

@@ -18,23 +18,19 @@
 
 package art.arcane.iris.studio.view;
 
-import art.arcane.volmlib.nativelib.view.WorldMarker;
-
-import art.arcane.iris.generation.runtime.IrisComplex;
 import art.arcane.iris.generation.runtime.Engine;
-import art.arcane.iris.studio.render.RenderType;
 import art.arcane.iris.world.IrisWorld;
 import art.arcane.iris.platform.bukkit.BukkitPlatform;
 import art.arcane.iris.platform.bukkit.BukkitWorldBinding;
 import art.arcane.iris.spi.IrisLogging;
 import art.arcane.iris.world.task.J;
 import art.arcane.volmlib.util.format.Form;
+import org.bukkit.Bukkit;
 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.Collections;
 import java.util.List;
@@ -56,7 +52,7 @@ public final class BukkitVisionOverlay implements GuiOverlay {
     private final AtomicBoolean playerRefreshQueued = new AtomicBoolean();
     private final AtomicLong teleportSequence = new AtomicLong();
     private final AtomicReference<VisionTeleportRequest> latestTeleport = new AtomicReference<>();
-    private volatile List<WorldMarker> playerMarkers = List.of();
+    private volatile List<GuiMarker> playerMarkers = List.of();
 
     public BukkitVisionOverlay(Engine engine, UUID openerId) {
         this.engine = engine;
@@ -68,7 +64,7 @@ public final class BukkitVisionOverlay implements GuiOverlay {
      * built by a server thread.
      */
     @Override
-    public List<WorldMarker> players() {
+    public List<GuiMarker> players() {
         queuePlayerRefresh();
         return playerMarkers;
     }
@@ -80,10 +76,10 @@ public final class BukkitVisionOverlay implements GuiOverlay {
 
         boolean scheduled = J.runGlobal(() -> {
             try {
-                List<WorldMarker> markers = new ArrayList<>();
+                List<GuiMarker> markers = new ArrayList<>();
                 for (Player player : BukkitWorldBinding.players(engine.getWorld())) {
                     Location at = player.getLocation();
-                    markers.add(WorldMarker.player(player.getName(), at.getX(), at.getZ()));
+                    markers.add(GuiMarker.player(player.getName(), at.getX(), at.getZ(), at.getYaw()));
                 }
                 playerMarkers = List.copyOf(markers);
             } finally {
@@ -97,7 +93,7 @@ public final class BukkitVisionOverlay implements GuiOverlay {
     }
 
     @Override
-    public void requestEntities(Consumer<List<WorldMarker>> sink) {
+    public void requestEntities(Consumer<List<GuiMarker>> sink) {
         J.runGlobal(() -> {
             IrisWorld target = engine.getWorld();
             World world = BukkitWorldBinding.world(target);
@@ -118,7 +114,7 @@ public final class BukkitVisionOverlay implements GuiOverlay {
                 return;
             }
 
-            List<WorldMarker> collected = Collections.synchronizedList(new ArrayList<>(living.size()));
+            List<GuiMarker> collected = Collections.synchronizedList(new ArrayList<>(living.size()));
             AtomicInteger pending = new AtomicInteger(living.size());
             Runnable complete = () -> {
                 if (pending.decrementAndGet() == 0) {
@@ -144,22 +140,22 @@ public final class BukkitVisionOverlay implements GuiOverlay {
         });
     }
 
-    private WorldMarker marker(LivingEntity entity, Location at) {
+    private GuiMarker marker(LivingEntity entity, Location at) {
         String label = Form.capitalizeWords(entity.getType().name().toLowerCase(Locale.ROOT).replaceAll("\\Q_\\E", " "));
         double maxHealth = 0;
         try {
             maxHealth = entity.getAttribute(MAX_HEALTH).getValue();
         } catch (Throwable ignored) {
         }
-        return WorldMarker.entity(label, at.getX(), at.getY(), at.getZ(), entity.getHealth(), maxHealth);
+        return GuiMarker.entity(label, at.getX(), at.getY(), at.getZ(), entity.getHealth(), maxHealth);
     }
 
     @Override
     public void teleport(double worldX, double worldZ) {
         VisionTeleportRequest request = new VisionTeleportRequest(
                 teleportSequence.incrementAndGet(),
-                VisionGUI.floorWorldCoordinate(worldX),
-                VisionGUI.floorWorldCoordinate(worldZ));
+                (int) StrictMath.floor(worldX),
+                (int) StrictMath.floor(worldZ));
         latestTeleport.set(request);
         startTeleport(request);
     }
@@ -212,6 +208,36 @@ public final class BukkitVisionOverlay implements GuiOverlay {
         }
     }
 
+    @Override
+    public void requestOpenerPosition(Consumer<OpenerPosition> sink) {
+        if (openerId == null) {
+            sink.accept(OpenerPosition.OFFLINE);
+            return;
+        }
+        boolean scheduled = J.runGlobal(() -> {
+            Player player = Bukkit.getPlayer(openerId);
+            if (player == null) {
+                sink.accept(OpenerPosition.OFFLINE);
+                return;
+            }
+            World world = BukkitWorldBinding.world(engine.getWorld());
+            if (!J.runEntity(player, () -> sink.accept(positionOf(player, world)))) {
+                sink.accept(OpenerPosition.OFFLINE);
+            }
+        });
+        if (!scheduled) {
+            sink.accept(OpenerPosition.OFFLINE);
+        }
+    }
+
+    private static OpenerPosition positionOf(Player player, World world) {
+        if (world == null || player.getWorld() != world) {
+            return OpenerPosition.IN_OTHER_WORLD;
+        }
+        Location at = player.getLocation();
+        return OpenerPosition.inWorld(at.getX(), at.getY(), at.getZ());
+    }
+
     private Player selectPlayer(List<Player> players) {
         if (openerId == null) {
             return players.isEmpty() ? null : players.get(0);
@@ -316,21 +342,6 @@ public final class BukkitVisionOverlay implements GuiOverlay {
                 + blockX + "," + blockZ + ".", failure);
     }
 
-    @Override
-    public String openInEditor(double worldX, double worldZ, RenderType type) {
-        IrisComplex complex = engine.getComplex();
-        File file = switch (type) {
-            case BIOME, LAYER_LOAD, DECORATOR_LOAD, OBJECT_LOAD, HEIGHT, RIVER ->
-                    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 CAVE_LAND -> complex.getCaveBiomeStream().get(worldX, worldZ).openInVSCode();
-            default -> null;
-        };
-        return file == null ? null : file.getName();
-    }
-
     private static final class VisionTeleportRequest {
         private final long sequence;
         private final int blockX;

adapters/fabric/build.gradle

@@ -131,6 +131,8 @@ configurations.named('bundle').configure {
     exclude(group: 'de.crazydev22.slimjar.helper')
     exclude(group: 'de.crazydev22.slimjar')
     exclude(group: 'io.github.slimjar')
+    // The game ships its own LWJGL; without the modules it leaves out, the map's 3D views draw in software.
+    exclude(group: 'org.lwjgl')
 }
 
 configurations.compileClasspath.extendsFrom(configurations.devBundle)
@@ -216,7 +218,9 @@ dependencies {
         libs.caffeine,
         'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
-        libs.jaxen
+        libs.jaxen,
+        libs.flatlaf,
+        libs.flatlaf.extras
     ]
     shared.each { Object notation ->
         ['bundle', 'devBundle'].each { String configuration ->

adapters/forge/build.gradle

@@ -152,12 +152,16 @@ configurations.named('bundle').configure {
     exclude(group: 'de.crazydev22.slimjar.helper')
     exclude(group: 'de.crazydev22.slimjar')
     exclude(group: 'io.github.slimjar')
+    // The game ships its own LWJGL; without the modules it leaves out, the map's 3D views draw in software.
+    exclude(group: 'org.lwjgl')
 }
 
 configurations.named('runBundle').configure {
     exclude(group: 'de.crazydev22.slimjar.helper')
     exclude(group: 'de.crazydev22.slimjar')
     exclude(group: 'io.github.slimjar')
+    // The game ships its own LWJGL; without the modules it leaves out, the map's 3D views draw in software.
+    exclude(group: 'org.lwjgl')
 }
 
 configurations.compileClasspath.extendsFrom(configurations.devBundle)
@@ -215,7 +219,9 @@ dependencies {
         libs.caffeine,
         'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
-        libs.jaxen
+        libs.jaxen,
+        libs.flatlaf,
+        libs.flatlaf.extras
     ]
     shared.each { Object notation ->
         ['bundle', 'devBundle', 'runBundle'].each { String configuration ->

adapters/modded-common/src/main/java/art/arcane/iris/modded/ModdedEngineBootstrap.java

@@ -227,6 +227,7 @@ public final class ModdedEngineBootstrap {
         failure = runStopStage(failure, "wand service", ModdedWandService::clearAll);
         failure = runStopStage(failure, "block break handler", ModdedBlockBreakHandler::clear);
         failure = runStopStage(failure, "studio commands", ModdedStudioCommands::clear);
+        failure = runStopStage(failure, "gui windows", GuiHost::shutdown);
         failure = runStopStage(failure, "gui host", ModdedGuiHost::clear);
         failure = runStopStage(failure, "services", () -> services().disableAll());
         reportStopFailure("stopping", failure);

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedStudioCommands.java

@@ -23,10 +23,10 @@ import art.arcane.volmlib.nativelib.minecraft26_2.modded.NativeWorldView;
 
 import art.arcane.iris.modded.ModdedIrisLog;
 import art.arcane.iris.configuration.IrisSettings;
+import art.arcane.iris.studio.map.MapWindow;
+import art.arcane.iris.studio.map.NoiseExplorerGUI;
+import art.arcane.iris.studio.map.PaletteExplorerStart;
 import art.arcane.iris.studio.view.GuiHost;
-import art.arcane.iris.studio.view.ImageMapStudioGUI;
-import art.arcane.iris.studio.view.NoiseExplorerGUI;
-import art.arcane.iris.studio.view.VisionGUI;
 import art.arcane.iris.pack.loading.IrisData;
 import art.arcane.iris.pack.StructurePackageClosure;
 import art.arcane.iris.pack.ImageMapPackageClosure;
@@ -247,8 +247,9 @@ public final class ModdedStudioCommands {
             NativeProtocolPlayer player = source.player();
             ModdedGuiHost.bindContext(worldView(source.server(), level), engine, player == null ? null : player.id());
         }
-        if (generatorKey == null || generatorKey.isBlank()) {
-            NoiseExplorerGUI.launch();
+        Engine mapEngine = engine != null ? engine : GuiHost.get().findActiveEngine();
+        if ((generatorKey == null || generatorKey.isBlank()) && mapEngine != null) {
+            MapWindow.openNoise(mapStart(mapEngine, source.player()));
             IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_OPENING_NOISE_EXPLORER_ON_SERVER_DISPLAY));
             return 1;
         }
@@ -262,7 +263,7 @@ public final class ModdedStudioCommands {
             return 0;
         }
         String selectedGeneratorKey = generatorKey.trim();
-        NoiseExplorerGUI.launchGeneratorKey(selectedGeneratorKey, generator, seed);
+        NoiseExplorerGUI.launchGeneratorKey(engine, selectedGeneratorKey, generator, seed);
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_OPENING_NOISE_EXPLORER_GENERATOR_SEED, MessageArgument.untrusted("value", generatorKey.trim()), MessageArgument.untrusted("seed", seed)));
         return 1;
     }
@@ -280,11 +281,16 @@ public final class ModdedStudioCommands {
         }
         NativeProtocolPlayer player = source.player();
         ModdedGuiHost.bindContext(worldView(source.server(), level), engine, player == null ? null : player.id());
-        VisionGUI.launch(engine, player == null ? null : player.id());
+        MapWindow.openMap(mapStart(engine, player));
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_OPENING_VISION_MAP_ON_SERVER_DISPLAY, MessageArgument.untrusted("value", level.name())));
         return 1;
     }
 
+    // Modded worlds have no Bukkit world id; the map finds the engine again through the bound GUI context.
+    private static PaletteExplorerStart mapStart(Engine engine, NativeProtocolPlayer player) {
+        return new PaletteExplorerStart(engine, null, player == null ? null : player.id(), null, 0D, 0D);
+    }
+
     private static int imageMap(NativeCommandSource source) {
         NativeWorld level = source.world();
         Engine engine = IrisModdedCommands.engineFor(level);
@@ -294,13 +300,13 @@ public final class ModdedStudioCommands {
             ));
             return 0;
         }
-        if (!ImageMapStudioGUI.isAvailable()) {
+        if (!GuiHost.isAvailable() || !IrisSettings.get().getGui().isUseServerLaunchedGuis()) {
             IrisModdedCommands.fail(source, guiUnavailableMessage());
             return 0;
         }
         NativeProtocolPlayer player = source.player();
         ModdedGuiHost.bindContext(worldView(source.server(), level), engine, player == null ? null : player.id());
-        ImageMapStudioGUI.launch(engine);
+        MapWindow.openImageMaps(mapStart(engine, player));
         IrisModdedCommands.ok(source, IrisLanguage.plain(
                 ModdedCommandMessages.MODDED_STUDIO_COMMANDS_OPENING_IMAGE_MAP_STUDIO_ON_SERVER_DISPLAY,
                 MessageArgument.untrusted("value", level.name())

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedVisionOverlay.java

@@ -18,17 +18,12 @@
 
 package art.arcane.iris.modded.command;
 
-import art.arcane.iris.studio.view.GuiHost;
-import art.arcane.volmlib.nativelib.view.WorldMarker;
+import art.arcane.iris.studio.view.GuiMarker;
 import art.arcane.iris.studio.view.GuiOverlay;
-import art.arcane.iris.generation.runtime.IrisComplex;
 import art.arcane.iris.generation.runtime.Engine;
-import art.arcane.iris.studio.render.RenderType;
 import art.arcane.iris.modded.ModdedIrisLog;
 import art.arcane.iris.modded.ModdedTeleportDeadline;
 
-import java.awt.Desktop;
-import java.io.File;
 import java.util.List;
 import java.util.Optional;
 import art.arcane.volmlib.nativelib.view.WorldView;
@@ -46,14 +41,20 @@ public final class ModdedVisionOverlay implements GuiOverlay {
         opener = context.opener();
     }
 
+    // WorldView doesn't report which way a player faces, so their markers all face south.
     @Override
-    public List<WorldMarker> players() {
-        return world.players();
+    public List<GuiMarker> players() {
+        return world.players().stream()
+                .map(player -> GuiMarker.player(player.label(), player.worldX(), player.worldZ(), 0F))
+                .toList();
     }
 
     @Override
-    public void requestEntities(Consumer<List<WorldMarker>> sink) {
-        world.requestEntities(sink);
+    public void requestEntities(Consumer<List<GuiMarker>> sink) {
+        world.requestEntities(entities -> sink.accept(entities.stream()
+                .map(entity -> GuiMarker.entity(entity.label(), entity.worldX(), entity.worldY(), entity.worldZ(),
+                        entity.health(), entity.maxHealth()))
+                .toList()));
     }
 
     @Override
@@ -80,23 +81,6 @@ public final class ModdedVisionOverlay implements GuiOverlay {
         });
     }
 
-    @Override
-    public String openInEditor(double worldX, double worldZ, RenderType type) {
-        if (!GuiHost.isAvailable() || !Desktop.isDesktopSupported()) {
-            return null;
-        }
-        IrisComplex complex = engine.getComplex();
-        File file = switch (type) {
-            case BIOME, LAYER_LOAD, DECORATOR_LOAD, OBJECT_LOAD, HEIGHT, RIVER ->
-                    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 CAVE_LAND -> complex.getCaveBiomeStream().get(worldX, worldZ).openInVSCode();
-            default -> null;
-        };
-        return file == null ? null : file.getName();
-    }
     public record Context(WorldView world, Engine engine, UUID opener) {
     }
 

adapters/neoforge/build.gradle

@@ -132,6 +132,8 @@ configurations.named('bundle').configure {
     exclude(group: 'de.crazydev22.slimjar.helper')
     exclude(group: 'de.crazydev22.slimjar')
     exclude(group: 'io.github.slimjar')
+    // The game ships its own LWJGL; without the modules it leaves out, the map's 3D views draw in software.
+    exclude(group: 'org.lwjgl')
 }
 
 configurations.compileClasspath.extendsFrom(configurations.devBundle)
@@ -173,7 +175,9 @@ dependencies {
         libs.caffeine,
         'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
-        libs.jaxen
+        libs.jaxen,
+        libs.flatlaf,
+        libs.flatlaf.extras
     ]
     add('bundle', libs.asm)
     add('devBundle', 'org.ow2.asm:asm') {

core/build.gradle

@@ -136,6 +136,13 @@ dependencies {
     implementation('com.moandjiezana.toml:toml4j:0.7.2') {
         transitive = false
     }
+    // Shaded: the runtime downloader can neither fetch the natives classifiers nor relocate lwjgl's own jar.
+    implementation(libs.lwjgl)
+    implementation(libs.lwjgl.opengl)
+    implementation(libs.lwjgl.egl)
+    implementation(libs.lwjgl.jawt)
+    runtimeOnly(variantOf(libs.lwjgl) { classifier('natives-linux') })
+    runtimeOnly(variantOf(libs.lwjgl.opengl) { classifier('natives-linux') })
     // Dynamically Loaded
     slim(libs.gson)
     slim(libs.lru)
@@ -161,6 +168,8 @@ dependencies {
     slim(libs.byteBuddy.agent)
     slim(libs.dom4j)
     slim(libs.jaxen)
+    slim(libs.flatlaf)
+    slim(libs.flatlaf.extras)
 
     testFixturesImplementation('junit:junit:4.13.2')
     testFixturesImplementation('org.mockito:mockito-core:5.23.0')

core/src/main/java/art/arcane/iris/configuration/IrisSettings.java

@@ -373,6 +373,7 @@ public class IrisSettings {
         public boolean useServerLaunchedGuis = true;
         public boolean maximumPregenGuiFPS = false;
         public boolean colorMode = true;
+        public String theme = "auto";
     }
 
     @Data

core/src/main/java/art/arcane/iris/generation/biome/IrisBiome.java

@@ -580,6 +580,10 @@ public class IrisBiome extends IrisRegistrant implements Rarity {
         return IrisBiomeLayerGenerator.getLayerSeaHeightGenerators(this, rng, data);
     }
 
+    public KList<CNG> getCaveCeilingLayerHeightGenerators(RNG rng, IrisData data) {
+        return IrisBiomeLayerGenerator.getCaveCeilingLayerHeightGenerators(this, rng, data);
+    }
+
     public NativeBlockState getSurfaceBlock(int x, int z, RNG rng, IrisData idm) {
         return IrisBiomeLayerGenerator.getSurfaceBlock(this, x, z, rng, idm);
     }

core/src/main/java/art/arcane/iris/generation/biome/IrisBiomeLayerGenerator.java

@@ -148,8 +148,7 @@ final class IrisBiomeLayerGenerator {
             return data;
         }
 
-        KList<CNG> heightGenerators = getHeightGenerators(
-                biome.getLayerCeilingHeightGenerators(), ceilingLayers, 7235, random, rdata);
+        KList<CNG> heightGenerators = getCaveCeilingLayerHeightGenerators(biome, random, rdata);
 
         for (int i = 0; i < layerCount; i++) {
             IrisBiomePaletteLayer layer = ceilingLayers.get(i);
@@ -317,6 +316,10 @@ final class IrisBiomeLayerGenerator {
         return getHeightGenerators(biome.getLayerSeaHeightGenerators(), biome.getSeaLayers(), 7735, rng, data);
     }
 
+    static KList<CNG> getCaveCeilingLayerHeightGenerators(IrisBiome biome, RNG rng, IrisData data) {
+        return getHeightGenerators(biome.getLayerCeilingHeightGenerators(), biome.getCaveCeilingLayers(), 7235, rng, data);
+    }
+
     private static KList<CNG> getHeightGenerators(IrisBiomeLayerHeightCache cache,
                                                   KList<IrisBiomePaletteLayer> layers,
                                                   int seedOffset, RNG rng, IrisData data) {

core/src/main/java/art/arcane/iris/generation/runtime/IrisComplex.java

@@ -1176,33 +1176,118 @@ public class IrisComplex implements DataProvider {
             InferredType inferredType,
             IrisBiome emptyBiome
     ) {
+        ProceduralStream<IrisBiome> picked = new RarityStream<>(biomePickNoiseStream(engine.getDimension(), region, inferredType),
+                loadInferredBiomes(biomeKeys(region, inferredType), inferredType));
+        return inferredType == InferredType.CAVE ? picked.onNull(emptyBiome) : picked;
+    }
+
+    private ProceduralStream<Double> biomePickNoiseStream(IrisDimension dimension, IrisRegion region, InferredType inferredType) {
         return switch (inferredType) {
-            case CAVE -> new RarityStream<>(engine.getDimension().getCaveBiomeStyle()
+            case CAVE -> dimension.getCaveBiomeStyle()
                     .create(rng.nextParallelRNG(InferredType.CAVE.ordinal()), getData()).stream()
-                    .zoom(engine.getDimension().getBiomeZoom())
-                    .zoom(region.getCaveBiomeZoom()),
-                    loadInferredBiomes(region.getCaveBiomes(), InferredType.CAVE))
-                    .onNull(emptyBiome);
-            case LAND -> new RarityStream<>(engine.getDimension().getLandBiomeStyle()
+                    .zoom(dimension.getBiomeZoom())
+                    .zoom(region.getCaveBiomeZoom());
+            case LAND -> dimension.getLandBiomeStyle()
                     .create(rng.nextParallelRNG(InferredType.LAND.ordinal()), getData()).stream()
-                    .zoom(engine.getDimension().getBiomeZoom())
-                    .zoom(engine.getDimension().getLandZoom())
-                    .zoom(region.getLandBiomeZoom()),
-                    loadInferredBiomes(region.getLandBiomes(), InferredType.LAND));
-            case SEA -> new RarityStream<>(engine.getDimension().getSeaBiomeStyle()
+                    .zoom(dimension.getBiomeZoom())
+                    .zoom(dimension.getLandZoom())
+                    .zoom(region.getLandBiomeZoom());
+            case SEA -> dimension.getSeaBiomeStyle()
                     .create(rng.nextParallelRNG(InferredType.SEA.ordinal()), getData()).stream()
-                    .zoom(engine.getDimension().getBiomeZoom())
-                    .zoom(engine.getDimension().getSeaZoom())
-                    .zoom(region.getSeaBiomeZoom()),
-                    loadInferredBiomes(region.getSeaBiomes(), InferredType.SEA));
-            case SHORE -> new RarityStream<>(engine.getDimension().getShoreBiomeStyle()
+                    .zoom(dimension.getBiomeZoom())
+                    .zoom(dimension.getSeaZoom())
+                    .zoom(region.getSeaBiomeZoom());
+            case SHORE -> dimension.getShoreBiomeStyle()
                     .create(rng.nextParallelRNG(InferredType.SHORE.ordinal()), getData()).stream()
-                    .zoom(engine.getDimension().getBiomeZoom())
-                    .zoom(region.getShoreBiomeZoom()),
-                    loadInferredBiomes(region.getShoreBiomes(), InferredType.SHORE));
+                    .zoom(dimension.getBiomeZoom())
+                    .zoom(region.getShoreBiomeZoom());
         };
     }
 
+    private static KList<String> biomeKeys(IrisRegion region, InferredType inferredType) {
+        return switch (inferredType) {
+            case CAVE -> region.getCaveBiomes();
+            case LAND -> region.getLandBiomes();
+            case SEA -> region.getSeaBiomes();
+            case SHORE -> region.getShoreBiomes();
+        };
+    }
+
+    /**
+     * The noise that picks one of the region's biomes of this type, before rarity splits it. Image maps and the
+     * studio biome buffet bypass it.
+     */
+    public ProceduralStream<Double> biomePickNoiseStream(IrisRegion region, InferredType inferredType) {
+        return biomePickNoiseStream(terrainEngine.getDimension(), region, inferredType);
+    }
+
+    public double biomePickNoise(IrisRegion region, InferredType inferredType, double x, double z) {
+        return biomePickNoiseStream(region, inferredType).getDouble(x, z);
+    }
+
+    /**
+     * The region's biomes of this type in the order their rarities split the picking noise.
+     */
+    public KList<IrisBiome> noisePickedBiomes(IrisRegion region, InferredType inferredType) {
+        return loadInferredBiomes(biomeKeys(region, inferredType), inferredType);
+    }
+
+    /**
+     * The biome the noise picks from the region's biomes of this type, before child biomes or the coast replace it.
+     */
+    public IrisBiome biomePickedByNoise(IrisRegion region, InferredType inferredType, double x, double z) {
+        return createInferredBiomeStream(region, inferredType).get(x, z);
+    }
+
+    /**
+     * The dimension's regions in the order their rarities split the region noise.
+     */
+    public KList<IrisRegion> noisePickedRegions() {
+        KList<IrisRegion> regions = new KList<>();
+        for (IrisRegion region : data.getRegionLoader().loadAll(terrainEngine.getDimension().getRegions())) {
+            if (!region.isCompatExcluded()) {
+                regions.add(region);
+            }
+        }
+        return regions;
+    }
+
+    /**
+     * The base biome a spot gets in the given region, before the terrain height can move it to another biome list,
+     * and the list it was picked from.
+     */
+    public BiomePick basePickIn(IrisRegion region, double x, double z) {
+        if (focusBiome != null) {
+            return new BiomePick(focusBiome, focusBiome.getInferredType());
+        }
+        InferredType type = bridgeStream.get(x, z);
+        return new BiomePick(implode(createInferredBiomeStream(region, type).get(x, z), x, z), type);
+    }
+
+    /**
+     * The surface biome a spot would get if it belonged to the given region, and the biome list it came from, for
+     * previewing one region across the map.
+     */
+    public BiomePick surfacePickAsIfIn(IrisRegion region, double x, double z) {
+        BiomePick base = basePickIn(region, x, z);
+        if (focusBiome != null) {
+            return base;
+        }
+        IrisBiome surface = resolveSurfaceBiome(heightStream.getDouble(x, z), base.biome(), region, x, z, fluidHeight,
+                createInferredBiomeStream(region, InferredType.LAND),
+                createInferredBiomeStream(region, InferredType.SEA),
+                createInferredBiomeStream(region, InferredType.SHORE),
+                shoreSlopeStream);
+        return surface == base.biome() ? base : new BiomePick(implode(surface, x, z), surface.getInferredType());
+    }
+
+    public IrisBiome surfaceBiomeAsIfIn(IrisRegion region, double x, double z) {
+        return surfacePickAsIfIn(region, x, z).biome();
+    }
+
+    public record BiomePick(IrisBiome biome, InferredType type) {
+    }
+
     private static boolean hydrologyActive(IrisHydrology hydrology) {
         if (hydrology == null) {
             return false;

core/src/main/java/art/arcane/iris/studio/map/BakeMeter.java

@@ -0,0 +1,154 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import com.formdev.flatlaf.extras.FlatSVGIcon;
+
+import javax.swing.JComponent;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+
+/**
+ * IntelliJ's profiler gauge, how heavy the measured bake is, a meter and the time it took, all in the weight's colour.
+ */
+final class BakeMeter extends JComponent {
+    private static final long serialVersionUID = 4120925066373218716L;
+    private static final String PROFILER_ICON = "iris/icons/profiler.svg";
+    private static final String TIMING_LABEL = "Timing";
+    private static final String WIDEST_TIME = "999 ms";
+    private static final int ICON_SIZE = 16;
+    private static final int GAP = 6;
+    private static final int BAR_HEIGHT = 4;
+    private static final int HEIGHT = 20;
+
+    private final FlatSVGIcon icon = new FlatSVGIcon(PROFILER_ICON, ICON_SIZE, ICON_SIZE, BakeMeter.class.getClassLoader());
+    private BakeTiming timing;
+    private boolean timingUnderWay;
+
+    BakeMeter() {
+        icon.setColorFilter(new FlatSVGIcon.ColorFilter(drawn -> color()));
+    }
+
+    void showTiming() {
+        timing = null;
+        timingUnderWay = true;
+        setToolTipText("Baking every variant five times over");
+        repaint();
+    }
+
+    void show(BakeTiming measured) {
+        timing = measured;
+        timingUnderWay = false;
+        setToolTipText(measured.explain());
+        repaint();
+    }
+
+    void clear() {
+        timing = null;
+        timingUnderWay = false;
+        setToolTipText(null);
+        repaint();
+    }
+
+    @Override
+    public Dimension getPreferredSize() {
+        return new Dimension(0, StudioTheme.scale(HEIGHT));
+    }
+
+    @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);
+            icon.paintIcon(this, canvas, 0, (getHeight() - icon.getIconHeight()) / 2);
+            int labelX = icon.getIconWidth() + StudioTheme.scale(GAP);
+            int barX = drawLabel(canvas, labelX) + StudioTheme.scale(GAP);
+            int timeX = getWidth() - timeWidth(canvas);
+            drawBar(canvas, barX, timeX - StudioTheme.scale(GAP) - barX);
+            drawTime(canvas, timeX);
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private Color color() {
+        return timing == null ? StudioTheme.MUTED_TEXT : weight().color();
+    }
+
+    private BakeWeight weight() {
+        return BakeWeight.of(timing.totalMillis());
+    }
+
+    // Returns where the label ends.
+    private int drawLabel(Graphics2D canvas, int x) {
+        canvas.setFont(StudioTheme.boldFont());
+        FontMetrics metrics = canvas.getFontMetrics();
+        canvas.setColor(color());
+        canvas.drawString(labelText(), x, baseline(metrics));
+        int widestLabelWidth = metrics.stringWidth(TIMING_LABEL);
+        for (BakeWeight each : BakeWeight.values()) {
+            widestLabelWidth = Math.max(widestLabelWidth, metrics.stringWidth(each.label()));
+        }
+        return x + widestLabelWidth;
+    }
+
+    private String labelText() {
+        if (timing != null) {
+            return weight().label();
+        }
+        return timingUnderWay ? TIMING_LABEL : "—";
+    }
+
+    private void drawBar(Graphics2D canvas, int x, int width) {
+        int barHeight = StudioTheme.scale(BAR_HEIGHT);
+        int y = (getHeight() - barHeight) / 2;
+        canvas.setColor(StudioTheme.HOVER_BACKGROUND);
+        canvas.fillRoundRect(x, y, width, barHeight, barHeight, barHeight);
+        if (timing == null) {
+            return;
+        }
+        int filledWidth = (int) Math.round(width * BakeWeight.meterFill(timing.totalMillis()));
+        canvas.setColor(color());
+        canvas.fillRoundRect(x, y, Math.max(barHeight, filledWidth), barHeight, barHeight, barHeight);
+    }
+
+    private int timeWidth(Graphics2D canvas) {
+        return canvas.getFontMetrics(StudioTheme.smallFont()).stringWidth(WIDEST_TIME);
+    }
+
+    private void drawTime(Graphics2D canvas, int x) {
+        if (timing == null) {
+            return;
+        }
+        canvas.setFont(StudioTheme.smallFont());
+        FontMetrics metrics = canvas.getFontMetrics();
+        String time = BakeTiming.formatMillis(timing.totalMillis());
+        canvas.setColor(StudioTheme.SECONDARY_TEXT);
+        canvas.drawString(time, x + timeWidth(canvas) - metrics.stringWidth(time), baseline(metrics));
+    }
+
+    private int baseline(FontMetrics metrics) {
+        return (getHeight() + metrics.getAscent() - metrics.getDescent()) / 2;
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/BakeRun.java

@@ -0,0 +1,25 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+/**
+ * How long one bake of a procedural object's variants took.
+ */
+record BakeRun(long totalNanos, int variantCount) {
+}

core/src/main/java/art/arcane/iris/studio/map/BakeTiming.java

@@ -0,0 +1,71 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Locale;
+import java.util.function.BooleanSupplier;
+import java.util.function.Supplier;
+
+/**
+ * A procedural object's variants baked five times over, keeping the median run. The first run is slow while the JIT
+ * compiles the baker, and the garbage collector or chunk generation can slow any other, so neither ends up in the middle.
+ */
+record BakeTiming(BakeRun median) {
+    private static final int RUN_COUNT = 5;
+    private static final double NANOS_PER_MILLI = 1_000_000D;
+
+    /** Null when {@code bake} finds nothing to bake, or once the timing is no longer wanted. */
+    static BakeTiming measure(Supplier<BakeRun> bake, BooleanSupplier stillWanted) {
+        List<BakeRun> runs = new ArrayList<>();
+        for (int run = 0; run < RUN_COUNT; run++) {
+            if (!stillWanted.getAsBoolean()) {
+                return null;
+            }
+            BakeRun measured = bake.get();
+            if (measured == null) {
+                return null;
+            }
+            runs.add(measured);
+        }
+        runs.sort(Comparator.comparingLong(BakeRun::totalNanos));
+        return new BakeTiming(runs.get(runs.size() / 2));
+    }
+
+    double totalMillis() {
+        return median.totalNanos() / NANOS_PER_MILLI;
+    }
+
+    /** How long the bake took and when world generation pays for it. */
+    String explain() {
+        String variants = median.variantCount() == 1 ? "1 variant" : median.variantCount() + " variants";
+        return "<html>" + variants + " in " + formatMillis(totalMillis()) + " · median of " + RUN_COUNT + " runs<br>"
+                + "Paid once per pack load, by the first chunk placing it<br>"
+                + BakeWeight.scale() + "</html>";
+    }
+
+    static String formatMillis(double millis) {
+        if (millis >= 1000D) {
+            return String.format(Locale.ROOT, "%.1f s", millis / 1000D);
+        }
+        return String.format(Locale.ROOT, millis < 10D ? "%.1f ms" : "%.0f ms", millis);
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/BakeWeight.java

@@ -0,0 +1,74 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.awt.Color;
+
+/**
+ * How long a procedural object's bake stalls the chunk that first places it, against a server tick of 50 ms.
+ */
+enum BakeWeight {
+    LIGHT("Light", 1D, 50D, StudioTheme.SUCCESS),
+    MODERATE("Moderate", 50D, 500D, StudioTheme.WARNING),
+    HEAVY("Heavy", 500D, 5_000D, StudioTheme.ERROR);
+
+    private final String label;
+    private final double fromMillis;
+    private final double meterFullAtMillis;
+    private final Color color;
+
+    BakeWeight(String label, double fromMillis, double meterFullAtMillis, Color color) {
+        this.label = label;
+        this.fromMillis = fromMillis;
+        this.meterFullAtMillis = meterFullAtMillis;
+        this.color = color;
+    }
+
+    static BakeWeight of(double millis) {
+        for (BakeWeight weight : values()) {
+            if (millis < weight.meterFullAtMillis) {
+                return weight;
+            }
+        }
+        return HEAVY;
+    }
+
+    /**
+     * How full the meter is for a bake of {@code millis}: each weight takes an equal share of the meter, filled on a
+     * logarithmic scale, since bakes span thousands of times.
+     */
+    static double meterFill(double millis) {
+        BakeWeight weight = of(millis);
+        double clamped = Math.clamp(millis, weight.fromMillis, weight.meterFullAtMillis);
+        double withinWeight = Math.log(clamped / weight.fromMillis) / Math.log(weight.meterFullAtMillis / weight.fromMillis);
+        return (weight.ordinal() + withinWeight) / values().length;
+    }
+
+    static String scale() {
+        return "Light under " + BakeTiming.formatMillis(MODERATE.fromMillis) + ", heavy from " + BakeTiming.formatMillis(HEAVY.fromMillis);
+    }
+
+    String label() {
+        return label;
+    }
+
+    Color color() {
+        return color;
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/BiomeExplorer.java

@@ -0,0 +1,177 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.PickMeasuring.TypedSpread;
+import art.arcane.iris.studio.map.components.PickDisplay;
+import art.arcane.iris.generation.runtime.IrisComplex;
+import art.arcane.iris.generation.runtime.Engine;
+import art.arcane.iris.generation.terrain.InferredType;
+import art.arcane.iris.generation.terrain.IrisRegion;
+import art.arcane.volmlib.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 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.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));
+        }
+        inspector.showRegionSections("Each region splits its own biome noise by rarity", sections);
+    }
+
+    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();
+        return new Measurement(regions);
+    }
+
+    /**
+     * 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 int count;
+
+        private RegionSamples(Engine engine, IrisComplex complex, IrisRegion region) {
+            this.complex = complex;
+            this.region = region;
+            this.spreads = PickMeasuring.biomeSpreads(engine, complex, region);
+        }
+
+        private void add(double x, double z) {
+            count++;
+            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<TypedSpread> inView = spreads.stream().filter(typed -> typed.spread().sampleCount() > 0).toList();
+            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());
+        }
+    }
+
+    private record RegionPicks(String key, String name, int color, double share, int biomeCount,
+                               List<NoisePickSpread> spreads) {
+    }
+
+    private record Measurement(List<RegionPicks> regions) {
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.generation.biome.IrisBiome;
+import art.arcane.iris.generation.biome.IrisBiomePaletteLayer;
+import art.arcane.iris.generation.block.IrisBlockData;
+import art.arcane.iris.generation.decoration.IrisDecorator;
+import art.arcane.volmlib.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/art/arcane/iris/studio/map/BiomePalettePlacement.java

@@ -0,0 +1,220 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.pack.loading.IrisData;
+import art.arcane.iris.generation.decoration.IrisDecorationPart;
+import art.arcane.iris.generation.decoration.IrisEngineDecorator;
+import art.arcane.iris.generation.runtime.Engine;
+import art.arcane.iris.generation.biome.IrisBiome;
+import art.arcane.iris.generation.biome.IrisBiomePaletteLayer;
+import art.arcane.iris.generation.block.IrisBlockData;
+import art.arcane.iris.generation.decoration.IrisDecorator;
+import art.arcane.iris.generation.terrain.IrisDimension;
+import art.arcane.volmlib.util.collection.KList;
+import art.arcane.volmlib.util.math.RNG;
+import art.arcane.volmlib.util.noise.CNG;
+
+/**
+ * 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, with 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());
+        int index = palette.index();
+        IrisBiomePaletteLayer layer = palette.layerIn(biome);
+        return switch (palette.kind()) {
+            case LAYER -> new StackedLayer(layer, index, biome.getLayerHeightGenerators(terrainRandom, data), terrainRandom, data);
+            case SEA_LAYER -> new StackedLayer(layer, index, biome.getLayerSeaHeightGenerators(terrainRandom, data), terrainRandom, data);
+            case CAVE_CEILING_LAYER -> new StackedLayer(layer, index, biome.getCaveCeilingLayerHeightGenerators(carveRandom, data),
+                    carveRandom, data);
+            case WALL -> new SingleBlocks(layer, data, carveRandom, seaLevel);
+            case SLAB -> new SingleBlocks(layer, data, postRandom, seaLevel);
+            case DECORATOR -> new Decorations(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;
+    }
+
+    /**
+     * 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);
+
+    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();
+        }
+    }
+
+    /**
+     * Surface, sea and cave ceiling layers. Each layer's thickness comes from its own noise in the list the generator
+     * builds, and every depth reseeds the block noise, sampled through the zoom twice.
+     */
+    private static final class StackedLayer extends LayerPlacement {
+        private final int index;
+        private final RNG random;
+        private final CNG thicknessNoise;
+
+        private StackedLayer(IrisBiomePaletteLayer layer, int index, KList<CNG> thicknessNoises, RNG random, IrisData data) {
+            super(layer, data);
+            this.index = index;
+            this.random = random;
+            this.thicknessNoise = index < thicknessNoises.size() ? thicknessNoises.get(index) : null;
+        }
+
+        @Override
+        int minThickness() {
+            return layer.getMinHeight();
+        }
+
+        @Override
+        int maxThickness() {
+            return layer.getMaxHeight();
+        }
+
+        @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, index + depth, data)
+                    .noise((blockX + depth) / zoom / zoom, depth / zoom, (blockZ - depth) / zoom / zoom);
+        }
+    }
+
+    /**
+     * 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 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);
+        }
+    }
+
+    /**
+     * A decorator places where its style noise stays under its chance, and its variance noise picks the block there.
+     * Surface and ceiling decorators pick single blocks from flat noise; sea and shore decorators pick from noise that
+     * also changes with height.
+     */
+    private static final class Decorations extends BiomePalettePlacement {
+        private final IrisDecorator decorator;
+        private final CNG placementNoise;
+        private final CNG blockNoise;
+        private final boolean picksFromFlatNoise;
+        private final int sampleHeight;
+
+        private Decorations(IrisDecorator decorator, long componentSeed, int sampleHeight, IrisData data) {
+            super(data);
+            this.decorator = decorator;
+            RNG partRandom = new RNG(IrisEngineDecorator.seedForPart(componentSeed, decorator.getPartOf()));
+            this.placementNoise = decorator.getGenerator(partRandom, data);
+            this.blockNoise = decorator.getVarianceGenerator(partRandom, data);
+            this.picksFromFlatNoise = decorator.getPartOf() == IrisDecorationPart.NONE
+                    || decorator.getPartOf() == IrisDecorationPart.CEILING;
+            this.sampleHeight = sampleHeight;
+        }
+
+        @Override
+        KList<IrisBlockData> blocks() {
+            return decorator.getPalette();
+        }
+
+        @Override
+        double zoom() {
+            return decorator.getStyle().getZoom();
+        }
+
+        @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 picksFromFlatNoise ? blockNoise.noiseFast2D(blockZ, blockX) : blockNoise.noise(blockZ, sampleHeight, blockX);
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/BiomeTint.java

@@ -0,0 +1,27 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+enum BiomeTint {
+    GRASS,
+    FOLIAGE,
+    DRY_FOLIAGE,
+    WATER
+}

core/src/main/java/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.generation.biome.IrisBiome;
+import art.arcane.iris.generation.biome.IrisBiomeCustom;
+import art.arcane.volmlib.util.collection.KList;
+import art.arcane.volmlib.util.math.RNG;
+
+import java.util.Locale;
+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.getSkyBiomeKey(biomeRandom, originX, 0, originZ));
+    }
+
+    // Follows the same choices as IrisBiome#getSkyBiomeKey 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<String> skyBiomes = biome.getBiomeSkyScatter();
+        if (!skyBiomes.isEmpty()) {
+            return skyBiomes.size() == 1 ? vanillaColors(skyBiomes.get(0)) : null;
+        }
+        KList<String> groundBiomes = biome.getBiomeScatter();
+        if (groundBiomes.isEmpty()) {
+            return vanillaColors(biome.getDerivativeKey());
+        }
+        return groundBiomes.size() == 1 ? vanillaColors(groundBiomes.get(0)) : null;
+    }
+
+    private BiomeTintColors customColors(IrisBiomeCustom customBiome) {
+        return colorsByCustomBiome.computeIfAbsent(customBiome, minecraftColors::custom);
+    }
+
+    private BiomeTintColors vanillaColors(String vanillaBiomeKey) {
+        return minecraftColors.vanilla(vanillaBiomeKey.trim().toLowerCase(Locale.ROOT));
+    }
+
+    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/art/arcane/iris/studio/map/BlockFaces.java

@@ -0,0 +1,320 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.Arrays;
+import java.util.function.IntUnaryOperator;
+
+/**
+ * The visible faces of noise terrain as columns, with neighbouring columns merged into one face where they show the
+ * same stretch: tops of one height along X, and sides of one height range along the side. A face runs {@code columns}
+ * columns from its first one and reaches {@code height} across: one column along Z for tops, blocks up for sides.
+ * <p>
+ * Hole walls follow the surface: a side from the floor up for each column next to where a {@link TerrainHole} may end,
+ * shown in place of the usual side while the column beside it is left out. No face crosses a hole's cell edge, so one
+ * set of faces serves every hole.
+ * <p>
+ * Faces depend on neither the camera nor the hole, so they are found once per terrain rather than every frame.
+ */
+final class BlockFaces {
+    private static final int INITIAL_CAPACITY = 1024;
+    private static final Facing[] FACINGS = Facing.values();
+    private static final Kind[] KINDS = Kind.values();
+
+    private final NoiseTerrain terrain;
+    private final int floorY;
+    // Faces are kept kind by kind, and facing by facing within a kind.
+    private final int[] firstOfGroup = new int[KINDS.length * FACINGS.length + 1];
+    private int count;
+    private int[] firstColumn = new int[INITIAL_CAPACITY];
+    private int[] firstRow = new int[INITIAL_CAPACITY];
+    private int[] bottomY = new int[INITIAL_CAPACITY];
+    private int[] columns = new int[INITIAL_CAPACITY];
+    private int[] height = new int[INITIAL_CAPACITY];
+    private byte[] facing = new byte[INITIAL_CAPACITY];
+
+    private BlockFaces(NoiseTerrain terrain, int floorY) {
+        this.terrain = terrain;
+        this.floorY = floorY;
+    }
+
+    /**
+     * @param floorY where sides on the edge, next to a gap or into a hole end
+     */
+    static BlockFaces of(NoiseTerrain terrain, int floorY) {
+        BlockFaces faces = new BlockFaces(terrain, floorY);
+        for (Kind kind : KINDS) {
+            for (Facing facing : FACINGS) {
+                faces.firstOfGroup[group(kind, facing)] = faces.count;
+                faces.add(kind, facing);
+            }
+        }
+        faces.firstOfGroup[KINDS.length * FACINGS.length] = faces.count;
+        faces.trimToCount();
+        return faces;
+    }
+
+    private static int group(Kind kind, Facing facing) {
+        return kind.ordinal() * FACINGS.length + facing.ordinal();
+    }
+
+    private void add(Kind kind, Facing facing) {
+        if (kind == Kind.HOLE_WALL) {
+            addHoleWalls(facing);
+        } else if (facing == Facing.TOP) {
+            addTops();
+        } else {
+            addSides(facing);
+        }
+    }
+
+    // A height of 64 places blocks up to y 64, so the column's top face is at 65.
+    static int blockTop(double height) {
+        return (int) Math.floor(height) + 1;
+    }
+
+    int count() {
+        return count;
+    }
+
+    // All faces of one kind and facing follow on from the first.
+    int first(Kind kind, Facing facing) {
+        return firstOfGroup[group(kind, facing)];
+    }
+
+    int count(Kind kind, Facing facing) {
+        return firstOfGroup[group(kind, facing) + 1] - firstOfGroup[group(kind, facing)];
+    }
+
+    boolean isHoleWall(int face) {
+        return face >= first(Kind.HOLE_WALL, FACINGS[0]);
+    }
+
+    int bottomY(int face) {
+        return bottomY[face];
+    }
+
+    Facing facing(int face) {
+        return FACINGS[facing[face]];
+    }
+
+    int columns(int face) {
+        return columns[face];
+    }
+
+    int height(int face) {
+        return height[face];
+    }
+
+    // The column and row of the face's first column; the others follow along its run.
+    int firstColumn(int face) {
+        return firstColumn[face];
+    }
+
+    int firstRow(int face) {
+        return firstRow[face];
+    }
+
+    // The corner the face runs and reaches from; east and south sides lie on the far edge of their column.
+    double originX(int face) {
+        return terrain.worldX(firstColumn[face] + (facing(face).normalX > 0 ? 1 : 0));
+    }
+
+    double originY(int face) {
+        return bottomY[face];
+    }
+
+    double originZ(int face) {
+        return terrain.worldZ(firstRow[face] + (facing(face).normalZ > 0 ? 1 : 0));
+    }
+
+    double runX(int face) {
+        return facing(face).runsAlongX() ? (double) columns[face] * terrain.step() : 0D;
+    }
+
+    double runZ(int face) {
+        return facing(face).runsAlongX() ? 0D : (double) columns[face] * terrain.step();
+    }
+
+    double reachY(int face) {
+        return facing(face) == Facing.TOP ? 0D : height[face];
+    }
+
+    double reachZ(int face) {
+        return facing(face) == Facing.TOP ? (double) height[face] * terrain.step() : 0D;
+    }
+
+    private boolean hasColumn(int column, int row) {
+        return terrain.hasHeight(column, row);
+    }
+
+    private static boolean startsCell(int columnOrRow) {
+        return columnOrRow % TerrainHole.CELL_COLUMNS == 0;
+    }
+
+    private void addTops() {
+        for (int row = 0; row < terrain.rows(); row++) {
+            int column = 0;
+            while (column < terrain.columns()) {
+                if (!hasColumn(column, row)) {
+                    column++;
+                    continue;
+                }
+                int top = blockTop(terrain.height(column, row));
+                int runEnd = column + 1;
+                while (runEnd < terrain.columns() && !startsCell(runEnd) && hasColumn(runEnd, row)
+                        && blockTop(terrain.height(runEnd, row)) == top) {
+                    runEnd++;
+                }
+                add(Facing.TOP, column, row, top, runEnd - column, 1);
+                column = runEnd;
+            }
+        }
+    }
+
+    private void addSides(Facing side) {
+        for (int lane = 0; lane < lanes(side); lane++) {
+            int sideLane = lane;
+            addSideRuns(side, lane, step -> sideBottom(side, sideLane, step));
+        }
+    }
+
+    // A hole only ends on the lines between cells, so walls only stand along those inside the terrain.
+    private void addHoleWalls(Facing side) {
+        if (side == Facing.TOP) {
+            return;
+        }
+        int towardNeighbour = side.runsAlongX() ? side.normalZ : side.normalX;
+        for (int lane = 0; lane < lanes(side); lane++) {
+            int neighbourLane = lane + towardNeighbour;
+            boolean facesNextCell = lane / TerrainHole.CELL_COLUMNS != neighbourLane / TerrainHole.CELL_COLUMNS;
+            if (neighbourLane >= 0 && neighbourLane < lanes(side) && facesNextCell) {
+                addSideRuns(side, lane, step -> floorY);
+            }
+        }
+    }
+
+    private int lanes(Facing side) {
+        return side.runsAlongX() ? terrain.rows() : terrain.columns();
+    }
+
+    private void addSideRuns(Facing side, int lane, IntUnaryOperator bottomAt) {
+        int steps = side.runsAlongX() ? terrain.columns() : terrain.rows();
+        int step = 0;
+        while (step < steps) {
+            int top = sideTop(side, lane, step);
+            int bottom = bottomAt.applyAsInt(step);
+            if (bottom >= top) {
+                step++;
+                continue;
+            }
+            int runEnd = step + 1;
+            while (runEnd < steps && !startsCell(runEnd) && sideTop(side, lane, runEnd) == top && bottomAt.applyAsInt(runEnd) == bottom) {
+                runEnd++;
+            }
+            add(side, side.column(lane, step), side.row(lane, step), bottom, runEnd - step, top - bottom);
+            step = runEnd;
+        }
+    }
+
+    // No column means no side, which the caller sees as a side with no height.
+    private int sideTop(Facing side, int lane, int step) {
+        int column = side.column(lane, step);
+        int row = side.row(lane, step);
+        return hasColumn(column, row) ? blockTop(terrain.height(column, row)) : Integer.MIN_VALUE;
+    }
+
+    // Columns on the edge, or next to a gap, show their side all the way down to the floor.
+    private int sideBottom(Facing side, int lane, int step) {
+        int column = side.column(lane, step) + side.normalX;
+        int row = side.row(lane, step) + side.normalZ;
+        return hasColumn(column, row) ? blockTop(terrain.height(column, row)) : floorY;
+    }
+
+    private void add(Facing faceFacing, int column, int row, int bottom, int runColumns, int reach) {
+        if (count == facing.length) {
+            grow();
+        }
+        firstColumn[count] = column;
+        firstRow[count] = row;
+        bottomY[count] = bottom;
+        columns[count] = runColumns;
+        height[count] = reach;
+        facing[count] = (byte) faceFacing.ordinal();
+        count++;
+    }
+
+    private void grow() {
+        resizeTo(facing.length * 2);
+    }
+
+    // Large terrain keeps millions of faces, so the room left over from growing would be a lot of memory.
+    private void trimToCount() {
+        resizeTo(count);
+    }
+
+    private void resizeTo(int capacity) {
+        firstColumn = Arrays.copyOf(firstColumn, capacity);
+        firstRow = Arrays.copyOf(firstRow, capacity);
+        bottomY = Arrays.copyOf(bottomY, capacity);
+        columns = Arrays.copyOf(columns, capacity);
+        height = Arrays.copyOf(height, capacity);
+        facing = Arrays.copyOf(facing, capacity);
+    }
+
+    /**
+     * Which way a face looks. Tops and north and south sides run along X; east and west sides run along Z.
+     */
+    enum Facing {
+        TOP(0, 1, 0),
+        NORTH(0, 0, -1),
+        SOUTH(0, 0, 1),
+        WEST(-1, 0, 0),
+        EAST(1, 0, 0);
+
+        final int normalX;
+        final int normalY;
+        final int normalZ;
+
+        Facing(int normalX, int normalY, int normalZ) {
+            this.normalX = normalX;
+            this.normalY = normalY;
+            this.normalZ = normalZ;
+        }
+
+        boolean runsAlongX() {
+            return normalX == 0;
+        }
+
+        // A lane is a row for faces running along X and a column for the others; steps go along the lane.
+        int column(int lane, int step) {
+            return runsAlongX() ? step : lane;
+        }
+
+        int row(int lane, int step) {
+            return runsAlongX() ? lane : step;
+        }
+    }
+
+    // Surface faces show unless their column is in a hole; hole walls only beside one.
+    enum Kind {
+        SURFACE,
+        HOLE_WALL
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/BlockHeightColorScale.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 art.arcane.iris.studio.map;
+
+import java.awt.Color;
+
+/**
+ * Colours noise that is already a height in blocks, spreading a palette over the heights it can reach.
+ */
+record BlockHeightColorScale(NoisePalette palette, double minimum, double maximum) implements NoiseColorScale {
+    @Override
+    public int colorFinite(double value) {
+        double span = maximum - minimum;
+        return palette.colorNormalized(span <= 0D ? 0.5D : (value - minimum) / span);
+    }
+
+    @Override
+    public int colorInvalid() {
+        return palette.colorInvalid();
+    }
+
+    @Override
+    public Color displayColorNormalized(double normalized) {
+        return palette.displayColorNormalized(normalized);
+    }
+
+    @Override
+    public String label() {
+        return "Blocks";
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import art.arcane.iris.studio.map.BlockModel.BoxCorners;
+import art.arcane.iris.studio.map.BlockModel.Face;
+import art.arcane.iris.studio.map.BlockModel.TextureMapping;
+import art.arcane.iris.studio.map.BlockTextures.BlockStateId;
+import art.arcane.iris.studio.map.BlockTextures.BlockTexture;
+import art.arcane.iris.studio.map.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/art/arcane/iris/studio/map/BlockNames.java

@@ -0,0 +1,35 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.generation.decoration.IrisProceduralBlocks;
+import art.arcane.volmlib.nativelib.terrain.NativeBlockState;
+
+final class BlockNames {
+    private BlockNames() {
+    }
+
+    /**
+     * @return the block's type without namespace or properties, like {@code oak_log}
+     */
+    static String typeOf(NativeBlockState block) {
+        String material = IrisProceduralBlocks.materialKey(block);
+        return material.substring(material.indexOf(':') + 1);
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/BlockPreviewColors.java

@@ -0,0 +1,74 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.volmlib.nativelib.terrain.NativeBlockState;
+
+import java.awt.Color;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+// Colours for blocks without a texture, such as when the client jar can't be read.
+final class BlockPreviewColors {
+    private static final double[] MAP_SHADES = {1D, 0.86D, 0.71D, 0.53D};
+
+    private BlockPreviewColors() {
+    }
+
+    static Map<String, Integer> colorsByBlock(List<NativeBlockState> blocks) {
+        Map<String, Integer> colors = new HashMap<>();
+        List<Integer> usedColors = new ArrayList<>();
+        for (NativeBlockState block : blocks) {
+            String key = block.key();
+            if (colors.containsKey(key)) {
+                continue;
+            }
+            int baseColor = colorFromName(BlockNames.typeOf(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 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;
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/BlockTextures.java

@@ -0,0 +1,623 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import art.arcane.iris.generation.decoration.IrisProceduralBlocks;
+import art.arcane.volmlib.nativelib.terrain.NativeBlockState;
+
+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(NativeBlockState 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(NativeBlockState block) {
+        return resolve(withHalf(block, BlockHalf.LOWER).orElse(block)).map(ResolvedTexture::texture);
+    }
+
+    /**
+     * The sprite of a two block tall plant's top half, or nothing for any other block.
+     */
+    Optional<BlockTexture> upperHalfIcon(NativeBlockState block) {
+        return withHalf(block, BlockHalf.UPPER).flatMap(this::resolve)
+                .filter(ResolvedTexture::isSideOnSprite).map(ResolvedTexture::texture);
+    }
+
+    /**
+     * What the block looks like from every side, for drawing it in 3D.
+     */
+    Optional<BlockModel> model(NativeBlockState block) {
+        return resolvedModels.computeIfAbsent(block.key(), modelBuilder::build);
+    }
+
+    private static Optional<NativeBlockState> withHalf(NativeBlockState block, BlockHalf half) {
+        String current = IrisProceduralBlocks.propertyValue(block, BlockHalf.PROPERTY);
+        if (current == null) {
+            return Optional.empty();
+        }
+        return Optional.of(block.withProperty(BlockHalf.PROPERTY, half.valueLike(current)));
+    }
+
+    // Blockstate files match on every property, so defaults the pack left out have to be spelled out too.
+    private Optional<ResolvedTexture> resolve(NativeBlockState block) {
+        return resolvedTextures.computeIfAbsent(block.key(), this::resolveTopTexture);
+    }
+
+    // Two block tall blocks call their halves lower and upper; stairs and trapdoors call them bottom and top.
+    private enum BlockHalf {
+        LOWER("lower", "bottom"),
+        UPPER("upper", "top");
+
+        static final String PROPERTY = "half";
+
+        private final String tallBlockValue;
+        private final String slabLikeValue;
+
+        BlockHalf(String tallBlockValue, String slabLikeValue) {
+            this.tallBlockValue = tallBlockValue;
+            this.slabLikeValue = slabLikeValue;
+        }
+
+        String valueLike(String currentValue) {
+            boolean isTallBlock = currentValue.equals(LOWER.tallBlockValue) || currentValue.equals(UPPER.tallBlockValue);
+            return isTallBlock ? tallBlockValue : slabLikeValue;
+        }
+    }
+
+    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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/ColumnArea.java

@@ -0,0 +1,25 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+/**
+ * A rectangle of a terrain's columns and rows, from the first up to but not including the last.
+ */
+record ColumnArea(int fromColumn, int fromRow, int toColumn, int toRow) {
+}

core/src/main/java/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+/**
+ * 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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.BlockModel.Face;
+import art.arcane.iris.studio.map.BlockModel.TextureMapping;
+import art.arcane.iris.studio.map.BlockTextures.BlockStateId;
+import art.arcane.iris.studio.map.BlockTextures.BlockTexture;
+import art.arcane.iris.studio.map.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/art/arcane/iris/studio/map/FloatingPanels.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 art.arcane.iris.studio.map;
+
+import javax.swing.SwingUtilities;
+import java.awt.Component;
+import java.awt.Container;
+import java.awt.Rectangle;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Finds the Swing panels floating over a native window, the way AWT does when it cuts them out of that window. Only
+ * for the Swing thread.
+ */
+final class FloatingPanels {
+    private FloatingPanels() {
+    }
+
+    /**
+     * A floating panel that hides what lies behind most of it, and only lets it show through some parts.
+     */
+    interface PartlySeeThrough {
+        /**
+         * @return where what lies behind shows through, in the panel's own coordinates
+         */
+        List<Rectangle> seeThroughParts();
+    }
+
+    /**
+     * @return where what the window shows has to show through the panels over it, in the window's coordinates
+     */
+    static List<Rectangle> seeThroughOver(Component window) {
+        List<Rectangle> parts = new ArrayList<>();
+        Rectangle windowBounds = new Rectangle(0, 0, window.getWidth(), window.getHeight());
+        Component child = window;
+        Container parent = child.getParent();
+        while (parent != null) {
+            for (int index = parent.getComponentZOrder(child) - 1; index >= 0; index--) {
+                Component above = parent.getComponent(index);
+                if (above.isLightweight() && above.isShowing()) {
+                    addSeeThroughParts(above, window, windowBounds, parts);
+                }
+            }
+            if (!parent.isLightweight()) {
+                break;
+            }
+            child = parent;
+            parent = parent.getParent();
+        }
+        return parts;
+    }
+
+    private static void addSeeThroughParts(Component panel, Component window, Rectangle windowBounds, List<Rectangle> parts) {
+        List<Rectangle> panelParts = panel instanceof PartlySeeThrough partly
+                ? partly.seeThroughParts()
+                : List.of(new Rectangle(0, 0, panel.getWidth(), panel.getHeight()));
+        for (Rectangle part : panelParts) {
+            Rectangle inWindow = SwingUtilities.convertRectangle(panel, part, window).intersection(windowBounds);
+            if (!inWindow.isEmpty()) {
+                parts.add(inWindow);
+            }
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/FloatingSlider.java

@@ -0,0 +1,175 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+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 vertical slider floating over the right edge of a 3D view, halfway down, with a short label above it. It
+ * stays faint so it hides little of the view, until the mouse comes near or it is told to stand out.
+ */
+final class FloatingSlider 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 static final String BLANK_LABEL = " ";
+
+    private final JSlider slider = new JSlider(SwingConstants.VERTICAL, 0, 1, 1);
+    private final JLabel label = new JLabel(BLANK_LABEL, SwingConstants.CENTER);
+    private boolean movingQuietly;
+    private boolean hovered;
+    private boolean standingOut;
+
+    /**
+     * @param onMoved told the slider's value whenever the user moves it
+     */
+    FloatingSlider(String tooltip, IntConsumer onMoved) {
+        super(new BorderLayout(0, StudioTheme.scale(4)));
+        setOpaque(false);
+        setToolTipText(tooltip);
+        label.setFont(StudioTheme.smallFont());
+        label.setForeground(StudioTheme.SECONDARY_TEXT);
+        slider.setOpaque(false);
+        slider.setFocusable(false);
+        slider.setToolTipText(tooltip);
+        slider.addChangeListener(event -> {
+            if (!movingQuietly) {
+                onMoved.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(label, BorderLayout.NORTH);
+        add(slider, BorderLayout.CENTER);
+    }
+
+    /**
+     * The view with this slider floating over its right edge, halfway down.
+     */
+    JComponent floatingOver(JComponent view) {
+        FloatingSlider floating = 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));
+                floating.setBounds(getWidth() - width - StudioTheme.scale(EDGE_MARGIN), (getHeight() - height) / 2, width, height);
+            }
+        };
+        stack.add(floating);
+        stack.add(view);
+        return stack;
+    }
+
+    /**
+     * Shows a range and value the user didn't choose, without telling anyone the slider moved.
+     */
+    void showQuietly(int minimum, int maximum, int value) {
+        movingQuietly = true;
+        try {
+            slider.getModel().setRangeProperties(value, 0, minimum, maximum, false);
+        } finally {
+            movingQuietly = false;
+        }
+    }
+
+    // Moves the slider as if the user had.
+    void moveBy(int steps) {
+        slider.setValue(slider.getValue() + steps);
+    }
+
+    int value() {
+        return slider.getValue();
+    }
+
+    int maximum() {
+        return slider.getMaximum();
+    }
+
+    void showLabel(String text) {
+        label.setText(text.isEmpty() ? BLANK_LABEL : text);
+        repaint();
+    }
+
+    void setStandingOut(boolean nowStandingOut) {
+        if (standingOut != nowStandingOut) {
+            standingOut = nowStandingOut;
+            repaint();
+        }
+    }
+
+    @Override
+    protected void paintChildren(Graphics graphics) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            if (!hovered && !standingOut) {
+                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();
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/FrameRateLabel.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 art.arcane.iris.studio.map;
+
+import javax.swing.JComponent;
+import java.awt.Dimension;
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+
+/**
+ * How many frames a second a 3D view keeps up, right-aligned, floating over the view.
+ */
+final class FrameRateLabel extends JComponent {
+    private static final long serialVersionUID = -6402187316475095871L;
+    private static final String WIDEST_TEXT = "8888 fps";
+
+    private String text = "";
+
+    FrameRateLabel() {
+        setOpaque(false);
+    }
+
+    void showRate(double framesPerSecond) {
+        String next = Math.round(framesPerSecond) + " fps";
+        if (!next.equals(text)) {
+            text = next;
+            repaint();
+        }
+    }
+
+    @Override
+    public Dimension getPreferredSize() {
+        FontMetrics metrics = getFontMetrics(StudioTheme.smallFont());
+        return new Dimension(metrics.stringWidth(WIDEST_TEXT), metrics.getHeight());
+    }
+
+    @Override
+    protected void paintComponent(Graphics graphics) {
+        Graphics2D canvas = (Graphics2D) graphics;
+        canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+        canvas.setFont(StudioTheme.smallFont());
+        canvas.setColor(StudioTheme.MUTED_TEXT);
+        FontMetrics metrics = canvas.getFontMetrics();
+        canvas.drawString(text, getWidth() - metrics.stringWidth(text), metrics.getAscent());
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GlxDisplay.java

@@ -0,0 +1,366 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.spi.IrisLogging;
+import org.lwjgl.PointerBuffer;
+import org.lwjgl.opengl.GL;
+import org.lwjgl.opengl.GLXCapabilities;
+import org.lwjgl.system.Callback;
+import org.lwjgl.system.CallbackI;
+import org.lwjgl.system.Configuration;
+import org.lwjgl.system.JNI;
+import org.lwjgl.system.MemoryStack;
+import org.lwjgl.system.linux.DynamicLinkLoader;
+import org.lwjgl.system.linux.X11;
+import org.lwjgl.system.linux.XErrorEvent;
+
+import java.awt.GraphicsEnvironment;
+import java.awt.Toolkit;
+import java.lang.invoke.MethodHandles;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashSet;
+import java.util.Locale;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+import static org.lwjgl.opengl.GL11.GL_RENDERER;
+import static org.lwjgl.opengl.GL11.glGetString;
+import static org.lwjgl.opengl.GLX.glXDestroyContext;
+import static org.lwjgl.opengl.GLX.glXMakeCurrent;
+import static org.lwjgl.opengl.GLX.glXSwapBuffers;
+import static org.lwjgl.opengl.GLX13.*;
+import static org.lwjgl.opengl.GLXARBCreateContext.*;
+import static org.lwjgl.opengl.GLXARBCreateContextProfile.GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
+import static org.lwjgl.opengl.GLXARBCreateContextProfile.GLX_CONTEXT_PROFILE_MASK_ARB;
+import static org.lwjgl.opengl.GLXEXTSwapControl.glXSwapIntervalEXT;
+import static org.lwjgl.system.APIUtil.apiClosureRet;
+import static org.lwjgl.system.APIUtil.apiCreateCIF;
+import static org.lwjgl.system.MemoryUtil.NULL;
+import static org.lwjgl.system.MemoryUtil.memAddress;
+import static org.lwjgl.system.MemoryUtil.memGetAddress;
+import static org.lwjgl.system.libffi.LibFFI.ffi_type_pointer;
+import static org.lwjgl.system.libffi.LibFFI.ffi_type_sint32;
+
+/**
+ * A connection of our own to the X server Swing's windows are on, with one OpenGL context that draws straight into
+ * those windows, so a frame never has to be copied back and painted by Swing. Only for the GPU thread.
+ */
+final class GlxDisplay {
+    private static final String X11_TOOLKIT = "sun.awt.X11.XToolkit";
+    private static final String NATIVE_CONTEXT_API = "native";
+    private static final String NVIDIA_DRIVER_VERSION_FILE = "/proc/driver/nvidia/version";
+    private static final Set<String> SOFTWARE_RENDERERS = Set.of("llvmpipe", "softpipe", "software rasterizer");
+    private static final int OPENGL_MAJOR_VERSION = 3;
+    private static final int OPENGL_MINOR_VERSION = 3;
+    private static final int COLOR_CHANNEL_BITS = 8;
+    private static final int DEPTH_BITS = 24;
+    // Frames are only drawn when something moves, and the compositor keeps them from tearing.
+    private static final int SWAP_EVERY_FRAME = 0;
+
+    private final long display;
+    private final long context;
+    private final long visualId;
+    private final boolean canSetSwapInterval;
+    private final Set<Long> windowsWithSwapIntervalSet = new HashSet<>();
+    private final String renderer;
+    private long currentWindow;
+
+    private GlxDisplay(long display, long context, long visualId, boolean canSetSwapInterval, String renderer) {
+        this.display = display;
+        this.context = context;
+        this.visualId = visualId;
+        this.canSetSwapInterval = canSetSwapInterval;
+        this.renderer = renderer;
+    }
+
+    /**
+     * Opens the connection and makes its context current on this thread, without any window yet.
+     *
+     * @throws IllegalStateException when Swing doesn't draw on X or no card there draws OpenGL 3.3 in hardware
+     */
+    static GlxDisplay open() {
+        if (!isSwingOnX()) {
+            throw new IllegalStateException("Swing doesn't draw on X");
+        }
+        preferNvidiaCard();
+        // LWJGL would take EGL in a Wayland session, even though Swing's windows are on X.
+        Configuration.OPENGL_CONTEXT_API.set(NATIVE_CONTEXT_API);
+        GL.create();
+        long display = X11.nXOpenDisplay(NULL);
+        if (display == NULL) {
+            GL.destroy();
+            throw new IllegalStateException("Can't connect to the X server");
+        }
+        XErrors.watch(display);
+        try {
+            return openOn(display);
+        } catch (RuntimeException failure) {
+            XErrors.forget(display);
+            X11.XCloseDisplay(display);
+            GL.destroy();
+            throw failure;
+        }
+    }
+
+    static boolean isSwingOnX() {
+        return !GraphicsEnvironment.isHeadless() && X11_TOOLKIT.equals(Toolkit.getDefaultToolkit().getClass().getName());
+    }
+
+    private static GlxDisplay openOn(long display) {
+        int screen = X11.XDefaultScreen(display);
+        GLXCapabilities glx = GL.createCapabilitiesGLX(display, screen);
+        if (!glx.GLX13 || !glx.GLX_ARB_create_context || !glx.GLX_ARB_create_context_profile) {
+            throw new IllegalStateException("GLX can't make an OpenGL " + OPENGL_MAJOR_VERSION + "." + OPENGL_MINOR_VERSION + " context");
+        }
+        long visualId = Xlib.defaultVisualId(display, screen);
+        long config = configFor(display, screen, visualId);
+        long context = glXCreateContextAttribsARB(display, config, NULL, true, new int[]{
+                GLX_CONTEXT_MAJOR_VERSION_ARB, OPENGL_MAJOR_VERSION,
+                GLX_CONTEXT_MINOR_VERSION_ARB, OPENGL_MINOR_VERSION,
+                GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_CORE_PROFILE_BIT_ARB,
+                0});
+        Xlib.sync(display);
+        if (context == NULL || XErrors.takeFailed(display)) {
+            throw new IllegalStateException("GLX can't make an OpenGL " + OPENGL_MAJOR_VERSION + "." + OPENGL_MINOR_VERSION + " context");
+        }
+        if (!glXMakeContextCurrent(display, NULL, NULL, context)) {
+            glXDestroyContext(display, context);
+            throw new IllegalStateException("GLX can't use a context without a window");
+        }
+        GL.createCapabilities();
+        String renderer = glGetString(GL_RENDERER);
+        if (isDrawnInSoftware(renderer)) {
+            glXMakeContextCurrent(display, NULL, NULL, NULL);
+            glXDestroyContext(display, context);
+            throw new IllegalStateException("GLX only draws in software, on " + renderer);
+        }
+        return new GlxDisplay(display, context, visualId, glx.GLX_EXT_swap_control, renderer);
+    }
+
+    /**
+     * Laptops show X on the built-in card and only lend the faster one out when asked to. Asked the way NVIDIA's own
+     * prime-run does, unless whoever started the server asked for something else already.
+     */
+    private static void preferNvidiaCard() {
+        if (!Files.exists(Path.of(NVIDIA_DRIVER_VERSION_FILE))) {
+            return;
+        }
+        LibC.setenvUnlessSet("__NV_PRIME_RENDER_OFFLOAD", "1");
+        LibC.setenvUnlessSet("__GLX_VENDOR_LIBRARY_NAME", "nvidia");
+    }
+
+    // Windows are only drawn into with the visual they were made with; Swing makes them with the screen's default one.
+    private static long configFor(long display, int screen, long visualId) {
+        PointerBuffer configs = glXChooseFBConfig(display, screen, new int[]{
+                GLX_X_RENDERABLE, 1,
+                GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
+                GLX_RENDER_TYPE, GLX_RGBA_BIT,
+                GLX_DOUBLEBUFFER, 1,
+                GLX_RED_SIZE, COLOR_CHANNEL_BITS,
+                GLX_GREEN_SIZE, COLOR_CHANNEL_BITS,
+                GLX_BLUE_SIZE, COLOR_CHANNEL_BITS,
+                GLX_DEPTH_SIZE, DEPTH_BITS,
+                0});
+        if (configs == null) {
+            throw new IllegalStateException("GLX has no double-buffered config with a depth buffer");
+        }
+        try {
+            int[] configVisual = new int[1];
+            for (int index = 0; index < configs.remaining(); index++) {
+                long config = configs.get(index);
+                glXGetFBConfigAttrib(display, config, GLX_VISUAL_ID, configVisual);
+                if (configVisual[0] == visualId) {
+                    return config;
+                }
+            }
+        } finally {
+            X11.XFree(configs);
+        }
+        throw new IllegalStateException("GLX can't draw into windows of the default visual 0x" + Long.toHexString(visualId));
+    }
+
+    private static boolean isDrawnInSoftware(String renderer) {
+        String lowerCase = renderer == null ? "" : renderer.toLowerCase(Locale.ROOT);
+        return SOFTWARE_RENDERERS.stream().anyMatch(lowerCase::contains);
+    }
+
+    String renderer() {
+        return renderer;
+    }
+
+    boolean canDrawInto(long windowVisualId) {
+        return windowVisualId == visualId;
+    }
+
+    /**
+     * Makes the window what the default framebuffer draws into.
+     *
+     * @return false when the window can't be drawn into
+     */
+    boolean drawInto(long window) {
+        if (window == currentWindow) {
+            return true;
+        }
+        boolean madeCurrent = glXMakeCurrent(display, window, context);
+        Xlib.sync(display);
+        if (!madeCurrent || XErrors.takeFailed(display)) {
+            currentWindow = NULL;
+            return false;
+        }
+        currentWindow = window;
+        if (canSetSwapInterval && windowsWithSwapIntervalSet.add(window)) {
+            glXSwapIntervalEXT(display, window, SWAP_EVERY_FRAME);
+        }
+        return true;
+    }
+
+    /**
+     * Puts what was drawn into the window on screen.
+     *
+     * @return false when the window couldn't take it, or something drawn into it before failed
+     */
+    boolean show(long window) {
+        glXSwapBuffers(display, window);
+        return !XErrors.takeFailed(display);
+    }
+
+    /**
+     * Stops drawing into a window before it goes away, keeping the context for the rest.
+     */
+    void forget(long window) {
+        windowsWithSwapIntervalSet.remove(window);
+        if (window != currentWindow) {
+            return;
+        }
+        glXMakeContextCurrent(display, NULL, NULL, context);
+        currentWindow = NULL;
+        Xlib.sync(display);
+        XErrors.takeFailed(display);
+    }
+
+    /**
+     * Destroys the context and the connection. Nothing is drawn through this display afterwards.
+     */
+    void close() {
+        glXMakeContextCurrent(display, NULL, NULL, NULL);
+        glXDestroyContext(display, context);
+        currentWindow = NULL;
+        windowsWithSwapIntervalSet.clear();
+        Xlib.sync(display);
+        XErrors.forget(display);
+        X11.XCloseDisplay(display);
+    }
+
+    /**
+     * Notes X errors on our own connection instead of letting Xlib end the process over them, which is what it does
+     * for any connection but Swing's. Errors on other connections go wherever they went before.
+     */
+    private static final class XErrors {
+        private static final Set<Long> watchedDisplays = ConcurrentHashMap.newKeySet();
+        private static final Set<Long> failedDisplays = ConcurrentHashMap.newKeySet();
+        private static long previousHandler;
+        private static ErrorHandler handler;
+
+        static synchronized void watch(long display) {
+            if (handler == null) {
+                handler = XErrors::handle;
+                previousHandler = Xlib.setErrorHandler(handler.address());
+            }
+            watchedDisplays.add(display);
+        }
+
+        static void forget(long display) {
+            watchedDisplays.remove(display);
+            failedDisplays.remove(display);
+        }
+
+        static boolean takeFailed(long display) {
+            return failedDisplays.remove(display);
+        }
+
+        private static int handle(long display, long errorEvent) {
+            if (watchedDisplays.contains(display)) {
+                failedDisplays.add(display);
+                IrisLogging.debug("X error " + Byte.toUnsignedInt(XErrorEvent.create(errorEvent).error_code()) + " drawing a 3D view");
+                return 0;
+            }
+            return previousHandler == NULL ? 0 : JNI.callPPI(display, errorEvent, previousHandler);
+        }
+    }
+
+    @FunctionalInterface
+    private interface ErrorHandler extends CallbackI {
+        Callback.Descriptor DESCRIPTOR = new Callback.Descriptor(ErrorHandler.class, MethodHandles.lookup(),
+                apiCreateCIF(ffi_type_sint32, ffi_type_pointer, ffi_type_pointer));
+
+        @Override
+        default Callback.Descriptor getDescriptor() {
+            return DESCRIPTOR;
+        }
+
+        @Override
+        default void callback(long ret, long args) {
+            apiClosureRet(ret, invoke(memGetAddress(memGetAddress(args)), memGetAddress(memGetAddress(args + Long.BYTES))));
+        }
+
+        int invoke(long display, long errorEvent);
+    }
+
+    // The few Xlib calls LWJGL has no binding for.
+    private static final class Xlib {
+        static long defaultVisualId(long display, int screen) {
+            long visual = JNI.callPP(display, screen, function("XDefaultVisual"));
+            return JNI.callPP(visual, function("XVisualIDFromVisual"));
+        }
+
+        static void sync(long display) {
+            JNI.callPI(display, 0, function("XSync"));
+        }
+
+        static long setErrorHandler(long handler) {
+            return JNI.callPP(handler, function("XSetErrorHandler"));
+        }
+
+        private static long function(String name) {
+            long address = X11.getLibrary().getFunctionAddress(name);
+            if (address == NULL) {
+                throw new IllegalStateException("Xlib has no " + name);
+            }
+            return address;
+        }
+    }
+
+    private static final class LibC {
+        private static final int KEEP_EXISTING = 0;
+        private static final long EVERYTHING_LOADED = NULL;
+
+        // Looked up among everything the process loaded, which LWJGL's own dlsym won't do.
+        static void setenvUnlessSet(String name, String value) {
+            try (MemoryStack stack = MemoryStack.stackPush()) {
+                long setenv = DynamicLinkLoader.ndlsym(EVERYTHING_LOADED, memAddress(stack.ASCII("setenv")));
+                if (setenv == NULL) {
+                    return;
+                }
+                JNI.callPPI(memAddress(stack.ASCII(name)), memAddress(stack.ASCII(value)), KEEP_EXISTING, setenv);
+            }
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuCache.java

@@ -0,0 +1,106 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * What was put on the graphics card, by what it was made from. The sources are held weakly: once nothing else keeps
+ * one, its upload can never be asked for again and is deleted. Only for the GPU thread.
+ */
+final class GpuCache<U extends GpuCache.Upload> {
+    private final LinkedHashMap<Source, U> leastRecentlyUsedFirst = new LinkedHashMap<>(16, 0.75F, true);
+    private final ReferenceQueue<Object> collectedSources = new ReferenceQueue<>();
+
+    U get(Object source) {
+        return leastRecentlyUsedFirst.get(Source.lookingFor(source));
+    }
+
+    void put(Object source, U upload) {
+        leastRecentlyUsedFirst.put(new Source(source, collectedSources), upload);
+    }
+
+    void forgetCollected() {
+        for (Reference<?> collected = collectedSources.poll(); collected != null; collected = collectedSources.poll()) {
+            U upload = leastRecentlyUsedFirst.remove(collected);
+            if (upload != null) {
+                upload.delete();
+            }
+        }
+    }
+
+    /**
+     * Deletes the least recently used uploads until the cache fits, sparing those made from what is kept.
+     */
+    void forgetBeyond(long mostBytes, Set<Object> kept) {
+        long bytes = 0L;
+        for (U upload : leastRecentlyUsedFirst.values()) {
+            bytes += upload.bytes();
+        }
+        Iterator<Map.Entry<Source, U>> oldestFirst = leastRecentlyUsedFirst.entrySet().iterator();
+        while (bytes > mostBytes && oldestFirst.hasNext()) {
+            Map.Entry<Source, U> entry = oldestFirst.next();
+            if (!kept.contains(entry.getKey().get())) {
+                bytes -= entry.getValue().bytes();
+                entry.getValue().delete();
+                oldestFirst.remove();
+            }
+        }
+    }
+
+    interface Upload {
+        long bytes();
+
+        void delete();
+    }
+
+    // Equal only to a source of the same object, so a collected one is equal to nothing but itself.
+    private static final class Source extends WeakReference<Object> {
+        private final int identityHash;
+
+        private Source(Object source, ReferenceQueue<Object> collected) {
+            super(source, collected);
+            identityHash = System.identityHashCode(source);
+        }
+
+        static Source lookingFor(Object source) {
+            return new Source(source, null);
+        }
+
+        @Override
+        public int hashCode() {
+            return identityHash;
+        }
+
+        @Override
+        public boolean equals(Object other) {
+            if (this == other) {
+                return true;
+            }
+            Object source = get();
+            return source != null && other instanceof Source otherSource && source == otherSource.get();
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuCanvas.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 art.arcane.iris.studio.map;
+
+import org.lwjgl.system.MemoryStack;
+import org.lwjgl.system.jawt.JAWT;
+import org.lwjgl.system.jawt.JAWTDrawingSurface;
+import org.lwjgl.system.jawt.JAWTDrawingSurfaceInfo;
+import org.lwjgl.system.jawt.JAWTX11DrawingSurfaceInfo;
+
+import javax.swing.SwingUtilities;
+import java.awt.Canvas;
+import java.awt.Component;
+import java.awt.Graphics;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseWheelEvent;
+
+import static org.lwjgl.system.jawt.JAWTFunctions.*;
+
+/**
+ * A native window inside a 3D view that the graphics card draws frames straight into. Swing can't paint over it, so
+ * panels floating over the view are cut out of it, and the view paints what lies behind them itself. The mouse belongs
+ * to the view behind it, as if this window weren't there.
+ */
+final class GpuCanvas extends Canvas {
+    private static final long serialVersionUID = 2874650379461920137L;
+
+    private final transient Component view;
+    private final transient Runnable onExposed;
+    private volatile long window;
+    private volatile long visualId;
+
+    /**
+     * @param onExposed runs on the Swing thread when what the window showed was lost and has to be drawn again
+     */
+    GpuCanvas(Component view, Runnable onExposed) {
+        this.view = view;
+        this.onExposed = onExposed;
+        setFocusable(false);
+        setBackground(StudioTheme.EDITOR_BACKGROUND);
+        handMouseToView();
+    }
+
+    /**
+     * @return the X window frames go into, or 0 while there is none
+     */
+    long window() {
+        return window;
+    }
+
+    long visualId() {
+        return visualId;
+    }
+
+    @Override
+    public void addNotify() {
+        super.addNotify();
+        readNativeWindow();
+    }
+
+    // A frame on its way into the window would otherwise draw into one that no longer exists.
+    @Override
+    public void removeNotify() {
+        long goingWindow = window;
+        window = 0L;
+        if (goingWindow != 0L) {
+            GpuContext.forgetWindow(goingWindow);
+        }
+        super.removeNotify();
+    }
+
+    // Erasing to the background first would flash it between frames.
+    @Override
+    public void update(Graphics graphics) {
+        onExposed.run();
+    }
+
+    @Override
+    public void paint(Graphics graphics) {
+        onExposed.run();
+    }
+
+    private void readNativeWindow() {
+        try (MemoryStack stack = MemoryStack.stackPush()) {
+            JAWT awt = JAWT.calloc(stack).version(JAWT_VERSION_1_4);
+            if (!JAWT_GetAWT(awt)) {
+                return;
+            }
+            JAWTDrawingSurface surface = JAWT_GetDrawingSurface(this, awt.GetDrawingSurface());
+            if (surface == null) {
+                return;
+            }
+            try {
+                readLocked(surface);
+            } finally {
+                JAWT_FreeDrawingSurface(surface, awt.FreeDrawingSurface());
+            }
+        }
+    }
+
+    private void readLocked(JAWTDrawingSurface surface) {
+        if ((JAWT_DrawingSurface_Lock(surface, surface.Lock()) & JAWT_LOCK_ERROR) != 0) {
+            return;
+        }
+        try {
+            JAWTDrawingSurfaceInfo info = JAWT_DrawingSurface_GetDrawingSurfaceInfo(surface, surface.GetDrawingSurfaceInfo());
+            if (info == null) {
+                return;
+            }
+            try {
+                JAWTX11DrawingSurfaceInfo x11 = JAWTX11DrawingSurfaceInfo.create(info.platformInfo());
+                visualId = x11.visualID();
+                window = x11.drawable();
+            } finally {
+                JAWT_DrawingSurface_FreeDrawingSurfaceInfo(info, surface.FreeDrawingSurfaceInfo());
+            }
+        } finally {
+            JAWT_DrawingSurface_Unlock(surface, surface.Unlock());
+        }
+    }
+
+    private void handMouseToView() {
+        MouseAdapter handOver = new MouseAdapter() {
+            @Override
+            public void mousePressed(MouseEvent event) {
+                handOver(event);
+            }
+
+            @Override
+            public void mouseReleased(MouseEvent event) {
+                handOver(event);
+            }
+
+            @Override
+            public void mouseClicked(MouseEvent event) {
+                handOver(event);
+            }
+
+            @Override
+            public void mouseDragged(MouseEvent event) {
+                handOver(event);
+            }
+
+            @Override
+            public void mouseMoved(MouseEvent event) {
+                handOver(event);
+            }
+
+            @Override
+            public void mouseWheelMoved(MouseWheelEvent event) {
+                handOver(event);
+            }
+        };
+        addMouseListener(handOver);
+        addMouseMotionListener(handOver);
+        addMouseWheelListener(handOver);
+    }
+
+    private void handOver(MouseEvent event) {
+        view.dispatchEvent(SwingUtilities.convertMouseEvent(this, event, view));
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuColors.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 art.arcane.iris.studio.map;
+
+import static org.lwjgl.opengl.GL12.*;
+
+/**
+ * Terrain's column colours on the graphics card, one texel per column, so faces running over many columns still colour
+ * each one. Only for the GPU thread.
+ */
+final class GpuColors {
+    private static final int BYTES_PER_COLUMN = 4;
+
+    private final int texture = glGenTextures();
+    private final long bytes;
+
+    private GpuColors(NoiseTerrain terrain) {
+        this.bytes = (long) terrain.columns() * terrain.rows() * BYTES_PER_COLUMN;
+    }
+
+    /**
+     * @param largestSide the card's GL_MAX_TEXTURE_SIZE
+     * @return the colours, or null when the terrain has more columns or rows than the card's textures can hold
+     */
+    static GpuColors upload(NoiseTerrain terrain, int largestSide) {
+        if (terrain.columns() > largestSide || terrain.rows() > largestSide) {
+            return null;
+        }
+        GpuColors uploaded = new GpuColors(terrain);
+        glBindTexture(GL_TEXTURE_2D, uploaded.texture);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, terrain.columns(), terrain.rows(), 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, terrain.colors());
+        return uploaded;
+    }
+
+    long bytes() {
+        return bytes;
+    }
+
+    void bind() {
+        glBindTexture(GL_TEXTURE_2D, texture);
+    }
+
+    void delete() {
+        glDeleteTextures(texture);
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuContext.java

@@ -0,0 +1,279 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.spi.IrisLogging;
+import art.arcane.iris.studio.view.GuiHost;
+import org.lwjgl.PointerBuffer;
+import org.lwjgl.egl.EGL;
+import org.lwjgl.opengl.GL;
+import org.lwjgl.system.Configuration;
+
+import java.util.Arrays;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+import static org.lwjgl.egl.EGL15.*;
+import static org.lwjgl.egl.EXTDeviceEnumeration.eglQueryDevicesEXT;
+import static org.lwjgl.egl.EXTDeviceQuery.eglQueryDeviceStringEXT;
+import static org.lwjgl.egl.EXTPlatformBase.eglGetPlatformDisplayEXT;
+import static org.lwjgl.egl.EXTPlatformDevice.EGL_PLATFORM_DEVICE_EXT;
+import static org.lwjgl.opengl.GL11.GL_RENDERER;
+import static org.lwjgl.opengl.GL11.glGetString;
+
+/**
+ * An OpenGL context on a graphics card, and the one thread allowed to use it. Where Swing draws on X, the context draws
+ * straight into Swing's windows through GLX. Anywhere else, or when GLX only draws in software, it is made through
+ * EGL without any window: EGL lists the cards and the first one that isn't drawn in software is taken.
+ */
+final class GpuContext {
+    private static final String THREAD_NAME = "Iris GPU";
+    private static final long RELEASE_WAIT_SECONDS = 5L;
+    private static final int OPENGL_MAJOR_VERSION = 3;
+    private static final int OPENGL_MINOR_VERSION = 3;
+    private static final String SOFTWARE_DEVICE_EXTENSION = "EGL_MESA_device_software";
+    private static final Set<String> REQUIRED_CLIENT_EXTENSIONS = Set.of("EGL_EXT_device_enumeration", "EGL_EXT_device_query",
+            "EGL_EXT_platform_base", "EGL_EXT_platform_device");
+
+    private static volatile GpuContext shared;
+    private static boolean unavailable;
+
+    private final ExecutorService thread = Executors.newSingleThreadExecutor(runnable -> {
+        Thread gpuThread = new Thread(runnable, THREAD_NAME);
+        gpuThread.setDaemon(true);
+        return gpuThread;
+    });
+    private String renderer;
+    private GlxDisplay windows;
+    private volatile boolean drawsIntoWindows;
+    private long eglDisplay = EGL_NO_DISPLAY;
+    private long eglContext = EGL_NO_CONTEXT;
+
+    private GpuContext() {
+    }
+
+    /**
+     * Whether frames can go straight into windows, as far as is known without opening the context.
+     */
+    static boolean drawsIntoWindows() {
+        GpuContext context = shared;
+        return context != null && context.drawsIntoWindows;
+    }
+
+    /**
+     * Only for the context's thread.
+     *
+     * @return the connection drawing into windows, or nothing when frames are only drawn off screen
+     */
+    Optional<GlxDisplay> windows() {
+        return drawsIntoWindows ? Optional.of(windows) : Optional.empty();
+    }
+
+    /**
+     * Stops drawing into a window about to be destroyed, waiting for a frame going into it to finish first.
+     */
+    static void forgetWindow(long window) {
+        GpuContext context = shared;
+        if (context == null || context.windows == null) {
+            return;
+        }
+        try {
+            context.call(() -> {
+                context.windows.forget(window);
+                return null;
+            });
+        } catch (InterruptedException interrupted) {
+            Thread.currentThread().interrupt();
+        } catch (RuntimeException failure) {
+            IrisLogging.reportError(failure);
+        }
+    }
+
+    // Off-screen frames still work in the same context, read back like on a machine without GLX.
+    void stopDrawingIntoWindows(RuntimeException failure) {
+        if (!drawsIntoWindows) {
+            return;
+        }
+        drawsIntoWindows = false;
+        IrisLogging.reportError(failure);
+        IrisLogging.warn("3D views stop drawing straight into windows: %s", failure.getMessage());
+    }
+
+    /**
+     * @return the context every view shares, opened on first use, or nothing when this machine has no usable card
+     */
+    static synchronized Optional<GpuContext> shared() {
+        if (shared == null && !unavailable) {
+            shared = open();
+            unavailable = shared == null;
+        }
+        return Optional.ofNullable(shared);
+    }
+
+    private static GpuContext open() {
+        GpuContext context = new GpuContext();
+        try {
+            context.thread.submit(context::openOnCard).get();
+            IrisLogging.info(context.drawsIntoWindows ? "3D views draw on %s, straight into their windows" : "3D views draw on %s",
+                    context.renderer);
+            releaseOnShutdown();
+            return context;
+        } catch (ExecutionException failure) {
+            IrisLogging.warn("3D views draw without a graphics card: %s", failure.getCause());
+        } catch (InterruptedException interrupted) {
+            Thread.currentThread().interrupt();
+        }
+        context.thread.shutdownNow();
+        return null;
+    }
+
+    // NVIDIA's driver crashes the JVM on its way out when a context is still current on some thread.
+    private static void releaseOnShutdown() {
+        GuiHost.runAtShutdown(GpuContext::releaseShared);
+    }
+
+    /**
+     * Lets go of the card once frames already asked for are drawn. Frames asked for later are drawn without it.
+     */
+    static synchronized void releaseShared() {
+        GpuContext context = shared;
+        if (context == null) {
+            return;
+        }
+        context.thread.execute(context::release);
+        context.thread.shutdown();
+        try {
+            if (!context.thread.awaitTermination(RELEASE_WAIT_SECONDS, TimeUnit.SECONDS)) {
+                IrisLogging.warn("3D views didn't let go of the graphics card in time");
+            }
+        } catch (InterruptedException interrupted) {
+            Thread.currentThread().interrupt();
+        }
+    }
+
+    private void release() {
+        drawsIntoWindows = false;
+        if (windows != null) {
+            windows.close();
+            return;
+        }
+        eglMakeCurrent(eglDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
+        eglDestroyContext(eglDisplay, eglContext);
+        eglTerminate(eglDisplay);
+        eglReleaseThread();
+    }
+
+    /**
+     * Runs {@code work} on the context's thread and waits for it.
+     */
+    <T> T call(Callable<T> work) throws InterruptedException {
+        try {
+            return thread.submit(work).get();
+        } catch (ExecutionException failure) {
+            throw new IllegalStateException("Drawing on the graphics card failed", failure.getCause());
+        }
+    }
+
+    // GL would otherwise look for a GLX library as soon as it loads, which a context from EGL doesn't use.
+    private Void openOnCard() {
+        Configuration.OPENGL_EXPLICIT_INIT.set(true);
+        try {
+            windows = GlxDisplay.open();
+            renderer = windows.renderer();
+            drawsIntoWindows = true;
+            return null;
+        } catch (RuntimeException | LinkageError noWindows) {
+            IrisLogging.info("3D views can't draw straight into windows: %s", noWindows);
+        }
+        openWithoutWindows();
+        return null;
+    }
+
+    private void openWithoutWindows() {
+        if (!canListDevices()) {
+            throw new IllegalStateException("EGL can't list graphics cards");
+        }
+        GL.create(EGL.getFunctionProvider());
+        for (long device : devices()) {
+            if (!isDrawnInSoftware(device) && makeCurrentOn(device)) {
+                GL.createCapabilities();
+                renderer = glGetString(GL_RENDERER);
+                return;
+            }
+        }
+        throw new IllegalStateException("No graphics card supports OpenGL " + OPENGL_MAJOR_VERSION + "." + OPENGL_MINOR_VERSION);
+    }
+
+    // LWJGL's own capability flags read false for these even where the library has them, so the list is asked for.
+    private static boolean canListDevices() {
+        String extensions = eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
+        return extensions != null && Arrays.asList(extensions.split(" ")).containsAll(REQUIRED_CLIENT_EXTENSIONS);
+    }
+
+    private static long[] devices() {
+        int[] count = new int[1];
+        eglQueryDevicesEXT(null, count);
+        PointerBuffer found = PointerBuffer.allocateDirect(count[0]);
+        eglQueryDevicesEXT(found, count);
+        long[] devices = new long[count[0]];
+        for (int device = 0; device < devices.length; device++) {
+            devices[device] = found.get(device);
+        }
+        return devices;
+    }
+
+    private static boolean isDrawnInSoftware(long device) {
+        String extensions = eglQueryDeviceStringEXT(device, EGL_EXTENSIONS);
+        return extensions != null && extensions.contains(SOFTWARE_DEVICE_EXTENSION);
+    }
+
+    // Nothing is drawn to a surface, only to framebuffers of the context's own, so the context needs none. Configs
+    // default to window surfaces, which a card without a display has none of.
+    private boolean makeCurrentOn(long device) {
+        long display = eglGetPlatformDisplayEXT(EGL_PLATFORM_DEVICE_EXT, device, (int[]) null);
+        if (display == EGL_NO_DISPLAY || !eglInitialize(display, new int[1], new int[1])) {
+            return false;
+        }
+        PointerBuffer config = PointerBuffer.allocateDirect(1);
+        int[] configCount = new int[1];
+        int[] wanted = {EGL_SURFACE_TYPE, EGL_PBUFFER_BIT, EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT, EGL_NONE};
+        if (!eglChooseConfig(display, wanted, config, configCount) || configCount[0] == 0
+                || !eglBindAPI(EGL_OPENGL_API)) {
+            eglTerminate(display);
+            return false;
+        }
+        long context = eglCreateContext(display, config.get(0), EGL_NO_CONTEXT, new int[]{
+                EGL_CONTEXT_MAJOR_VERSION, OPENGL_MAJOR_VERSION,
+                EGL_CONTEXT_MINOR_VERSION, OPENGL_MINOR_VERSION,
+                EGL_CONTEXT_OPENGL_PROFILE_MASK, EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT,
+                EGL_NONE});
+        if (context == EGL_NO_CONTEXT || !eglMakeCurrent(display, EGL_NO_SURFACE, EGL_NO_SURFACE, context)) {
+            eglTerminate(display);
+            return false;
+        }
+        eglDisplay = display;
+        eglContext = context;
+        return true;
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuFaces.java

@@ -0,0 +1,128 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import org.lwjgl.system.MemoryUtil;
+
+import java.nio.IntBuffer;
+
+import static org.lwjgl.opengl.GL33.*;
+
+/**
+ * A layer's block faces on the graphics card, four ints each: first column, first row, bottom, and run with height.
+ * The vertex shader reads them from a buffer texture and works out each face's two triangles itself, which cards draw
+ * far faster than millions of tiny instances. Only for the GPU thread.
+ */
+final class GpuFaces {
+    static final int CORNERS_PER_FACE = 6;
+    private static final int INTS_PER_FACE = 4;
+    private static final int BYTES_PER_FACE = INTS_PER_FACE * Integer.BYTES;
+    private static final int FACES_PER_UPLOAD = 1 << 20;
+    private static final int LARGEST_PACKED = 0xFFFF;
+    private static final BlockFaces.Facing[] FACINGS = BlockFaces.Facing.values();
+    private static final BlockFaces.Kind[] KINDS = BlockFaces.Kind.values();
+
+    // Copied rather than kept, so the faces left in memory can be dropped once nothing else uses them.
+    private final int[][] firstOf = new int[KINDS.length][FACINGS.length];
+    private final int[][] countOf = new int[KINDS.length][FACINGS.length];
+    private final long bytes;
+    private final int buffer = glGenBuffers();
+    private final int texture = glGenTextures();
+
+    private GpuFaces(BlockFaces faces) {
+        for (BlockFaces.Kind kind : KINDS) {
+            for (BlockFaces.Facing facing : FACINGS) {
+                firstOf[kind.ordinal()][facing.ordinal()] = faces.first(kind, facing);
+                countOf[kind.ordinal()][facing.ordinal()] = faces.count(kind, facing);
+            }
+        }
+        bytes = (long) faces.count() * BYTES_PER_FACE;
+    }
+
+    /**
+     * @throws IllegalArgumentException when there are more faces than the card's buffer textures hold, or a face runs
+     *                                  or reaches further than four ints can hold
+     * @param mostFaces the card's GL_MAX_TEXTURE_BUFFER_SIZE
+     */
+    static GpuFaces upload(BlockFaces faces, int mostFaces) {
+        if (faces.count() > mostFaces || (long) faces.count() * CORNERS_PER_FACE > Integer.MAX_VALUE) {
+            throw new IllegalArgumentException(faces.count() + " faces are more than the graphics card can hold");
+        }
+        GpuFaces uploaded = new GpuFaces(faces);
+        try {
+            uploaded.fill(faces);
+        } catch (RuntimeException failure) {
+            uploaded.delete();
+            throw failure;
+        }
+        return uploaded;
+    }
+
+    // Packed a slice at a time, so large terrain doesn't need all of it twice in memory.
+    private void fill(BlockFaces faces) {
+        glBindBuffer(GL_TEXTURE_BUFFER, buffer);
+        glBufferData(GL_TEXTURE_BUFFER, (long) Math.max(1, faces.count()) * BYTES_PER_FACE, GL_STATIC_DRAW);
+        IntBuffer packed = MemoryUtil.memAllocInt(Math.max(1, Math.min(faces.count(), FACES_PER_UPLOAD)) * INTS_PER_FACE);
+        try {
+            for (int from = 0; from < faces.count(); from += FACES_PER_UPLOAD) {
+                int to = Math.min(faces.count(), from + FACES_PER_UPLOAD);
+                pack(faces, packed, from, to);
+                glBufferSubData(GL_TEXTURE_BUFFER, (long) from * BYTES_PER_FACE, packed);
+            }
+        } finally {
+            MemoryUtil.memFree(packed);
+        }
+        glBindTexture(GL_TEXTURE_BUFFER, texture);
+        glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32I, buffer);
+    }
+
+    private static void pack(BlockFaces faces, IntBuffer packed, int fromFace, int toFace) {
+        packed.clear();
+        for (int face = fromFace; face < toFace; face++) {
+            int run = faces.columns(face);
+            int reach = faces.height(face);
+            if (run > LARGEST_PACKED || reach > LARGEST_PACKED) {
+                throw new IllegalArgumentException("A face of " + run + " by " + reach + " is too large to draw on the graphics card");
+            }
+            packed.put(faces.firstColumn(face)).put(faces.firstRow(face)).put(faces.bottomY(face)).put(run | reach << 16);
+        }
+        packed.flip();
+    }
+
+    void bind() {
+        glBindTexture(GL_TEXTURE_BUFFER, texture);
+    }
+
+    int first(BlockFaces.Kind kind, BlockFaces.Facing facing) {
+        return firstOf[kind.ordinal()][facing.ordinal()];
+    }
+
+    int count(BlockFaces.Kind kind, BlockFaces.Facing facing) {
+        return countOf[kind.ordinal()][facing.ordinal()];
+    }
+
+    long bytes() {
+        return bytes;
+    }
+
+    void delete() {
+        glDeleteTextures(texture);
+        glDeleteBuffers(buffer);
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuFrameTarget.java

@@ -0,0 +1,67 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.OptionalDouble;
+
+import static org.lwjgl.opengl.GL11.GL_DEPTH_COMPONENT;
+import static org.lwjgl.opengl.GL11.GL_FLOAT;
+import static org.lwjgl.opengl.GL11.glReadPixels;
+
+/**
+ * Where the graphics card draws a frame: a picture read back for Swing, or straight into a window. Only for the GPU
+ * thread.
+ */
+interface GpuFrameTarget {
+    double FARTHEST_DEPTH = 1D;
+
+    /**
+     * Makes the target the one drawn into, at the given size.
+     */
+    void bindSized(int width, int height);
+
+    /**
+     * Ends the frame drawn since {@link #bindSized}.
+     *
+     * @param depthRange the range the clip matrix was made for
+     */
+    OrbitPicture finish(OrbitProjection projection, double depthRange);
+
+    /**
+     * Reads the one depth a picture keeps, the middle's, from what is bound.
+     */
+    static OptionalDouble depthInMiddle(OrbitProjection projection, double depthRange, int width, int height) {
+        int middleX = (int) projection.screenCenterX();
+        int middleY = (int) projection.screenCenterY();
+        if (middleX < 0 || middleY < 0 || middleX >= width || middleY >= height) {
+            return OptionalDouble.empty();
+        }
+        float[] middleDepth = new float[1];
+        glReadPixels(middleX, height - 1 - middleY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, middleDepth);
+        return OrbitPicture.finite(blockDepth(middleDepth[0], depthRange));
+    }
+
+    // The depth buffer holds 0 at the near plane and 1 at the far one, nearer being smaller.
+    private static double blockDepth(float bufferDepth, double depthRange) {
+        if (bufferDepth >= FARTHEST_DEPTH) {
+            return Double.NEGATIVE_INFINITY;
+        }
+        return -(2D * bufferDepth - 1D) * depthRange;
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuFramebuffer.java

@@ -0,0 +1,73 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.awt.image.BufferedImage;
+import java.awt.image.DataBufferInt;
+
+import static org.lwjgl.opengl.GL30.*;
+
+/**
+ * A picture the graphics card draws into instead of a window, read back as an {@link OrbitPicture} so Swing shows it
+ * like any other. Only for the GPU thread.
+ */
+final class GpuFramebuffer implements GpuFrameTarget {
+    private final int framebuffer = glGenFramebuffers();
+    private final int colorBuffer = glGenRenderbuffers();
+    private final int depthBuffer = glGenRenderbuffers();
+    private int width;
+    private int height;
+    private int[] colorRows = new int[0];
+
+    @Override
+    public void bindSized(int nextWidth, int nextHeight) {
+        glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
+        if (nextWidth != width || nextHeight != height) {
+            resizeTo(nextWidth, nextHeight);
+        }
+        glViewport(0, 0, width, height);
+    }
+
+    private void resizeTo(int nextWidth, int nextHeight) {
+        width = nextWidth;
+        height = nextHeight;
+        glBindRenderbuffer(GL_RENDERBUFFER, colorBuffer);
+        glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, width, height);
+        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorBuffer);
+        glBindRenderbuffer(GL_RENDERBUFFER, depthBuffer);
+        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height);
+        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthBuffer);
+        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+            throw new IllegalStateException("The graphics card can't draw a " + width + "x" + height + " picture");
+        }
+        colorRows = new int[width * height];
+    }
+
+    // Reads what was drawn. Only the middle's depth is read back, the one depth a picture keeps.
+    @Override
+    public OrbitPicture finish(OrbitProjection projection, double depthRange) {
+        glReadPixels(0, 0, width, height, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, colorRows);
+        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
+        int[] pixels = ((DataBufferInt) image.getRaster().getDataBuffer()).getData();
+        for (int row = 0; row < height; row++) {
+            System.arraycopy(colorRows, (height - 1 - row) * width, pixels, row * width, width);
+        }
+        return OrbitPicture.whole(image, GpuFrameTarget.depthInMiddle(projection, depthRange, width, height));
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuFrames.java

@@ -0,0 +1,151 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.spi.IrisLogging;
+
+import java.util.Optional;
+
+import static org.lwjgl.opengl.GL33.*;
+
+/**
+ * Runs a 3D view's frame on the graphics card, straight into the view's window where frames can go there, or else into
+ * a picture read back for Swing. A card that fails once isn't used again, as it would most likely fail every frame,
+ * each time only after costing the frame its time.
+ */
+final class GpuFrames {
+    private static final double COLOR_CHANNEL_MAX = 255D;
+
+    private static GpuFramebuffer offScreen;
+    private static volatile boolean failed;
+
+    private GpuFrames() {
+    }
+
+    /**
+     * A frame drawn on the card's thread.
+     */
+    @FunctionalInterface
+    interface Drawing {
+        /**
+         * @return the frame, or nothing when the card can't draw this scene and it should be drawn without one
+         */
+        Optional<OrbitPicture> drawInto(GpuFrameTarget target);
+    }
+
+    /**
+     * @return the picture, or nothing when the caller should draw it without a card
+     */
+    static Optional<OrbitPicture> drawPicture(Drawing drawing) {
+        return onCard(gpu -> drawing.drawInto(offScreenFramebuffer()));
+    }
+
+    static boolean canDrawOnScreen() {
+        return !failed && GpuContext.drawsIntoWindows();
+    }
+
+    /**
+     * @return the frame, or nothing when it can't go straight into the window and the caller should draw a picture
+     */
+    static Optional<OrbitPicture> drawOnScreen(ScreenTarget screen, Drawing drawing) {
+        return onCard(gpu -> {
+            Optional<GlxDisplay> windows = gpu.windows();
+            long window = screen.canvas().window();
+            if (windows.isEmpty() || window == 0L) {
+                return Optional.empty();
+            }
+            try {
+                if (!windows.get().canDrawInto(screen.canvas().visualId())) {
+                    throw new IllegalStateException("The view's window has another visual than the one GLX draws with");
+                }
+                if (!windows.get().drawInto(window)) {
+                    throw new IllegalStateException("GLX can't draw into the view's window");
+                }
+                return drawing.drawInto(new GpuWindowFrame(windows.get(), window, screen.seeThrough()));
+            } catch (RuntimeException failure) {
+                gpu.stopDrawingIntoWindows(failure);
+                return Optional.empty();
+            }
+        });
+    }
+
+    static void failOnError() {
+        int error = glGetError();
+        if (error != GL_NO_ERROR) {
+            throw new IllegalStateException("OpenGL error 0x" + Integer.toHexString(error));
+        }
+    }
+
+    /**
+     * Clears to the views' background, and sets up for opaque drawing with depth.
+     */
+    static void clearToBackground() {
+        int background = StudioTheme.EDITOR_BACKGROUND.getRGB();
+        glClearColor(channel(background, 16), channel(background, 8), channel(background, 0), 1F);
+        glClearDepth(1D);
+        glDepthMask(true);
+        glEnable(GL_DEPTH_TEST);
+        glDepthFunc(GL_LESS);
+        glDisable(GL_BLEND);
+        glDisable(GL_CULL_FACE);
+        glDisable(GL_POLYGON_OFFSET_FILL);
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    }
+
+    static float channel(int color, int shift) {
+        return (float) (((color >>> shift) & 0xFF) / COLOR_CHANNEL_MAX);
+    }
+
+    private static GpuFramebuffer offScreenFramebuffer() {
+        if (offScreen == null) {
+            offScreen = new GpuFramebuffer();
+        }
+        return offScreen;
+    }
+
+    private static Optional<OrbitPicture> onCard(CardWork work) {
+        if (failed) {
+            return Optional.empty();
+        }
+        Optional<GpuContext> gpu = GpuContext.shared();
+        if (gpu.isEmpty()) {
+            return Optional.empty();
+        }
+        try {
+            return gpu.get().call(() -> work.drawOn(gpu.get()));
+        } catch (InterruptedException interrupted) {
+            Thread.currentThread().interrupt();
+            return Optional.empty();
+        } catch (RuntimeException failure) {
+            stopUsingCard(failure);
+            return Optional.empty();
+        }
+    }
+
+    private static void stopUsingCard(RuntimeException failure) {
+        failed = true;
+        IrisLogging.reportError(failure);
+        IrisLogging.warn("3D views draw without a graphics card from now on: %s", failure.getCause() == null ? failure : failure.getCause());
+    }
+
+    @FunctionalInterface
+    private interface CardWork {
+        Optional<OrbitPicture> drawOn(GpuContext gpu);
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuLibrary.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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.spi.IrisLogging;
+
+import java.util.List;
+
+/**
+ * Whether the graphics card library the 3D views draw with is on the classpath. Mod loaders get it from the game,
+ * which ships only part of it, so the views check here before touching any class that links against it.
+ */
+final class GpuLibrary {
+    private static final List<String> REQUIRED_CLASSES = List.of(
+            "org.lwjgl.system.MemoryStack",
+            "org.lwjgl.opengl.GL",
+            "org.lwjgl.egl.EGL",
+            "org.lwjgl.system.jawt.JAWT"
+    );
+    private static final boolean LOADED = findRequiredClasses();
+
+    private GpuLibrary() {
+    }
+
+    static boolean isLoaded() {
+        return LOADED;
+    }
+
+    private static boolean findRequiredClasses() {
+        ClassLoader loader = GpuLibrary.class.getClassLoader();
+        for (String className : REQUIRED_CLASSES) {
+            try {
+                Class.forName(className, false, loader);
+            } catch (ClassNotFoundException | LinkageError missing) {
+                IrisLogging.info("3D views draw without a graphics card: %s isn't on the classpath", className);
+                return false;
+            }
+        }
+        return true;
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuObjectMesh.java

@@ -0,0 +1,279 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.BlockModel.Face;
+import art.arcane.iris.studio.map.BlockModel.TextureMapping;
+import art.arcane.iris.studio.map.BlockTextures.BlockTexture;
+import org.lwjgl.system.MemoryUtil;
+
+import java.nio.FloatBuffer;
+import java.nio.IntBuffer;
+import java.util.Arrays;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.lwjgl.opengl.GL33.*;
+
+/**
+ * An object mesh's quads and the texels of their textures on the graphics card, each in a buffer texture the shaders
+ * read from. Quads come solid first, then the cut-away ghost, then the see-through ones, whose drawing order is sent
+ * again every frame, farthest first. Only for the GPU thread.
+ */
+final class GpuObjectMesh implements GpuCache.Upload {
+    static final int TEXELS_PER_QUAD = 7;
+    private static final int FLOATS_PER_QUAD = TEXELS_PER_QUAD * 4;
+    private static final int OPAQUE_ALPHA = 0xFF;
+
+    private final Vec3 anchor;
+    private final int solidCount;
+    private final int ghostCount;
+    private final int seeThroughCount;
+    private final float[] seeThroughCenters;
+    private final long bytes;
+    private final int quadBuffer = glGenBuffers();
+    private final int quadTexture = glGenTextures();
+    private final int texelBuffer = glGenBuffers();
+    private final int texelTexture = glGenTextures();
+    private final int orderBuffer = glGenBuffers();
+    private final int orderTexture = glGenTextures();
+
+    private GpuObjectMesh(ObjectMesh mesh, int texelCount) {
+        ObjectMesh.Bounds bounds = mesh.bounds();
+        anchor = new Vec3(bounds.minX(), bounds.minY(), bounds.minZ());
+        solidCount = mesh.solidQuads().size();
+        ghostCount = mesh.cutAwayQuads().size();
+        seeThroughCount = mesh.translucentQuads().size();
+        seeThroughCenters = centersOf(mesh.translucentQuads());
+        bytes = (long) quadCount() * FLOATS_PER_QUAD * Float.BYTES + (long) texelCount * Integer.BYTES + (long) seeThroughCount * Integer.BYTES;
+    }
+
+    /**
+     * @param mostTexels the card's GL_MAX_TEXTURE_BUFFER_SIZE
+     * @return the uploaded mesh, or null when it is more than the card's buffer textures hold
+     */
+    static GpuObjectMesh upload(ObjectMesh mesh, int mostTexels) {
+        Map<BlockTexture, Integer> textureOffsets = new IdentityHashMap<>();
+        int texelCount = placeTextures(mesh, textureOffsets);
+        long quadTexels = (long) (mesh.solidQuads().size() + mesh.cutAwayQuads().size() + mesh.translucentQuads().size()) * TEXELS_PER_QUAD;
+        if (quadTexels > mostTexels || texelCount > mostTexels || quadTexels * 6L > Integer.MAX_VALUE) {
+            return null;
+        }
+        GpuObjectMesh uploaded = new GpuObjectMesh(mesh, texelCount);
+        try {
+            uploaded.fillQuads(mesh, textureOffsets);
+            uploaded.fillTexels(textureOffsets, texelCount);
+            uploaded.prepareOrder();
+        } catch (RuntimeException failure) {
+            uploaded.delete();
+            throw failure;
+        }
+        return uploaded;
+    }
+
+    private static int placeTextures(ObjectMesh mesh, Map<BlockTexture, Integer> offsets) {
+        int texelCount = 0;
+        for (List<ObjectMesh.Quad> quads : List.of(mesh.solidQuads(), mesh.cutAwayQuads(), mesh.translucentQuads())) {
+            for (ObjectMesh.Quad quad : quads) {
+                BlockTexture texture = quad.face().texture();
+                if (!offsets.containsKey(texture)) {
+                    offsets.put(texture, texelCount);
+                    texelCount += texture.width() * texture.height();
+                }
+            }
+        }
+        return texelCount;
+    }
+
+    private float[] centersOf(List<ObjectMesh.Quad> quads) {
+        float[] centers = new float[quads.size() * 3];
+        for (int index = 0; index < quads.size(); index++) {
+            ObjectMesh.Quad quad = quads.get(index);
+            Face face = quad.face();
+            centers[index * 3] = (float) (quad.originX() - anchor.x() + (face.edgeU().x() + face.edgeV().x()) / 2D);
+            centers[index * 3 + 1] = (float) (quad.originY() - anchor.y() + (face.edgeU().y() + face.edgeV().y()) / 2D);
+            centers[index * 3 + 2] = (float) (quad.originZ() - anchor.z() + (face.edgeU().z() + face.edgeV().z()) / 2D);
+        }
+        return centers;
+    }
+
+    private void fillQuads(ObjectMesh mesh, Map<BlockTexture, Integer> textureOffsets) {
+        FloatBuffer packed = MemoryUtil.memAllocFloat(Math.max(1, quadCount()) * FLOATS_PER_QUAD);
+        try {
+            for (List<ObjectMesh.Quad> quads : List.of(mesh.solidQuads(), mesh.cutAwayQuads(), mesh.translucentQuads())) {
+                for (ObjectMesh.Quad quad : quads) {
+                    pack(quad, textureOffsets.get(quad.face().texture()), packed);
+                }
+            }
+            packed.flip();
+            glBindBuffer(GL_TEXTURE_BUFFER, quadBuffer);
+            glBufferData(GL_TEXTURE_BUFFER, packed, GL_STATIC_DRAW);
+        } finally {
+            MemoryUtil.memFree(packed);
+        }
+        glBindTexture(GL_TEXTURE_BUFFER, quadTexture);
+        glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, quadBuffer);
+    }
+
+    // Whole numbers ride along as float bits, read back exactly by the shader.
+    private void pack(ObjectMesh.Quad quad, int textureOffset, FloatBuffer packed) {
+        Face face = quad.face();
+        BlockTexture texture = face.texture();
+        TextureMapping mapping = face.mapping();
+        ObjectRenderer.TexelRange columns = ObjectRenderer.TexelRange.of(mapping.u(), mapping.uAlongU(), mapping.uAlongV(), texture.width());
+        ObjectRenderer.TexelRange rows = ObjectRenderer.TexelRange.of(mapping.v(), mapping.vAlongU(), mapping.vAlongV(), texture.height());
+        put(packed, quad.originX() - anchor.x(), quad.originY() - anchor.y(), quad.originZ() - anchor.z()).put((float) face.shade());
+        put(packed, face.edgeU()).put((float) quad.opacity());
+        put(packed, face.edgeV()).put(Float.intBitsToFloat(textureOffset));
+        put(packed, face.normal()).put(Float.intBitsToFloat(texture.width()));
+        put(packed, mapping.u(), mapping.uAlongU(), mapping.uAlongV()).put(Float.intBitsToFloat(texture.height()));
+        put(packed, mapping.v(), mapping.vAlongU(), mapping.vAlongV()).put(0F);
+        packed.put(Float.intBitsToFloat(columns.first())).put(Float.intBitsToFloat(columns.last()))
+                .put(Float.intBitsToFloat(rows.first())).put(Float.intBitsToFloat(rows.last()));
+    }
+
+    private static FloatBuffer put(FloatBuffer packed, Vec3 vector) {
+        return put(packed, vector.x(), vector.y(), vector.z());
+    }
+
+    private static FloatBuffer put(FloatBuffer packed, double x, double y, double z) {
+        return packed.put((float) x).put((float) y).put((float) z);
+    }
+
+    // Texels the game doesn't draw are fully transparent, so the shader skips them.
+    private void fillTexels(Map<BlockTexture, Integer> textureOffsets, int texelCount) {
+        IntBuffer packed = MemoryUtil.memAllocInt(Math.max(1, texelCount));
+        try {
+            textureOffsets.forEach((texture, offset) -> {
+                int[] alphas = texture.alphas();
+                for (int texel = 0; texel < texture.width() * texture.height(); texel++) {
+                    int alpha = !texture.opaque()[texel] ? 0 : alphas == null ? OPAQUE_ALPHA : alphas[texel];
+                    packed.put(offset + texel, rgba(texture.pixels()[texel], alpha));
+                }
+            });
+            glBindBuffer(GL_TEXTURE_BUFFER, texelBuffer);
+            glBufferData(GL_TEXTURE_BUFFER, packed, GL_STATIC_DRAW);
+        } finally {
+            MemoryUtil.memFree(packed);
+        }
+        glBindTexture(GL_TEXTURE_BUFFER, texelTexture);
+        glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA8, texelBuffer);
+    }
+
+    // GL_RGBA8 takes red from the lowest byte, which is the first in memory on the little-endian machines LWJGL runs on.
+    private static int rgba(int rgb, int alpha) {
+        return ((rgb >>> 16) & 0xFF) | (rgb & 0xFF00) | ((rgb & 0xFF) << 16) | (alpha << 24);
+    }
+
+    private void prepareOrder() {
+        glBindBuffer(GL_TEXTURE_BUFFER, orderBuffer);
+        glBufferData(GL_TEXTURE_BUFFER, (long) Math.max(1, seeThroughCount) * Integer.BYTES, GL_STREAM_DRAW);
+        glBindTexture(GL_TEXTURE_BUFFER, orderTexture);
+        glTexBuffer(GL_TEXTURE_BUFFER, GL_R32I, orderBuffer);
+    }
+
+    /**
+     * Sends the see-through quads' drawing order, farthest from the camera first, keeping the mesh's order between
+     * quads at the same depth.
+     *
+     * @param towardCamera how far each block along x, y and z brings a point toward the camera
+     */
+    void sortSeeThroughFarthestFirst(Vec3 towardCamera) {
+        if (seeThroughCount == 0) {
+            return;
+        }
+        long[] depthThenIndex = new long[seeThroughCount];
+        for (int index = 0; index < seeThroughCount; index++) {
+            float depth = (float) (seeThroughCenters[index * 3] * towardCamera.x() + seeThroughCenters[index * 3 + 1] * towardCamera.y()
+                    + seeThroughCenters[index * 3 + 2] * towardCamera.z());
+            depthThenIndex[index] = (long) sortableBits(depth) << 32 | index;
+        }
+        Arrays.sort(depthThenIndex);
+        IntBuffer order = MemoryUtil.memAllocInt(seeThroughCount);
+        try {
+            int firstSeeThrough = firstSeeThrough();
+            for (long entry : depthThenIndex) {
+                order.put(firstSeeThrough + (int) entry);
+            }
+            order.flip();
+            glBindBuffer(GL_TEXTURE_BUFFER, orderBuffer);
+            glBufferSubData(GL_TEXTURE_BUFFER, 0L, order);
+        } finally {
+            MemoryUtil.memFree(order);
+        }
+    }
+
+    // Ordered as signed ints the way the floats are ordered.
+    private static int sortableBits(float value) {
+        int bits = Float.floatToIntBits(value);
+        return bits < 0 ? bits ^ Integer.MAX_VALUE : bits;
+    }
+
+    void bindQuads() {
+        glBindTexture(GL_TEXTURE_BUFFER, quadTexture);
+    }
+
+    void bindTexels() {
+        glBindTexture(GL_TEXTURE_BUFFER, texelTexture);
+    }
+
+    void bindOrder() {
+        glBindTexture(GL_TEXTURE_BUFFER, orderTexture);
+    }
+
+    Vec3 anchor() {
+        return anchor;
+    }
+
+    int solidCount() {
+        return solidCount;
+    }
+
+    int firstGhost() {
+        return solidCount;
+    }
+
+    int ghostCount() {
+        return ghostCount;
+    }
+
+    int firstSeeThrough() {
+        return solidCount + ghostCount;
+    }
+
+    int seeThroughCount() {
+        return seeThroughCount;
+    }
+
+    private int quadCount() {
+        return solidCount + ghostCount + seeThroughCount;
+    }
+
+    @Override
+    public long bytes() {
+        return bytes;
+    }
+
+    @Override
+    public void delete() {
+        glDeleteTextures(new int[]{quadTexture, texelTexture, orderTexture});
+        glDeleteBuffers(new int[]{quadBuffer, texelBuffer, orderBuffer});
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuObjectRenderer.java

@@ -0,0 +1,279 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.Optional;
+import java.util.Set;
+
+import static org.lwjgl.opengl.GL33.*;
+
+/**
+ * Draws an object mesh on the graphics card, looking the way {@link ObjectRenderer} draws it. That one still draws on
+ * machines without a card, and the thumbnails. The mesh stays on the card while it is shown, so a frame only sends the
+ * camera and the see-through quads' order.
+ */
+final class GpuObjectRenderer {
+    private static final double DEPTH_MARGIN_BLOCKS = 4D;
+    // Several large objects, well within what any card able to draw them has.
+    private static final long MOST_UPLOADED_BYTES = 256L << 20;
+    private static final int CORNERS_PER_QUAD = 6;
+    private static final int ENDS_PER_LINE = 2;
+    private static final int GRID_DIRECTIONS = 2;
+
+    private static final String QUAD_VERTEX_SHADER = """
+            #version 330 core
+            const int[6] CORNERS = int[6](0, 1, 2, 2, 1, 3);
+            const int TEXELS_PER_QUAD = %d;
+            uniform samplerBuffer quads;
+            uniform isamplerBuffer order;
+            uniform bool inOrder;
+            uniform int firstQuad;
+            uniform mat4 toClip;
+            uniform vec3 anchorFromCenter;
+            uniform vec3 towardCamera;
+            out vec2 texturePosition;
+            flat out int firstTexel;
+            flat out ivec2 textureSize;
+            flat out ivec4 texelRange;
+            flat out float shade;
+            flat out float opacity;
+
+            // Faces looking away from the camera are hidden behind the ones looking toward it, so every corner of
+            // theirs is put in the same spot outside the view, which draws nothing.
+            void main() {
+                int index = gl_VertexID / 6;
+                int quad = inOrder ? texelFetch(order, index).r : firstQuad + index;
+                int base = quad * TEXELS_PER_QUAD;
+                vec4 origin = texelFetch(quads, base);
+                vec4 edgeU = texelFetch(quads, base + 1);
+                vec4 edgeV = texelFetch(quads, base + 2);
+                vec4 normal = texelFetch(quads, base + 3);
+                if (dot(normal.xyz, towardCamera) <= 0.0) {
+                    gl_Position = vec4(2.0, 2.0, 2.0, 1.0);
+                    return;
+                }
+                vec4 mappingU = texelFetch(quads, base + 4);
+                vec4 mappingV = texelFetch(quads, base + 5);
+                int corner = CORNERS[gl_VertexID %% 6];
+                float alongU = float(corner & 1);
+                float alongV = float(corner >> 1);
+                gl_Position = toClip * vec4(anchorFromCenter + origin.xyz + alongU * edgeU.xyz + alongV * edgeV.xyz, 1.0);
+                texturePosition = vec2(mappingU.x + alongU * mappingU.y + alongV * mappingU.z,
+                        mappingV.x + alongU * mappingV.y + alongV * mappingV.z);
+                firstTexel = floatBitsToInt(edgeV.w);
+                textureSize = ivec2(floatBitsToInt(normal.w), floatBitsToInt(mappingU.w));
+                texelRange = floatBitsToInt(texelFetch(quads, base + 6));
+                shade = origin.w;
+                opacity = edgeU.w;
+            }
+            """.formatted(GpuObjectMesh.TEXELS_PER_QUAD);
+
+    private static final String QUAD_FRAGMENT_SHADER = """
+            #version 330 core
+            uniform samplerBuffer texels;
+            uniform bool blended;
+            in vec2 texturePosition;
+            flat in int firstTexel;
+            flat in ivec2 textureSize;
+            flat in ivec4 texelRange;
+            flat in float shade;
+            flat in float opacity;
+            out vec4 fragment;
+
+            void main() {
+                int column = clamp(int(floor(texturePosition.x * float(textureSize.x))), texelRange.x, texelRange.y);
+                int row = clamp(int(floor(texturePosition.y * float(textureSize.y))), texelRange.z, texelRange.w);
+                vec4 texel = texelFetch(texels, firstTexel + row * textureSize.x + column);
+                if (texel.a == 0.0) {
+                    discard;
+                }
+                fragment = vec4(min(texel.rgb * shade, vec3(1.0)), blended ? texel.a * opacity : 1.0);
+            }
+            """;
+
+    private static final String GRID_VERTEX_SHADER = """
+            #version 330 core
+            uniform mat4 toClip;
+            uniform vec3 gridCenter;
+            uniform int reach;
+            uniform int step;
+            uniform int linesPerDirection;
+
+            void main() {
+                int line = gl_VertexID / 2;
+                float across = float(-reach + (line % linesPerDirection) * step);
+                float along = float((gl_VertexID % 2) * 2 - 1) * float(reach);
+                vec3 offset = line < linesPerDirection ? vec3(across, 0.0, along) : vec3(along, 0.0, across);
+                gl_Position = toClip * vec4(gridCenter + offset, 1.0);
+            }
+            """;
+
+    private static final String FLAT_FRAGMENT_SHADER = """
+            #version 330 core
+            uniform vec4 color;
+            out vec4 fragment;
+
+            void main() {
+                fragment = color;
+            }
+            """;
+
+    private static GpuObjectRenderer onCard;
+
+    private final GpuProgram quadProgram = GpuProgram.of(QUAD_VERTEX_SHADER, QUAD_FRAGMENT_SHADER);
+    private final GpuProgram gridProgram = GpuProgram.of(GRID_VERTEX_SHADER, FLAT_FRAGMENT_SHADER);
+    private final int attributelessVertexArray = glGenVertexArrays();
+    // Asked once: asking the card waits for everything sent to it so far.
+    private final int mostBufferTexels = glGetInteger(GL_MAX_TEXTURE_BUFFER_SIZE);
+    private final GpuCache<GpuObjectMesh> uploadedMeshes = new GpuCache<>();
+
+    /**
+     * @return the picture, or nothing when the card can't draw this mesh and the caller should draw it without one
+     */
+    static Optional<OrbitPicture> render(ObjectMesh mesh, OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        return GpuFrames.drawPicture(target -> onCard().draw(mesh, camera, width, height, coveredLeftWidth, target));
+    }
+
+    /**
+     * @return the frame, or nothing when it can't go straight into the window and the caller should draw a picture
+     */
+    static Optional<OrbitPicture> renderOnScreen(ObjectMesh mesh, ScreenTarget screen, OrbitCamera camera, int width, int height,
+                                                 int coveredLeftWidth) {
+        return GpuFrames.drawOnScreen(screen, target -> onCard().draw(mesh, camera, width, height, coveredLeftWidth, target));
+    }
+
+    private static GpuObjectRenderer onCard() {
+        if (onCard == null) {
+            onCard = new GpuObjectRenderer();
+        }
+        return onCard;
+    }
+
+    private Optional<OrbitPicture> draw(ObjectMesh mesh, OrbitCamera camera, int width, int height, int coveredLeftWidth,
+                                        GpuFrameTarget target) {
+        GpuObjectMesh uploaded = uploaded(mesh);
+        if (uploaded == null) {
+            return Optional.empty();
+        }
+        OrbitProjection projection = ObjectRenderer.projection(mesh, camera, width, height, coveredLeftWidth);
+        ObjectRenderer.FloorGrid grid = ObjectRenderer.FloorGrid.under(mesh.bounds());
+        double depthRange = farthestFrom(projection.center(), mesh.bounds(), grid) + DEPTH_MARGIN_BLOCKS;
+        float[] toClip = projection.clipMatrix(width, height, depthRange);
+        target.bindSized(width, height);
+        GpuFrames.clearToBackground();
+        glDepthFunc(GL_LEQUAL);
+        glBindVertexArray(attributelessVertexArray);
+        drawGrid(grid, projection, toClip);
+        drawMesh(uploaded, projection, toClip);
+        GpuFrames.failOnError();
+        return Optional.of(target.finish(projection, depthRange));
+    }
+
+    private GpuObjectMesh uploaded(ObjectMesh mesh) {
+        uploadedMeshes.forgetCollected();
+        GpuObjectMesh uploaded = uploadedMeshes.get(mesh);
+        if (uploaded == null) {
+            uploaded = GpuObjectMesh.upload(mesh, mostBufferTexels);
+            if (uploaded == null) {
+                return null;
+            }
+            uploadedMeshes.put(mesh, uploaded);
+        }
+        uploadedMeshes.forgetBeyond(MOST_UPLOADED_BYTES, Set.of(mesh));
+        return uploaded;
+    }
+
+    // No point of the scene is further from the projection's centre than the farthest corner of a box around it all.
+    private static double farthestFrom(Vec3 center, ObjectMesh.Bounds bounds, ObjectRenderer.FloorGrid grid) {
+        double reachX = Math.max(Math.abs(bounds.minX() - center.x()), Math.abs(bounds.maxX() - center.x()));
+        double reachZ = Math.max(Math.abs(bounds.minZ() - center.z()), Math.abs(bounds.maxZ() - center.z()));
+        double gridReachX = Math.abs(grid.centerX() - center.x()) + grid.reach();
+        double gridReachZ = Math.abs(grid.centerZ() - center.z()) + grid.reach();
+        double reachY = Math.max(Math.abs(Math.min(bounds.minY(), grid.floorY()) - center.y()), Math.abs(bounds.maxY() - center.y()));
+        return Math.sqrt(square(Math.max(reachX, gridReachX)) + square(reachY) + square(Math.max(reachZ, gridReachZ)));
+    }
+
+    private static double square(double value) {
+        return value * value;
+    }
+
+    private void drawGrid(ObjectRenderer.FloorGrid grid, OrbitProjection projection, float[] toClip) {
+        Vec3 center = projection.center();
+        int color = grid.color();
+        gridProgram.use();
+        gridProgram.setMatrix("toClip", toClip);
+        gridProgram.set("gridCenter", new Vec3(grid.centerX() - center.x(), grid.floorY() - center.y(), grid.centerZ() - center.z()));
+        gridProgram.set("reach", grid.reach());
+        gridProgram.set("step", grid.step());
+        gridProgram.set("linesPerDirection", grid.linesPerDirection());
+        gridProgram.set("color", GpuFrames.channel(color, 16), GpuFrames.channel(color, 8), GpuFrames.channel(color, 0), 1D);
+        glDrawArrays(GL_LINES, 0, grid.linesPerDirection() * GRID_DIRECTIONS * ENDS_PER_LINE);
+    }
+
+    /**
+     * The cut-away ghost is drawn first, hiding nothing, so the solid quads drawn over it replace it wherever the object
+     * shows. Later quads win ties, so an overlay on the same box, like grass on a grass block's side, shows on top.
+     */
+    private void drawMesh(GpuObjectMesh mesh, OrbitProjection projection, float[] toClip) {
+        Vec3 towardCamera = new Vec3(projection.depthStep(1D, 0D, 0D), projection.depthStep(0D, 1D, 0D), projection.depthStep(0D, 0D, 1D));
+        Vec3 anchor = mesh.anchor();
+        Vec3 center = projection.center();
+        quadProgram.use();
+        quadProgram.setMatrix("toClip", toClip);
+        quadProgram.set("anchorFromCenter", new Vec3(anchor.x() - center.x(), anchor.y() - center.y(), anchor.z() - center.z()));
+        quadProgram.set("towardCamera", towardCamera);
+        quadProgram.set("quads", 0);
+        quadProgram.set("texels", 1);
+        quadProgram.set("order", 2);
+        glActiveTexture(GL_TEXTURE0);
+        mesh.bindQuads();
+        glActiveTexture(GL_TEXTURE1);
+        mesh.bindTexels();
+        glActiveTexture(GL_TEXTURE2);
+        mesh.bindOrder();
+        glActiveTexture(GL_TEXTURE0);
+
+        startBlending();
+        drawQuads(mesh.firstGhost(), mesh.ghostCount(), true);
+        glDisable(GL_BLEND);
+        glDepthMask(true);
+        drawQuads(0, mesh.solidCount(), false);
+        startBlending();
+        mesh.sortSeeThroughFarthestFirst(towardCamera);
+        quadProgram.set("inOrder", 1);
+        drawQuads(0, mesh.seeThroughCount(), true);
+        quadProgram.set("inOrder", 0);
+    }
+
+    // Blended quads hide nothing behind them. The window's own alpha is left whole, so nothing behind it shows through.
+    private static void startBlending() {
+        glEnable(GL_BLEND);
+        glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ZERO, GL_ONE);
+        glDepthMask(false);
+    }
+
+    private void drawQuads(int firstQuad, int count, boolean blended) {
+        if (count == 0) {
+            return;
+        }
+        quadProgram.set("firstQuad", firstQuad);
+        quadProgram.set("blended", blended ? 1 : 0);
+        glDrawArrays(GL_TRIANGLES, 0, count * CORNERS_PER_QUAD);
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuProgram.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 art.arcane.iris.studio.map;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.lwjgl.opengl.GL20.*;
+
+/**
+ * A vertex and a fragment shader linked into one program, with its uniforms set by name. Only for the GPU thread.
+ */
+final class GpuProgram {
+    private final int id;
+    private final Map<String, Integer> uniformLocations = new HashMap<>();
+
+    private GpuProgram(int id) {
+        this.id = id;
+    }
+
+    static GpuProgram of(String vertexSource, String fragmentSource) {
+        int vertexShader = compile(GL_VERTEX_SHADER, vertexSource);
+        int fragmentShader = compile(GL_FRAGMENT_SHADER, fragmentSource);
+        int program = glCreateProgram();
+        glAttachShader(program, vertexShader);
+        glAttachShader(program, fragmentShader);
+        glLinkProgram(program);
+        glDeleteShader(vertexShader);
+        glDeleteShader(fragmentShader);
+        if (glGetProgrami(program, GL_LINK_STATUS) == GL_FALSE) {
+            String log = glGetProgramInfoLog(program);
+            glDeleteProgram(program);
+            throw new IllegalStateException("Linking a shader program failed: " + log);
+        }
+        return new GpuProgram(program);
+    }
+
+    private static int compile(int type, String source) {
+        int shader = glCreateShader(type);
+        glShaderSource(shader, source);
+        glCompileShader(shader);
+        if (glGetShaderi(shader, GL_COMPILE_STATUS) == GL_FALSE) {
+            String log = glGetShaderInfoLog(shader);
+            glDeleteShader(shader);
+            throw new IllegalStateException("Compiling a shader failed: " + log);
+        }
+        return shader;
+    }
+
+    void use() {
+        glUseProgram(id);
+    }
+
+    void set(String name, int value) {
+        glUniform1i(location(name), value);
+    }
+
+    void set(String name, int x, int y) {
+        glUniform2i(location(name), x, y);
+    }
+
+    void set(String name, int x, int y, int z) {
+        glUniform3i(location(name), x, y, z);
+    }
+
+    void set(String name, int[] values) {
+        glUniform1iv(location(name), values);
+    }
+
+    void set(String name, double value) {
+        glUniform1f(location(name), (float) value);
+    }
+
+    void set(String name, Vec3 value) {
+        glUniform3f(location(name), (float) value.x(), (float) value.y(), (float) value.z());
+    }
+
+    void set(String name, double red, double green, double blue, double alpha) {
+        glUniform4f(location(name), (float) red, (float) green, (float) blue, (float) alpha);
+    }
+
+    void setMatrix(String name, float[] columnMajor) {
+        glUniformMatrix4fv(location(name), false, columnMajor);
+    }
+
+    private int location(String name) {
+        return uniformLocations.computeIfAbsent(name, uniform -> glGetUniformLocation(id, uniform));
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuTerrainRenderer.java

@@ -0,0 +1,382 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+
+import static org.lwjgl.opengl.GL33.*;
+
+/**
+ * Draws noise terrain as block columns on the graphics card, looking the way {@link NoiseTerrainRenderer} draws them.
+ * That one still draws on machines without a card. Faces and colours stay on the card while the scene shows them, so
+ * a frame only sends the camera.
+ */
+final class GpuTerrainRenderer {
+    private static final double DEPTH_MARGIN_BLOCKS = 16D;
+    // A few full views' worth, well within what any card able to draw them has.
+    private static final long MOST_UPLOADED_BYTES = 768L << 20;
+    // Half a frame at 60 frames a second.
+    private static final long UPLOAD_NANOS_PER_FRAME = 8_000_000L;
+    private static final double FACE_OVERLAP_PIXELS = 0.05D;
+
+    private static final String FACE_VERTEX_SHADER = """
+            #version 330 core
+            const int[6] CORNERS = int[6](0, 1, 2, 2, 1, 3);
+            uniform isamplerBuffer faces;
+            uniform int firstFace;
+            uniform mat4 toClip;
+            uniform ivec3 layerOrigin;
+            uniform vec3 centerFraction;
+            uniform int step;
+            uniform ivec3 normal;
+            uniform float overlap;
+            uniform int hiddenCells[%1$d];
+            uniform bool holeWall;
+            out vec2 units;
+            flat out ivec2 firstCell;
+            flat out int run;
+
+            bool hides(ivec2 column) {
+                if (any(lessThan(column, ivec2(0))) || any(greaterThanEqual(column, ivec2(%2$d)))) {
+                    return false;
+                }
+                int cell = column.y / %3$d * %4$d + column.x / %3$d;
+                return (hiddenCells[cell / 32] & (1 << (cell %% 32))) != 0;
+            }
+
+            // The same as TerrainHole.shows: no face of a hidden column, and beside the hole its wall instead of the
+            // usual side. No face crosses a cell's edge, so its first column decides for all of it.
+            bool showsWithHole(ivec2 column) {
+                if (hides(column)) {
+                    return false;
+                }
+                return normal.y == 1 || holeWall == hides(column + normal.xz);
+            }
+
+            // Corners are worked out in whole blocks relative to the view centre, so far from the world's origin
+            // nothing is lost to float precision. Faces meeting the middle of a longer face's edge leave hairline
+            // cracks along it, so every face reaches a little past its edges. Faces the hole leaves out land outside
+            // the view, where they're clipped away before any pixel is drawn.
+            void main() {
+                ivec4 face = texelFetch(faces, firstFace + gl_VertexID / 6);
+                if (!showsWithHole(face.xy)) {
+                    gl_Position = vec4(2.0, 2.0, 2.0, 1.0);
+                    units = vec2(0.0);
+                    firstCell = ivec2(0);
+                    run = 1;
+                    return;
+                }
+                int corner = CORNERS[gl_VertexID %% 6];
+                int alongRun = corner & 1;
+                int alongReach = corner >> 1;
+                run = face.w & 0xFFFF;
+                int reach = (face.w >> 16) & 0xFFFF;
+                bool runsAlongX = normal.x == 0;
+                bool isTop = normal.y == 1;
+                ivec3 origin = ivec3((face.x + max(normal.x, 0)) * step, face.z, (face.y + max(normal.z, 0)) * step);
+                ivec3 runEdge = runsAlongX ? ivec3(run * step, 0, 0) : ivec3(0, 0, run * step);
+                ivec3 reachEdge = isTop ? ivec3(0, 0, reach * step) : ivec3(0, reach, 0);
+                ivec3 position = layerOrigin + origin + alongRun * runEdge + alongReach * reachEdge;
+                vec3 runDirection = runsAlongX ? vec3(1.0, 0.0, 0.0) : vec3(0.0, 0.0, 1.0);
+                vec3 reachDirection = isTop ? vec3(0.0, 0.0, 1.0) : vec3(0.0, 1.0, 0.0);
+                vec3 outward = (float(alongRun) * 2.0 - 1.0) * runDirection + (float(alongReach) * 2.0 - 1.0) * reachDirection;
+                gl_Position = toClip * vec4(vec3(position) - centerFraction + outward * overlap, 1.0);
+                units = vec2(alongRun * run, alongReach * reach);
+                firstCell = face.xy;
+            }
+            """.formatted(TerrainHole.WORDS, TerrainTile.COLUMNS, TerrainHole.CELL_COLUMNS, TerrainHole.CELLS_ACROSS);
+
+    private static final String FACE_FRAGMENT_SHADER = """
+            #version 330 core
+            uniform sampler2D colors;
+            uniform ivec2 runDirection;
+            uniform float shade;
+            in vec2 units;
+            flat in ivec2 firstCell;
+            flat in int run;
+            out vec4 fragment;
+
+            float outlineStrength(float pixelsPerUnit) {
+                return clamp((pixelsPerUnit - %1$s) / (%2$s - %1$s), 0.0, 1.0);
+            }
+
+            float lineStrength(float along, float unitsPerPixel) {
+                float pixelsPerUnit = 1.0 / max(unitsPerPixel, 1e-6);
+                if (pixelsPerUnit < %1$s || abs(along - round(along)) * pixelsPerUnit >= %3$s) {
+                    return 0.0;
+                }
+                return outlineStrength(pixelsPerUnit);
+            }
+
+            void main() {
+                int along = clamp(int(floor(units.x)), 0, run - 1);
+                vec3 color = min(texelFetch(colors, firstCell + runDirection * along, 0).rgb * shade, vec3(1.0));
+                vec2 unitsPerPixel = fwidth(units);
+                float strength = lineStrength(units.x, unitsPerPixel.x);
+                if (strength == 0.0) {
+                    strength = lineStrength(units.y, unitsPerPixel.y);
+                }
+                float luminance = dot(color, vec3(0.3, 0.59, 0.11)) * 255.0;
+                vec3 outline = luminance < %4$s ? mix(color, vec3(1.0), %5$s) : color * %6$s;
+                fragment = vec4(mix(color, outline, strength), 1.0);
+            }
+            """.formatted(NoiseTerrainRenderer.LEAST_OUTLINE_SPACING_PIXELS, NoiseTerrainRenderer.FULL_OUTLINE_SPACING_PIXELS,
+            NoiseTerrainRenderer.OUTLINE_HALF_WIDTH_PIXELS, NoiseTerrainRenderer.DARK_LUMINANCE,
+            NoiseTerrainRenderer.OUTLINE_LIGHTENING, NoiseTerrainRenderer.OUTLINE_SHADE);
+
+    private static final String FLAT_VERTEX_SHADER = """
+            #version 330 core
+            uniform mat4 toClip;
+            uniform vec3 corner;
+            uniform vec3 edgeU;
+            uniform vec3 edgeV;
+
+            void main() {
+                float alongU = float(gl_VertexID & 1);
+                float alongV = float(gl_VertexID >> 1);
+                gl_Position = toClip * vec4(corner + alongU * edgeU + alongV * edgeV, 1.0);
+            }
+            """;
+
+    private static final String FLAT_FRAGMENT_SHADER = """
+            #version 330 core
+            uniform vec4 color;
+            out vec4 fragment;
+
+            void main() {
+                fragment = color;
+            }
+            """;
+
+    private static GpuTerrainRenderer onCard;
+
+    private final GpuProgram facesProgram = GpuProgram.of(FACE_VERTEX_SHADER, FACE_FRAGMENT_SHADER);
+    private final GpuProgram flatProgram = GpuProgram.of(FLAT_VERTEX_SHADER, FLAT_FRAGMENT_SHADER);
+    private final int attributelessVertexArray = glGenVertexArrays();
+    // Asked once: asking the card waits for everything sent to it so far.
+    private final int mostFacesPerLayer = glGetInteger(GL_MAX_TEXTURE_BUFFER_SIZE);
+    private final int largestColorsSide = glGetInteger(GL_MAX_TEXTURE_SIZE);
+    private final GpuTileCache uploadedTiles = new GpuTileCache();
+
+    /**
+     * @return the picture, or nothing when the card can't draw this scene and the caller should draw it without one
+     */
+    static Optional<OrbitPicture> render(NoiseTerrainScene scene, OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        return GpuFrames.drawPicture(target -> onCard().draw(scene, camera, width, height, coveredLeftWidth, target));
+    }
+
+    /**
+     * @return the frame, or nothing when it can't go straight into the window and the caller should draw a picture
+     */
+    static Optional<OrbitPicture> renderOnScreen(NoiseTerrainScene scene, ScreenTarget screen, OrbitCamera camera, int width, int height,
+                                                 int coveredLeftWidth) {
+        return GpuFrames.drawOnScreen(screen, target -> onCard().draw(scene, camera, width, height, coveredLeftWidth, target));
+    }
+
+    private static GpuTerrainRenderer onCard() {
+        if (onCard == null) {
+            onCard = new GpuTerrainRenderer();
+        }
+        return onCard;
+    }
+
+    /**
+     * Draws what of the scene is on the card. What isn't yet is put there over the next frames, as the picture asks to
+     * be drawn again, so turning the camera never waits on new ground being put on the card.
+     */
+    private Optional<OrbitPicture> draw(NoiseTerrainScene scene, OrbitCamera camera, int width, int height, int coveredLeftWidth,
+                                        GpuFrameTarget target) {
+        Uploads uploads = uploadWithinBudget(scene);
+        if (uploads == null) {
+            return Optional.empty();
+        }
+        OrbitPicture picture = drawLayers(scene, uploads.layers(), camera, width, height, coveredLeftWidth, target);
+        return Optional.of(uploads.complete() ? picture : picture.stillCatchingUp());
+    }
+
+    private OrbitPicture drawLayers(NoiseTerrainScene scene, List<UploadedLayer> layers, OrbitCamera camera, int width, int height,
+                                    int coveredLeftWidth, GpuFrameTarget target) {
+        OrbitProjection projection = scene.projection(camera, width, height, coveredLeftWidth);
+        NoiseTerrainScene.Extent extent = scene.extent();
+        double depthRange = extent.farthestFrom(projection.center()) + DEPTH_MARGIN_BLOCKS;
+        float[] toClip = projection.clipMatrix(width, height, depthRange);
+        target.bindSized(width, height);
+        GpuFrames.clearToBackground();
+        for (UploadedLayer layer : layers) {
+            drawFaces(layer, projection, toClip);
+        }
+        if (scene.hasWater()) {
+            drawWater(extent, BlockFaces.blockTop(scene.waterLevel()), projection, toClip);
+        }
+        GpuFrames.failOnError();
+        return target.finish(projection, depthRange);
+    }
+
+    /**
+     * Puts as many of the scene's layers on the card as fit in one frame's time, reusing what is already there, and
+     * says how to draw what is there. A place whose newest ground isn't on the card yet is drawn with what is, such as
+     * the ground from before the heights changed. Tiles the scene doesn't show stay on the card while they fit and are
+     * still in memory, as turning back to them is likely.
+     *
+     * @return the layers on the card, or null when one is too large for it
+     */
+    private Uploads uploadWithinBudget(NoiseTerrainScene scene) {
+        UploadProgress progress = uploadCoarsestFirst(scene.layers());
+        if (progress == UploadProgress.TOO_LARGE) {
+            return null;
+        }
+        List<UploadedLayer> layers = layersOnCard(scene.layers());
+        Set<GpuTileCache.Place> shown = new HashSet<>();
+        for (HoledLayer layer : scene.layers()) {
+            shown.add(GpuTileCache.Place.of(layer.terrain()));
+        }
+        uploadedTiles.forgetBeyond(MOST_UPLOADED_BYTES, shown);
+        return new Uploads(layers, progress == UploadProgress.COMPLETE);
+    }
+
+    // Coarse tiles cover the most ground for their upload, so they go first; finer ones then only cut their holes.
+    private UploadProgress uploadCoarsestFirst(List<HoledLayer> layers) {
+        long deadline = System.nanoTime() + UPLOAD_NANOS_PER_FRAME;
+        List<HoledLayer> coarsestFirst = new ArrayList<>(layers);
+        coarsestFirst.sort(Comparator.comparingInt((HoledLayer layer) -> layer.terrain().step()).reversed());
+        UploadProgress progress = UploadProgress.COMPLETE;
+        for (HoledLayer layer : coarsestFirst) {
+            GpuTileCache.Place place = GpuTileCache.Place.of(layer.terrain());
+            GpuTile tile = uploadedTiles.get(place);
+            if (tile != null && tile.shows(layer.layer())) {
+                continue;
+            }
+            if (System.nanoTime() > deadline) {
+                progress = UploadProgress.CATCHING_UP;
+                continue;
+            }
+            if (upload(layer.layer(), place, tile) == null) {
+                return UploadProgress.TOO_LARGE;
+            }
+        }
+        return progress;
+    }
+
+    // A hole is only cut where what fills it is on the card, so no ground is ever left out with nothing in its place.
+    // Tiles whose fillers are all on the card show nothing, so they aren't drawn at all.
+    private List<UploadedLayer> layersOnCard(List<HoledLayer> layers) {
+        List<UploadedLayer> onCard = new ArrayList<>(layers.size());
+        for (HoledLayer layer : layers) {
+            GpuTile tile = uploadedTiles.get(GpuTileCache.Place.of(layer.terrain()));
+            if (tile == null) {
+                continue;
+            }
+            TerrainHole hole = layer.holeAmong(filler -> uploadedTiles.get(GpuTileCache.Place.of(filler)) != null);
+            if (!hole.hidesAll()) {
+                onCard.add(new UploadedLayer(layer.terrain(), tile.faces(), tile.colors(), hole));
+            }
+        }
+        return onCard;
+    }
+
+    private GpuTile upload(TerrainLayer layer, GpuTileCache.Place place, GpuTile previous) {
+        if (previous != null) {
+            return previous.showInstead(layer, largestColorsSide, mostFacesPerLayer) ? previous : null;
+        }
+        GpuTile tile = GpuTile.upload(layer, largestColorsSide, mostFacesPerLayer);
+        if (tile != null) {
+            uploadedTiles.put(place, tile);
+        }
+        return tile;
+    }
+
+    // Faces looking away from the camera are hidden behind the ones looking toward it, so they're never drawn.
+    private void drawFaces(UploadedLayer layer, OrbitProjection projection, float[] toClip) {
+        Vec3 center = projection.center();
+        int wholeX = (int) Math.floor(center.x());
+        int wholeY = (int) Math.floor(center.y());
+        int wholeZ = (int) Math.floor(center.z());
+        facesProgram.use();
+        facesProgram.setMatrix("toClip", toClip);
+        facesProgram.set("colors", 0);
+        facesProgram.set("faces", 1);
+        facesProgram.set("layerOrigin", layer.terrain().originX() - wholeX, -wholeY, layer.terrain().originZ() - wholeZ);
+        facesProgram.set("centerFraction", new Vec3(center.x() - wholeX, center.y() - wholeY, center.z() - wholeZ));
+        facesProgram.set("step", layer.terrain().step());
+        facesProgram.set("overlap", FACE_OVERLAP_PIXELS / projection.pixelsPerBlock());
+        facesProgram.set("hiddenCells", layer.hole().hiddenCells());
+        glActiveTexture(GL_TEXTURE0);
+        layer.colors().bind();
+        glActiveTexture(GL_TEXTURE1);
+        layer.faces().bind();
+        glBindVertexArray(attributelessVertexArray);
+        for (BlockFaces.Kind kind : BlockFaces.Kind.values()) {
+            facesProgram.set("holeWall", kind == BlockFaces.Kind.HOLE_WALL ? 1 : 0);
+            for (BlockFaces.Facing facing : BlockFaces.Facing.values()) {
+                drawFacing(layer.faces(), kind, facing, projection);
+            }
+        }
+        glActiveTexture(GL_TEXTURE0);
+    }
+
+    private void drawFacing(GpuFaces faces, BlockFaces.Kind kind, BlockFaces.Facing facing, OrbitProjection projection) {
+        int count = faces.count(kind, facing);
+        if (count == 0 || !projection.facesCamera(facing.normalX, facing.normalY, facing.normalZ)) {
+            return;
+        }
+        facesProgram.set("firstFace", faces.first(kind, facing));
+        facesProgram.set("normal", facing.normalX, facing.normalY, facing.normalZ);
+        facesProgram.set("runDirection", facing.runsAlongX() ? 1 : 0, facing.runsAlongX() ? 0 : 1);
+        facesProgram.set("shade", NoiseTerrainRenderer.faceShadeAt(facing, projection.pixelsPerBlock()));
+        glDrawArrays(GL_TRIANGLES, 0, count * GpuFaces.CORNERS_PER_FACE);
+    }
+
+    // Water is blended over what lies below its surface, and hides nothing behind it. Ground level with the water's
+    // surface stays dry rather than flickering between the two.
+    private void drawWater(NoiseTerrainScene.Extent extent, int level, OrbitProjection projection, float[] toClip) {
+        glEnable(GL_BLEND);
+        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+        glDepthMask(false);
+        glEnable(GL_POLYGON_OFFSET_FILL);
+        glPolygonOffset(1F, 1F);
+        Vec3 center = projection.center();
+        flatProgram.use();
+        flatProgram.setMatrix("toClip", toClip);
+        flatProgram.set("corner", new Vec3(extent.minX() - center.x(), level - center.y(), extent.minZ() - center.z()));
+        flatProgram.set("edgeU", new Vec3(extent.sizeX(), 0D, 0D));
+        flatProgram.set("edgeV", new Vec3(0D, 0D, extent.sizeZ()));
+        int color = NoiseTerrainRenderer.WATER_COLOR;
+        flatProgram.set("color", GpuFrames.channel(color, 16), GpuFrames.channel(color, 8), GpuFrames.channel(color, 0),
+                NoiseTerrainRenderer.WATER_OPACITY);
+        glBindVertexArray(attributelessVertexArray);
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    }
+
+    private record Uploads(List<UploadedLayer> layers, boolean complete) {
+    }
+
+    private enum UploadProgress {
+        COMPLETE,
+        CATCHING_UP,
+        TOO_LARGE
+    }
+
+    private record UploadedLayer(NoiseTerrain terrain, GpuFaces faces, GpuColors colors, TerrainHole hole) {
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuTile.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 art.arcane.iris.studio.map;
+
+import java.lang.ref.WeakReference;
+
+/**
+ * A place on the ground on the graphics card: the colours and faces of the terrain last sampled there. They're put on
+ * the card once, whole, and stay as finer tiles inside come and go, since the face shader leaves out whatever hole they
+ * cut. When the noise or its heights change, the place is sampled anew; until the newest terrain is on the card, the
+ * older one still covers the place. Only for the GPU thread.
+ */
+final class GpuTile implements GpuCache.Upload {
+    private GpuColors colors;
+    private GpuFaces faces;
+    // Held weakly, so ground no longer drawn can be dropped from memory while its upload still stands in for it.
+    private WeakReference<TerrainLayer> source;
+
+    private GpuTile(GpuColors colors, GpuFaces faces, TerrainLayer source) {
+        this.colors = colors;
+        this.faces = faces;
+        this.source = new WeakReference<>(source);
+    }
+
+    /**
+     * @param largestSide the card's GL_MAX_TEXTURE_SIZE
+     * @param mostFaces   the card's GL_MAX_TEXTURE_BUFFER_SIZE
+     * @return the tile, or null when its terrain has more columns or rows than the card's textures can hold
+     */
+    static GpuTile upload(TerrainLayer layer, int largestSide, int mostFaces) {
+        GpuColors colors = GpuColors.upload(layer.terrain(), largestSide);
+        if (colors == null) {
+            return null;
+        }
+        try {
+            return new GpuTile(colors, GpuFaces.upload(layer.faces(), mostFaces), layer);
+        } catch (RuntimeException failure) {
+            colors.delete();
+            throw failure;
+        }
+    }
+
+    boolean shows(TerrainLayer wanted) {
+        return source.get() == wanted;
+    }
+
+    // Ground whose terrain is gone from memory is drawn only while nothing newer for its place is on the card.
+    boolean showsForgottenTerrain() {
+        return source.get() == null;
+    }
+
+    /**
+     * @return false when the layer's terrain has more columns or rows than the card's textures can hold
+     */
+    boolean showInstead(TerrainLayer wanted, int largestSide, int mostFaces) {
+        GpuTile next = upload(wanted, largestSide, mostFaces);
+        if (next == null) {
+            return false;
+        }
+        delete();
+        colors = next.colors;
+        faces = next.faces;
+        source = next.source;
+        return true;
+    }
+
+    GpuColors colors() {
+        return colors;
+    }
+
+    GpuFaces faces() {
+        return faces;
+    }
+
+    @Override
+    public long bytes() {
+        return colors.bytes() + faces.bytes();
+    }
+
+    @Override
+    public void delete() {
+        colors.delete();
+        faces.delete();
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuTileCache.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 art.arcane.iris.studio.map;
+
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * The ground on the graphics card by where it lies, so ground sampled anew for a place replaces what was there, which
+ * covers the place until then. Only for the GPU thread.
+ */
+final class GpuTileCache {
+    private final LinkedHashMap<Place, GpuTile> leastRecentlyUsedFirst = new LinkedHashMap<>(16, 0.75F, true);
+
+    GpuTile get(Place place) {
+        return leastRecentlyUsedFirst.get(place);
+    }
+
+    void put(Place place, GpuTile tile) {
+        leastRecentlyUsedFirst.put(place, tile);
+    }
+
+    /**
+     * Deletes ground not shown whose terrain is gone from memory, as it can never be drawn again, then the least
+     * recently used until the cache fits, sparing what is shown.
+     */
+    void forgetBeyond(long mostBytes, Set<Place> shown) {
+        long bytes = 0L;
+        Iterator<Map.Entry<Place, GpuTile>> oldestFirst = leastRecentlyUsedFirst.entrySet().iterator();
+        while (oldestFirst.hasNext()) {
+            Map.Entry<Place, GpuTile> entry = oldestFirst.next();
+            if (!shown.contains(entry.getKey()) && entry.getValue().showsForgottenTerrain()) {
+                entry.getValue().delete();
+                oldestFirst.remove();
+            } else {
+                bytes += entry.getValue().bytes();
+            }
+        }
+        oldestFirst = leastRecentlyUsedFirst.entrySet().iterator();
+        while (bytes > mostBytes && oldestFirst.hasNext()) {
+            Map.Entry<Place, GpuTile> entry = oldestFirst.next();
+            if (!shown.contains(entry.getKey())) {
+                bytes -= entry.getValue().bytes();
+                entry.getValue().delete();
+                oldestFirst.remove();
+            }
+        }
+    }
+
+    /**
+     * Where a tile's ground lies, and how coarse it is.
+     */
+    record Place(int originX, int originZ, int step) {
+        static Place of(NoiseTerrain terrain) {
+            return new Place(terrain.originX(), terrain.originZ(), terrain.step());
+        }
+
+        // The same place as the tile's terrain once sampled.
+        static Place of(TerrainTile tile) {
+            TerrainGrid grid = tile.grid();
+            return new Place(grid.originX(), grid.originZ(), grid.step());
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GpuWindowFrame.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 art.arcane.iris.studio.map;
+
+import java.awt.Rectangle;
+import java.awt.image.BufferedImage;
+import java.awt.image.DataBufferInt;
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.lwjgl.opengl.GL30.*;
+
+/**
+ * A frame drawn straight into a view's window. Of what was drawn, only the patches Swing paints where panels float
+ * over the window are read back. Only for the GPU thread.
+ */
+final class GpuWindowFrame implements GpuFrameTarget {
+    private static final int WINDOW_FRAMEBUFFER = 0;
+
+    private final GlxDisplay windows;
+    private final long window;
+    private final List<Rectangle> seeThrough;
+    private int width;
+    private int height;
+
+    /**
+     * @param seeThrough the parts of the view panels float over, which Swing paints instead of the window
+     */
+    GpuWindowFrame(GlxDisplay windows, long window, List<Rectangle> seeThrough) {
+        this.windows = windows;
+        this.window = window;
+        this.seeThrough = seeThrough;
+    }
+
+    // The context was first made current without any window, which left it drawing into no buffer; NVIDIA's driver
+    // keeps that once a window comes along.
+    @Override
+    public void bindSized(int nextWidth, int nextHeight) {
+        width = nextWidth;
+        height = nextHeight;
+        glBindFramebuffer(GL_FRAMEBUFFER, WINDOW_FRAMEBUFFER);
+        glDrawBuffer(GL_BACK);
+        glReadBuffer(GL_BACK);
+        glViewport(0, 0, width, height);
+    }
+
+    @Override
+    public OrbitPicture finish(OrbitProjection projection, double depthRange) {
+        OrbitPicture picture = OrbitPicture.onScreen(width, height, readPatches(),
+                GpuFrameTarget.depthInMiddle(projection, depthRange, width, height));
+        if (!windows.show(window)) {
+            throw new IllegalStateException("The window didn't take the frame");
+        }
+        return picture;
+    }
+
+    private List<PicturePatch> readPatches() {
+        Rectangle frame = new Rectangle(0, 0, width, height);
+        List<PicturePatch> patches = new ArrayList<>(seeThrough.size());
+        for (Rectangle part : seeThrough) {
+            Rectangle inFrame = part.intersection(frame);
+            if (!inFrame.isEmpty()) {
+                patches.add(read(inFrame));
+            }
+        }
+        return patches;
+    }
+
+    // Rows come bottom up.
+    private PicturePatch read(Rectangle area) {
+        int[] rows = new int[area.width * area.height];
+        glReadPixels(area.x, height - area.y - area.height, area.width, area.height, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, rows);
+        BufferedImage image = new BufferedImage(area.width, area.height, BufferedImage.TYPE_INT_RGB);
+        int[] pixels = ((DataBufferInt) image.getRaster().getDataBuffer()).getData();
+        for (int row = 0; row < area.height; row++) {
+            System.arraycopy(rows, (area.height - 1 - row) * area.width, pixels, row * area.width, area.width);
+        }
+        return new PicturePatch(area.x, area.y, image);
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/GroundSight.java

@@ -0,0 +1,130 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.function.DoubleBinaryOperator;
+
+/**
+ * How the 3D terrain view looks at the ground for one camera: which ground lies under a pixel, and which ground is on
+ * screen. The ground's height is asked for anew, so it holds wherever tiles are still coarse or missing.
+ *
+ * @param left   where the part of the view no panel floats over starts
+ * @param floorY the lowest the ground goes, as far as the view knows
+ * @param topY   the highest the ground goes, as far as the view knows
+ */
+record GroundSight(OrbitProjection projection, int left, int width, int height, int floorY, int topY) {
+    // Across the ground per step along a line of sight, so no column is stepped over.
+    private static final double MARCH_STEP_BLOCKS = 1D;
+    private static final int REFINE_STEPS = 10;
+
+    /**
+     * The ground drawn at a pixel: the first point down the line of sight that lies below the surface.
+     *
+     * @param surfaceY the ground's height at a spot, or the water's where that is higher
+     */
+    Optional<Vec3> groundAt(double screenX, double screenY, DoubleBinaryOperator surfaceY) {
+        double sinPitch = projection.towardCamera().y();
+        double stepY = MARCH_STEP_BLOCKS * sinPitch / Math.sqrt(Math.max(1E-6, 1D - sinPitch * sinPitch));
+        double aboveY = topY;
+        for (double y = topY; y >= floorY; y -= stepY) {
+            Vec3 point = projection.pointAt(screenX, screenY, y);
+            if (surfaceY.applyAsDouble(point.x(), point.z()) >= y) {
+                return Optional.of(refine(screenX, screenY, aboveY, y, surfaceY));
+            }
+            aboveY = y;
+        }
+        return Optional.empty();
+    }
+
+    // Halves the stretch of the line of sight where it passes into the ground until the point sits on the surface.
+    private Vec3 refine(double screenX, double screenY, double aboveY, double belowY, DoubleBinaryOperator surfaceY) {
+        double above = aboveY;
+        double below = belowY;
+        for (int step = 0; step < REFINE_STEPS; step++) {
+            double middle = (above + below) / 2D;
+            Vec3 point = projection.pointAt(screenX, screenY, middle);
+            if (surfaceY.applyAsDouble(point.x(), point.z()) >= middle) {
+                below = middle;
+            } else {
+                above = middle;
+            }
+        }
+        Vec3 point = projection.pointAt(screenX, screenY, below);
+        return new Vec3(point.x(), surfaceY.applyAsDouble(point.x(), point.z()), point.z());
+    }
+
+    /**
+     * Spots spread evenly over the ground on screen, about {@code most} of them over the stretch the view can reach. The
+     * view looks along parallel lines, so even on the ground is even on screen, but for slopes and hidden valleys. The
+     * spots keep to a grid fixed in the world, so turning the view a little doesn't change which spots are counted.
+     */
+    List<Vec3> groundInView(int most, DoubleBinaryOperator surfaceY) {
+        Reach reach = reach();
+        double spacing = gridSpacing(reach, most);
+        List<Vec3> spots = new ArrayList<>();
+        for (double z = Math.floor(reach.minZ() / spacing) * spacing; z <= reach.maxZ(); z += spacing) {
+            for (double x = Math.floor(reach.minX() / spacing) * spacing; x <= reach.maxX(); x += spacing) {
+                double y = surfaceY.applyAsDouble(x, z);
+                if (isOnScreen(x, y, z)) {
+                    spots.add(new Vec3(x, y, z));
+                }
+            }
+        }
+        return spots;
+    }
+
+    private boolean isOnScreen(double x, double y, double z) {
+        double screenX = projection.screenX(x, y, z);
+        double screenY = projection.screenY(x, y, z);
+        return screenX >= left && screenX < width && screenY >= 0D && screenY < height;
+    }
+
+    // The ground the view's corners look at, from the floor to the top.
+    private Reach reach() {
+        double minX = Double.POSITIVE_INFINITY;
+        double minZ = Double.POSITIVE_INFINITY;
+        double maxX = Double.NEGATIVE_INFINITY;
+        double maxZ = Double.NEGATIVE_INFINITY;
+        for (double screenX : new double[]{left, width}) {
+            for (double screenY : new double[]{0D, height}) {
+                for (double groundY : new double[]{floorY, topY}) {
+                    Vec3 point = projection.pointAt(screenX, screenY, groundY);
+                    minX = Math.min(minX, point.x());
+                    minZ = Math.min(minZ, point.z());
+                    maxX = Math.max(maxX, point.x());
+                    maxZ = Math.max(maxZ, point.z());
+                }
+            }
+        }
+        return new Reach(minX, minZ, maxX, maxZ);
+    }
+
+    // A whole power of two, so zooming only changes the grid when the spacing has doubled or halved.
+    private static double gridSpacing(Reach reach, int most) {
+        double area = Math.max(1D, (reach.maxX() - reach.minX()) * (reach.maxZ() - reach.minZ()));
+        double spacing = Math.sqrt(area / Math.max(1, most));
+        return Math.pow(2D, Math.ceil(Math.log(Math.max(1D, spacing)) / Math.log(2D)));
+    }
+
+    private record Reach(double minX, double minZ, double maxX, double maxZ) {
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/HoledLayer.java

@@ -0,0 +1,41 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.List;
+import java.util.function.Predicate;
+
+/**
+ * A tile's ground as the 3D noise view shows it, less the finer tiles inside it that are ready to fill their part. The
+ * hole is cut when drawing, from the fillers that are drawable by then, so ground is never left out before what fills
+ * it can be drawn.
+ */
+record HoledLayer(TerrainTile tile, TerrainLayer layer, List<TerrainTile> fillers) {
+    TerrainHole holeAmong(Predicate<TerrainTile> drawable) {
+        return TerrainHole.of(tile, fillers.stream().filter(drawable).toList());
+    }
+
+    TerrainHole holeOfAllFillers() {
+        return TerrainHole.of(tile, fillers);
+    }
+
+    NoiseTerrain terrain() {
+        return layer.terrain();
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/ImageMapExplorer.java

@@ -1,6 +1,5 @@
-package art.arcane.iris.studio.view;
+package art.arcane.iris.studio.map;
 
-import art.arcane.iris.configuration.IrisSettings;
 import art.arcane.iris.pack.loading.IrisData;
 import art.arcane.iris.localization.DesktopUiMessages;
 import art.arcane.iris.localization.IrisLanguage;
@@ -32,8 +31,8 @@ import javax.swing.DefaultCellEditor;
 import javax.swing.JButton;
 import javax.swing.JCheckBox;
 import javax.swing.JComboBox;
+import javax.swing.JComponent;
 import javax.swing.JFileChooser;
-import javax.swing.JFrame;
 import javax.swing.JLabel;
 import javax.swing.JPanel;
 import javax.swing.JScrollPane;
@@ -47,17 +46,13 @@ import javax.swing.filechooser.FileNameExtensionFilter;
 import javax.swing.table.DefaultTableModel;
 import java.awt.BorderLayout;
 import java.awt.CardLayout;
-import java.awt.Color;
 import java.awt.Component;
 import java.awt.Dimension;
-import java.awt.EventQueue;
 import java.awt.FlowLayout;
-import java.awt.Font;
 import java.awt.GridBagConstraints;
 import java.awt.GridBagLayout;
+import java.awt.GridLayout;
 import java.awt.Insets;
-import java.awt.event.WindowAdapter;
-import java.awt.event.WindowEvent;
 import java.io.File;
 import java.nio.file.Path;
 import java.util.ArrayList;
@@ -66,25 +61,23 @@ import java.util.List;
 import java.util.Objects;
 import java.util.function.DoubleBinaryOperator;
 
-public final class ImageMapStudioGUI {
-    private static final Color BACKGROUND = new Color(12, 15, 22);
-    private static final Color SIDEBAR_BACKGROUND = new Color(17, 20, 29);
-    private static final Color PANEL_BACKGROUND = new Color(23, 27, 38);
-    private static final Color FIELD_BACKGROUND = new Color(29, 34, 47);
-    private static final Color PRIMARY_TEXT = new Color(230, 234, 242);
-    private static final Color SECONDARY_TEXT = new Color(151, 160, 178);
-    private static final Color ACCENT = new Color(99, 161, 255);
-    private static final Color BORDER = new Color(48, 55, 72);
-    private static final Color ERROR = new Color(255, 116, 116);
-    private static final Color SUCCESS = new Color(91, 204, 139);
-    private static final Font BODY_FONT = new Font(Font.SANS_SERIF, Font.PLAIN, 12);
-    private static final Font LABEL_FONT = new Font(Font.SANS_SERIF, Font.BOLD, 11);
+/**
+ * The map window's Image maps view: turns a PNG into terrain height, biomes or a mask, previews it on the world and
+ * exports it into the pack.
+ */
+final class ImageMapExplorer {
+    private static final int EDITOR_WIDTH = 470;
+    private static final int OVERLAY_COLUMNS = 2;
+    private static final int TABLE_ROW_HEIGHT = 23;
+    private static final String STATUS_SEPARATOR = " · ";
 
     private final Engine engine;
     private final File packFolder;
     private final String dimensionKey;
-    private final JFrame frame;
     private final ImageMapStudioPreviewPanel previewPanel = new ImageMapStudioPreviewPanel();
+    private final StudioStatusBar statusBar = new StudioStatusBar();
+    private final List<JComponent> controls = new ArrayList<>();
+    private final JSplitPane view;
     private final JComboBox<String> presetPicker = new JComboBox<>();
     private final JTextField bindingKeyField = field("image-map");
     private final JTextField mapKeyField = field("image-map");
@@ -132,7 +125,6 @@ public final class ImageMapStudioGUI {
     private final JPanel typeCards = new JPanel(new CardLayout());
     private final JTextArea metadataArea = area(3);
     private final JTextArea diagnosticsArea = area(5);
-    private final JLabel statusLabel = new JLabel();
     private final JCheckBox chunksOverlay = selectedCheck();
     private final JCheckBox regionsOverlay = selectedCheck();
     private final JCheckBox boundaryOverlay = selectedCheck();
@@ -141,59 +133,60 @@ public final class ImageMapStudioGUI {
     private IrisWorldBoundary boundary;
     private boolean controlsUpdating;
 
-    private ImageMapStudioGUI(Engine engine) {
+    ImageMapExplorer(Engine engine) {
         this.engine = Objects.requireNonNull(engine, "Image Map Studio engine");
         this.packFolder = engine.getPackSource().toFile();
         this.dimensionKey = engine.getDimension().getLoadKey();
         this.boundary = engine.getDimension().getWorldBoundary() == null
                 ? null
                 : IrisWorldBoundary.snapshot(engine.getDimension().getWorldBoundary());
-        this.frame = new JFrame(text(DesktopUiMessages.IMAGEMAP_TITLE));
-        configureFrame();
+        buildControls();
+        this.view = buildWorkspace();
+        setStatus(DesktopUiMessages.IMAGEMAP_READY);
         configureControls();
         refreshPresets();
     }
 
-    public static boolean isAvailable() {
-        return GuiHost.isAvailable() && IrisSettings.get().getGui().isUseServerLaunchedGuis();
-    }
-
-    public static void launch(Engine engine) {
-        if (!GuiHost.isAvailable()) {
-            return;
-        }
-        EventQueue.invokeLater(() -> {
-            if (GuiHost.isAvailable()) {
-                new ImageMapStudioGUI(engine).show();
-            }
-        });
-    }
-
     static void reloadActiveEngine(Engine engine) {
         engine.hotloadSilently();
     }
 
-    private void configureFrame() {
-        GuiHost.prepareFrame(frame);
-        frame.getContentPane().setBackground(BACKGROUND);
-        frame.setLayout(new BorderLayout());
-        frame.add(buildToolbar(), BorderLayout.NORTH);
-        frame.add(buildWorkspace(), BorderLayout.CENTER);
-        frame.add(buildStatusBar(), BorderLayout.SOUTH);
-        frame.setSize(1540, 920);
-        frame.setMinimumSize(new Dimension(1040, 680));
-        frame.setLocationRelativeTo(null);
-        frame.addWindowListener(new WindowAdapter() {
-            @Override
-            public void windowClosed(WindowEvent event) {
-                previewPanel.close();
-            }
+    JComponent view() {
+        return view;
+    }
 
-            @Override
-            public void windowClosing(WindowEvent event) {
-                previewPanel.close();
-            }
-        });
+    JComponent statusBar() {
+        return statusBar;
+    }
+
+    /**
+     * Starts the editor right of the floating view list instead of under it.
+     */
+    void setCoveredLeftWidth(int width) {
+        view.setBorder(BorderFactory.createEmptyBorder(0, width, 0, 0));
+        view.setDividerLocation(width + StudioTheme.scale(EDITOR_WIDTH));
+        view.revalidate();
+    }
+
+    /**
+     * The toolbar buttons that belong to this view.
+     */
+    List<JComponent> controls() {
+        return controls;
+    }
+
+    /**
+     * Loads the first preset, once the view is on screen for the first time.
+     */
+    void open() {
+        String selected = (String) presetPicker.getSelectedItem();
+        if (selected != null && !selected.isBlank()) {
+            loadPreset(selected);
+        }
+    }
+
+    void close() {
+        previewPanel.close();
     }
 
     private void configureControls() {
@@ -214,90 +207,64 @@ public final class ImageMapStudioGUI {
         updateOverlays();
     }
 
-    private void show() {
-        frame.setVisible(true);
-        EventQueue.invokeLater(() -> {
-            String selected = (String) presetPicker.getSelectedItem();
-            if (selected != null && !selected.isBlank()) {
-                loadPreset(selected);
-            }
-        });
-    }
-
-    private JPanel buildToolbar() {
-        JPanel toolbar = new JPanel(new BorderLayout());
-        toolbar.setBackground(SIDEBAR_BACKGROUND);
-        toolbar.setBorder(BorderFactory.createMatteBorder(0, 0, 1, 0, BORDER));
-        JPanel leading = new JPanel(new FlowLayout(FlowLayout.LEFT, 7, 6));
-        leading.setOpaque(false);
-        JLabel presetLabel = label(DesktopUiMessages.IMAGEMAP_PRESET);
-        leading.add(presetLabel);
+    private void buildControls() {
         presetPicker.setPrototypeDisplayValue("terrain/example-long-preset");
-        styleCombo(presetPicker);
-        leading.add(presetPicker);
-        JButton load = button(DesktopUiMessages.IMAGEMAP_LOAD);
-        load.addActionListener(event -> {
+        presetPicker.setToolTipText("Image maps already in the pack");
+        presetPicker.setFocusable(false);
+        presetPicker.setMaximumSize(presetPicker.getPreferredSize());
+        controls.add(StudioToolbar.label(text(DesktopUiMessages.IMAGEMAP_PRESET)));
+        controls.add(presetPicker);
+        controls.add(StudioToolbar.button(text(DesktopUiMessages.IMAGEMAP_LOAD), "Load the chosen image map", () -> {
             String selected = (String) presetPicker.getSelectedItem();
             if (selected != null) {
                 loadPreset(selected);
             }
-        });
-        leading.add(load);
-        JButton importButton = button(DesktopUiMessages.IMAGEMAP_IMPORT_PNG);
-        importButton.addActionListener(event -> chooseSource(false));
-        leading.add(importButton);
-        JButton replaceButton = button(DesktopUiMessages.IMAGEMAP_REPLACE_PNG);
-        replaceButton.addActionListener(event -> chooseSource(true));
-        leading.add(replaceButton);
-        toolbar.add(leading, BorderLayout.WEST);
-
-        JPanel trailing = new JPanel(new FlowLayout(FlowLayout.RIGHT, 7, 6));
-        trailing.setOpaque(false);
-        JButton preview = button(DesktopUiMessages.IMAGEMAP_PREVIEW);
-        preview.addActionListener(event -> preview());
-        trailing.add(preview);
-        JButton export = button(DesktopUiMessages.IMAGEMAP_EXPORT);
-        export.setForeground(SUCCESS);
-        export.addActionListener(event -> export());
-        trailing.add(export);
-        toolbar.add(trailing, BorderLayout.EAST);
-        return toolbar;
+        }));
+        controls.add(StudioToolbar.button(text(DesktopUiMessages.IMAGEMAP_IMPORT_PNG), "Start a new image map from a PNG",
+                () -> chooseSource(false)));
+        controls.add(StudioToolbar.button(text(DesktopUiMessages.IMAGEMAP_REPLACE_PNG), "Swap the PNG behind this image map",
+                () -> chooseSource(true)));
+        controls.add(StudioToolbar.button(text(DesktopUiMessages.IMAGEMAP_PREVIEW), "Preview the image map on the world",
+                this::preview));
+        controls.add(StudioToolbar.button(text(DesktopUiMessages.IMAGEMAP_EXPORT), "Write the image map into the pack and hotload",
+                this::export));
     }
 
-    private Component buildWorkspace() {
+    private JSplitPane buildWorkspace() {
         JScrollPane editorScroll = new JScrollPane(buildEditor());
         editorScroll.setBorder(BorderFactory.createEmptyBorder());
-        editorScroll.getVerticalScrollBar().setUnitIncrement(18);
-        editorScroll.setPreferredSize(new Dimension(470, 760));
+        editorScroll.getVerticalScrollBar().setUnitIncrement(StudioTheme.scale(18));
+        editorScroll.setPreferredSize(StudioTheme.scaledSize(EDITOR_WIDTH, 760));
         JSplitPane split = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, editorScroll, previewPanel);
         split.setBorder(BorderFactory.createEmptyBorder());
-        split.setDividerSize(5);
         split.setResizeWeight(0D);
-        split.setDividerLocation(470);
+        split.setDividerLocation(StudioTheme.scale(EDITOR_WIDTH));
+        split.putClientProperty("FlatLaf.style", "style: grip");
         return split;
     }
 
     private JPanel buildEditor() {
-        JPanel editor = new JPanel();
+        JPanel editor = new ViewportWidthPanel();
         editor.setLayout(new BoxLayout(editor, BoxLayout.Y_AXIS));
-        editor.setBackground(SIDEBAR_BACKGROUND);
-        editor.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
+        editor.setBackground(StudioTheme.PANEL_BACKGROUND);
+        editor.setBorder(StudioTheme.emptyBorder(10, 10, 10, 10));
         editor.add(section(DesktopUiMessages.IMAGEMAP_METADATA, metadataPanel()));
-        editor.add(Box.createVerticalStrut(9));
+        editor.add(Box.createVerticalStrut(StudioTheme.scale(9)));
         editor.add(section(DesktopUiMessages.IMAGEMAP_RESOURCE, resourcePanel()));
-        editor.add(Box.createVerticalStrut(9));
+        editor.add(Box.createVerticalStrut(StudioTheme.scale(9)));
         editor.add(section(DesktopUiMessages.IMAGEMAP_COORDINATES, coordinatePanel()));
-        editor.add(Box.createVerticalStrut(9));
+        editor.add(Box.createVerticalStrut(StudioTheme.scale(9)));
         typeCards.add(heightPanel(), "HEIGHT");
         typeCards.add(colorPanel(), "COLOR");
         typeCards.add(maskPanel(), "MASK");
-        typeCards.setBackground(SIDEBAR_BACKGROUND);
+        typeCards.setOpaque(false);
+        typeCards.setAlignmentX(Component.LEFT_ALIGNMENT);
         editor.add(typeCards);
-        editor.add(Box.createVerticalStrut(9));
+        editor.add(Box.createVerticalStrut(StudioTheme.scale(9)));
         editor.add(section(DesktopUiMessages.IMAGEMAP_COMPOSED_MASKS, composedMaskPanel()));
-        editor.add(Box.createVerticalStrut(9));
+        editor.add(Box.createVerticalStrut(StudioTheme.scale(9)));
         editor.add(section(DesktopUiMessages.IMAGEMAP_OVERLAYS, overlayPanel()));
-        editor.add(Box.createVerticalStrut(9));
+        editor.add(Box.createVerticalStrut(StudioTheme.scale(9)));
         editor.add(section(DesktopUiMessages.IMAGEMAP_DIAGNOSTICS, diagnosticsPanel()));
         return editor;
     }
@@ -358,18 +325,15 @@ public final class ImageMapStudioGUI {
     }
 
     private JPanel colorPanel() {
-        JPanel panel = new JPanel(new BorderLayout(0, 7));
+        JPanel panel = new JPanel(new BorderLayout(0, StudioTheme.scale(7)));
         panel.setOpaque(false);
         JPanel settings = form();
         addRow(settings, 0, DesktopUiMessages.IMAGEMAP_COLOR_TOLERANCE, toleranceField);
         addRow(settings, 1, DesktopUiMessages.IMAGEMAP_UNKNOWN_COLOR, unknownColorPicker);
         panel.add(settings, BorderLayout.NORTH);
-        configureLegendTable();
-        JScrollPane scroll = new JScrollPane(legendTable);
-        scroll.setPreferredSize(new Dimension(390, 160));
-        scroll.setBorder(BorderFactory.createLineBorder(BORDER));
-        panel.add(scroll, BorderLayout.CENTER);
-        JPanel actions = new JPanel(new FlowLayout(FlowLayout.LEFT, 6, 0));
+        configureTable(legendTable);
+        panel.add(tableScroll(legendTable, 160), BorderLayout.CENTER);
+        JPanel actions = new JPanel(new FlowLayout(FlowLayout.LEFT, StudioTheme.scale(6), 0));
         actions.setOpaque(false);
         JButton add = button(DesktopUiMessages.IMAGEMAP_ADD_COLOR);
         add.addActionListener(event -> legendModel.addRow(new Object[]{"#000000", "iris:"}));
@@ -382,7 +346,7 @@ public final class ImageMapStudioGUI {
     }
 
     private JPanel overlayPanel() {
-        JPanel panel = new JPanel(new FlowLayout(FlowLayout.LEFT, 9, 2));
+        JPanel panel = new JPanel(new GridLayout(0, OVERLAY_COLUMNS, StudioTheme.scale(9), StudioTheme.scale(2)));
         panel.setOpaque(false);
         chunksOverlay.setText(text(DesktopUiMessages.IMAGEMAP_CHUNKS));
         regionsOverlay.setText(text(DesktopUiMessages.IMAGEMAP_REGIONS));
@@ -396,13 +360,10 @@ public final class ImageMapStudioGUI {
     }
 
     private JPanel composedMaskPanel() {
-        JPanel panel = new JPanel(new BorderLayout(0, 7));
+        JPanel panel = new JPanel(new BorderLayout(0, StudioTheme.scale(7)));
         panel.setOpaque(false);
-        JScrollPane scroll = new JScrollPane(composedMaskTable);
-        scroll.setPreferredSize(new Dimension(390, 120));
-        scroll.setBorder(BorderFactory.createLineBorder(BORDER));
-        panel.add(scroll, BorderLayout.CENTER);
-        JPanel actions = new JPanel(new FlowLayout(FlowLayout.LEFT, 6, 0));
+        panel.add(tableScroll(composedMaskTable, 120), BorderLayout.CENTER);
+        JPanel actions = new JPanel(new FlowLayout(FlowLayout.LEFT, StudioTheme.scale(6), 0));
         actions.setOpaque(false);
         JButton add = button(DesktopUiMessages.IMAGEMAP_ADD_MASK);
         add.addActionListener(event -> composedMaskModel.addRow(new Object[]{
@@ -421,21 +382,6 @@ public final class ImageMapStudioGUI {
         return single(diagnosticsArea);
     }
 
-    private JPanel buildStatusBar() {
-        JPanel panel = new JPanel(new BorderLayout());
-        panel.setBackground(PANEL_BACKGROUND);
-        panel.setBorder(BorderFactory.createCompoundBorder(
-                BorderFactory.createMatteBorder(1, 0, 0, 0, BORDER),
-                BorderFactory.createEmptyBorder(5, 9, 5, 9)
-        ));
-        statusLabel.setForeground(SECONDARY_TEXT);
-        statusLabel.setFont(BODY_FONT);
-        statusLabel.setText(packFolder.getName() + "  |  " + dimensionKey + "  |  "
-                + text(DesktopUiMessages.IMAGEMAP_READY));
-        panel.add(statusLabel, BorderLayout.WEST);
-        return panel;
-    }
-
     private void refreshPresets() {
         IrisData data = IrisData.openRuntime(packFolder);
         try {
@@ -518,7 +464,7 @@ public final class ImageMapStudioGUI {
                 ? DesktopUiMessages.IMAGEMAP_REPLACE_PNG
                 : DesktopUiMessages.IMAGEMAP_IMPORT_PNG));
         chooser.setFileFilter(new FileNameExtensionFilter("PNG", "png"));
-        if (chooser.showOpenDialog(frame) != JFileChooser.APPROVE_OPTION) {
+        if (chooser.showOpenDialog(view) != JFileChooser.APPROVE_OPTION) {
             return;
         }
         sourcePath = chooser.getSelectedFile().toPath().toAbsolutePath().normalize();
@@ -626,7 +572,7 @@ public final class ImageMapStudioGUI {
                     diagnosticsArea.setText(warnings.isEmpty()
                             ? text(DesktopUiMessages.IMAGEMAP_PREVIEW_VALID)
                             : String.join("\n", warnings));
-                    diagnosticsArea.setForeground(warnings.isEmpty() ? SUCCESS : PRIMARY_TEXT);
+                    diagnosticsArea.setForeground(warnings.isEmpty() ? StudioTheme.SUCCESS : StudioTheme.TEXT);
                     setStatus(DesktopUiMessages.IMAGEMAP_READY);
                 } catch (Exception exception) {
                     showFailure(text(DesktopUiMessages.IMAGEMAP_PREVIEW_FAILED), exception);
@@ -682,7 +628,7 @@ public final class ImageMapStudioGUI {
                     for (String warning : result.warnings()) {
                         message.append('\n').append(warning);
                     }
-                    diagnosticsArea.setForeground(SUCCESS);
+                    diagnosticsArea.setForeground(StudioTheme.SUCCESS);
                     diagnosticsArea.setText(message.toString());
                     setStatus(DesktopUiMessages.IMAGEMAP_EXPORTED);
                     refreshPresets();
@@ -853,35 +799,25 @@ public final class ImageMapStudioGUI {
         );
     }
 
-    private void configureLegendTable() {
-        legendTable.setBackground(FIELD_BACKGROUND);
-        legendTable.setForeground(PRIMARY_TEXT);
-        legendTable.setGridColor(BORDER);
-        legendTable.setSelectionBackground(new Color(42, 55, 78));
-        legendTable.setSelectionForeground(PRIMARY_TEXT);
-        legendTable.setFont(BODY_FONT);
-        legendTable.setRowHeight(23);
-        legendTable.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
-        legendTable.getTableHeader().setBackground(PANEL_BACKGROUND);
-        legendTable.getTableHeader().setForeground(PRIMARY_TEXT);
+    private static void configureTable(JTable table) {
+        table.setRowHeight(StudioTheme.scale(TABLE_ROW_HEIGHT));
+        table.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
     }
 
     private void configureComposedMaskTable() {
-        composedMaskTable.setBackground(FIELD_BACKGROUND);
-        composedMaskTable.setForeground(PRIMARY_TEXT);
-        composedMaskTable.setGridColor(BORDER);
-        composedMaskTable.setSelectionBackground(new Color(42, 55, 78));
-        composedMaskTable.setSelectionForeground(PRIMARY_TEXT);
-        composedMaskTable.setFont(BODY_FONT);
-        composedMaskTable.setRowHeight(23);
-        composedMaskTable.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
-        composedMaskTable.getTableHeader().setBackground(PANEL_BACKGROUND);
-        composedMaskTable.getTableHeader().setForeground(PRIMARY_TEXT);
+        configureTable(composedMaskTable);
         composedMaskTable.getColumnModel().getColumn(1).setCellEditor(
                 new DefaultCellEditor(new JComboBox<>(IrisImageMapMaskOperation.values()))
         );
     }
 
+    private static JScrollPane tableScroll(JTable table, int height) {
+        JScrollPane scroll = new JScrollPane(table);
+        scroll.setPreferredSize(StudioTheme.scaledSize(390, height));
+        scroll.setBorder(BorderFactory.createLineBorder(StudioTheme.CONTROL_BORDER));
+        return scroll;
+    }
+
     private void removeLegendRows() {
         removeRows(legendTable, legendModel);
     }
@@ -927,7 +863,7 @@ public final class ImageMapStudioGUI {
             return;
         }
         String current = diagnosticsArea.getText();
-        diagnosticsArea.setForeground(ERROR);
+        diagnosticsArea.setForeground(StudioTheme.ERROR);
         diagnosticsArea.setText(current.isBlank() ? diagnostic : current + "\n" + diagnostic);
     }
 
@@ -939,13 +875,13 @@ public final class ImageMapStudioGUI {
         if (!(cause instanceof IllegalArgumentException)) {
             IrisLogging.reportError(cause);
         }
-        diagnosticsArea.setForeground(ERROR);
+        diagnosticsArea.setForeground(StudioTheme.ERROR);
         diagnosticsArea.setText(prefix + ": " + String.valueOf(cause.getMessage()));
-        statusLabel.setText(prefix);
+        statusBar.showError(prefix);
     }
 
     private void setStatus(TextKey key) {
-        statusLabel.setText(packFolder.getName() + "  |  " + dimensionKey + "  |  " + text(key));
+        statusBar.showSummary(packFolder.getName() + STATUS_SEPARATOR + dimensionKey + STATUS_SEPARATOR + text(key));
     }
 
     private void requireSource() {
@@ -961,42 +897,41 @@ public final class ImageMapStudioGUI {
     }
 
     private static void addRow(JPanel panel, int row, TextKey key, Component component) {
+        int rowGap = StudioTheme.scale(3);
         GridBagConstraints labelConstraints = new GridBagConstraints();
         labelConstraints.gridx = 0;
         labelConstraints.gridy = row;
         labelConstraints.anchor = GridBagConstraints.WEST;
-        labelConstraints.insets = new Insets(3, 0, 3, 8);
-        JLabel label = label(key);
-        panel.add(label, labelConstraints);
+        labelConstraints.insets = new Insets(rowGap, 0, rowGap, StudioTheme.scale(8));
+        panel.add(label(key), labelConstraints);
 
         GridBagConstraints componentConstraints = new GridBagConstraints();
         componentConstraints.gridx = 1;
         componentConstraints.gridy = row;
         componentConstraints.weightx = 1D;
         componentConstraints.fill = GridBagConstraints.HORIZONTAL;
-        componentConstraints.insets = new Insets(3, 0, 3, 0);
+        componentConstraints.insets = new Insets(rowGap, 0, rowGap, 0);
         panel.add(component, componentConstraints);
     }
 
     private static JPanel section(TextKey title, Component content) {
         JPanel panel = new JPanel(new BorderLayout());
         panel.setAlignmentX(Component.LEFT_ALIGNMENT);
-        panel.setBackground(PANEL_BACKGROUND);
-        panel.setBorder(BorderFactory.createLineBorder(BORDER));
+        panel.setOpaque(false);
+        panel.setBorder(BorderFactory.createLineBorder(StudioTheme.CONTROL_BORDER));
         JLabel heading = new JLabel(text(title));
-        heading.setForeground(PRIMARY_TEXT);
-        heading.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 12));
+        heading.setFont(StudioTheme.sectionFont());
         heading.setBorder(BorderFactory.createCompoundBorder(
-                BorderFactory.createMatteBorder(0, 0, 1, 0, BORDER),
-                BorderFactory.createEmptyBorder(7, 9, 7, 9)
+                BorderFactory.createMatteBorder(0, 0, 1, 0, StudioTheme.CONTROL_BORDER),
+                StudioTheme.emptyBorder(7, 9, 7, 9)
         ));
         panel.add(heading, BorderLayout.NORTH);
         JPanel body = new JPanel(new BorderLayout());
         body.setOpaque(false);
-        body.setBorder(BorderFactory.createEmptyBorder(8, 9, 9, 9));
+        body.setBorder(StudioTheme.emptyBorder(8, 9, 9, 9));
         body.add(content, BorderLayout.CENTER);
         panel.add(body, BorderLayout.CENTER);
-        panel.setMaximumSize(new Dimension(Integer.MAX_VALUE, panel.getPreferredSize().height + 300));
+        panel.setMaximumSize(new Dimension(Integer.MAX_VALUE, panel.getPreferredSize().height + StudioTheme.scale(300)));
         return panel;
     }
 
@@ -1009,34 +944,19 @@ public final class ImageMapStudioGUI {
 
     private static JLabel label(TextKey key) {
         JLabel label = new JLabel(text(key));
-        label.setForeground(SECONDARY_TEXT);
-        label.setFont(LABEL_FONT);
+        label.setForeground(StudioTheme.SECONDARY_TEXT);
+        label.setFont(StudioTheme.smallFont());
         return label;
     }
 
     private static JButton button(TextKey key) {
         JButton button = new JButton(text(key));
-        button.setBackground(FIELD_BACKGROUND);
-        button.setForeground(PRIMARY_TEXT);
-        button.setFocusPainted(false);
-        button.setBorder(BorderFactory.createCompoundBorder(
-                BorderFactory.createLineBorder(BORDER),
-                BorderFactory.createEmptyBorder(5, 9, 5, 9)
-        ));
+        button.setFocusable(false);
         return button;
     }
 
     private static JTextField field(String value) {
-        JTextField field = new JTextField(value);
-        field.setBackground(FIELD_BACKGROUND);
-        field.setForeground(PRIMARY_TEXT);
-        field.setCaretColor(PRIMARY_TEXT);
-        field.setFont(BODY_FONT);
-        field.setBorder(BorderFactory.createCompoundBorder(
-                BorderFactory.createLineBorder(BORDER),
-                BorderFactory.createEmptyBorder(5, 7, 5, 7)
-        ));
-        return field;
+        return new JTextField(value);
     }
 
     private static JTextArea area(int rows) {
@@ -1044,18 +964,14 @@ public final class ImageMapStudioGUI {
         area.setEditable(false);
         area.setLineWrap(true);
         area.setWrapStyleWord(true);
-        area.setBackground(FIELD_BACKGROUND);
-        area.setForeground(PRIMARY_TEXT);
-        area.setFont(BODY_FONT);
-        area.setBorder(BorderFactory.createEmptyBorder(6, 7, 6, 7));
+        area.setBorder(StudioTheme.emptyBorder(6, 7, 6, 7));
         return area;
     }
 
     private static JCheckBox check() {
         JCheckBox check = new JCheckBox();
         check.setOpaque(false);
-        check.setForeground(PRIMARY_TEXT);
-        check.setFocusPainted(false);
+        check.setFocusable(false);
         return check;
     }
 
@@ -1067,15 +983,8 @@ public final class ImageMapStudioGUI {
 
     private static <T> JComboBox<T> combo(T[] values) {
         JComboBox<T> combo = new JComboBox<>(values);
-        styleCombo(combo);
-        return combo;
-    }
-
-    private static void styleCombo(JComboBox<?> combo) {
-        combo.setBackground(FIELD_BACKGROUND);
-        combo.setForeground(PRIMARY_TEXT);
-        combo.setFont(BODY_FONT);
         combo.setFocusable(false);
+        return combo;
     }
 
     private static double number(JTextField field, String name) {

core/src/main/java/art/arcane/iris/studio/map/ImageMapStudioModel.java

@@ -1,4 +1,4 @@
-package art.arcane.iris.studio.view;
+package art.arcane.iris.studio.map;
 
 import art.arcane.iris.generation.image.IrisImage;
 import art.arcane.iris.generation.image.IrisImageMap;

core/src/main/java/art/arcane/iris/studio/map/ImageMapStudioPreviewPanel.java

@@ -1,4 +1,4 @@
-package art.arcane.iris.studio.view;
+package art.arcane.iris.studio.map;
 
 import art.arcane.iris.localization.DesktopUiMessages;
 import art.arcane.iris.localization.IrisLanguage;
@@ -40,11 +40,9 @@ import java.util.function.Consumer;
 import java.util.function.DoubleBinaryOperator;
 
 final class ImageMapStudioPreviewPanel extends JPanel implements AutoCloseable {
-    private static final Color BACKGROUND = new Color(12, 15, 22);
-    private static final Color PANEL_BACKGROUND = new Color(20, 24, 33);
-    private static final Color BORDER = new Color(48, 55, 72);
-    private static final Color TEXT = new Color(230, 234, 242);
-    private static final Color SECONDARY = new Color(151, 160, 178);
+    // The images and their overlay lines are drawn for a dark backdrop, in either theme.
+    private static final Color CANVAS_BACKGROUND = new Color(12, 15, 22);
+    private static final Color CANVAS_TEXT = new Color(151, 160, 178);
 
     private final SourceCanvas sourceCanvas = new SourceCanvas();
     private final WorldCanvas worldCanvas = new WorldCanvas();
@@ -52,21 +50,19 @@ final class ImageMapStudioPreviewPanel extends JPanel implements AutoCloseable {
 
     ImageMapStudioPreviewPanel() {
         super(new BorderLayout());
-        setBackground(BACKGROUND);
+        setBackground(StudioTheme.PANEL_BACKGROUND);
         JPanel source = wrap(IrisLanguage.plain(DesktopUiMessages.IMAGEMAP_SOURCE), sourceCanvas);
         JPanel interpreted = wrap(IrisLanguage.plain(DesktopUiMessages.IMAGEMAP_INTERPRETED), worldCanvas);
         JSplitPane split = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, source, interpreted);
         split.setBorder(BorderFactory.createEmptyBorder());
-        split.setDividerSize(5);
         split.setResizeWeight(0.42D);
-        split.setBackground(BACKGROUND);
+        split.putClientProperty("FlatLaf.style", "style: grip");
         add(split, BorderLayout.CENTER);
-        statusLabel.setForeground(SECONDARY);
-        statusLabel.setBackground(PANEL_BACKGROUND);
-        statusLabel.setOpaque(true);
+        statusLabel.setForeground(StudioTheme.SECONDARY_TEXT);
+        statusLabel.setFont(StudioTheme.smallFont());
         statusLabel.setBorder(BorderFactory.createCompoundBorder(
-                BorderFactory.createMatteBorder(1, 0, 0, 0, BORDER),
-                BorderFactory.createEmptyBorder(5, 9, 5, 9)
+                BorderFactory.createMatteBorder(1, 0, 0, 0, StudioTheme.SEPARATOR),
+                StudioTheme.emptyBorder(5, 9, 5, 9)
         ));
         add(statusLabel, BorderLayout.SOUTH);
         worldCanvas.setHoverConsumer(statusLabel::setText);
@@ -123,15 +119,13 @@ final class ImageMapStudioPreviewPanel extends JPanel implements AutoCloseable {
 
     private static JPanel wrap(String title, JPanel canvas) {
         JPanel panel = new JPanel(new BorderLayout());
-        panel.setBackground(PANEL_BACKGROUND);
-        panel.setBorder(BorderFactory.createLineBorder(BORDER));
+        panel.setOpaque(false);
+        panel.setBorder(BorderFactory.createLineBorder(StudioTheme.SEPARATOR));
         JLabel label = new JLabel(title);
-        label.setForeground(TEXT);
-        label.setBackground(PANEL_BACKGROUND);
-        label.setOpaque(true);
+        label.setFont(StudioTheme.sectionFont());
         label.setBorder(BorderFactory.createCompoundBorder(
-                BorderFactory.createMatteBorder(0, 0, 1, 0, BORDER),
-                BorderFactory.createEmptyBorder(6, 9, 6, 9)
+                BorderFactory.createMatteBorder(0, 0, 1, 0, StudioTheme.SEPARATOR),
+                StudioTheme.emptyBorder(6, 9, 6, 9)
         ));
         panel.add(label, BorderLayout.NORTH);
         panel.add(canvas, BorderLayout.CENTER);
@@ -142,7 +136,7 @@ final class ImageMapStudioPreviewPanel extends JPanel implements AutoCloseable {
         private BufferedImage source;
 
         private SourceCanvas() {
-            setBackground(BACKGROUND);
+            setBackground(CANVAS_BACKGROUND);
             setPreferredSize(new Dimension(420, 520));
         }
 
@@ -217,7 +211,7 @@ final class ImageMapStudioPreviewPanel extends JPanel implements AutoCloseable {
         private double dragCenterZ;
 
         private WorldCanvas() {
-            setBackground(BACKGROUND);
+            setBackground(CANVAS_BACKGROUND);
             setPreferredSize(new Dimension(620, 520));
             MouseAdapter mouse = new MouseAdapter() {
                 @Override
@@ -414,7 +408,7 @@ final class ImageMapStudioPreviewPanel extends JPanel implements AutoCloseable {
                             );
                             case COLOR_MAP -> categoricalApplication()
                                     && !IrisImageMapRuntime.selectCategorical(maskWeight)
-                                    ? BACKGROUND.getRGB()
+                                    ? CANVAS_BACKGROUND.getRGB()
                                     : ImageMapStudioModel.targetColor(compiled.sampleTarget(worldX, worldZ));
                             case BINARY_MASK, GRAYSCALE_MASK, ALPHA_MASK -> grayscale(
                                     compiled.sampleNormalized(worldX, worldZ)
@@ -603,7 +597,7 @@ final class ImageMapStudioPreviewPanel extends JPanel implements AutoCloseable {
     private static void drawEmpty(Graphics graphics, String text) {
         Graphics2D canvas = (Graphics2D) graphics.create();
         try {
-            canvas.setColor(SECONDARY);
+            canvas.setColor(CANVAS_TEXT);
             canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
             int width = canvas.getFontMetrics().stringWidth(text);
             int x = Math.max(8, (graphics.getClipBounds() == null ? 0 : graphics.getClipBounds().width - width) / 2);

core/src/main/java/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/IslandPanel.java

@@ -0,0 +1,93 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import javax.swing.JComponent;
+import javax.swing.JPanel;
+import java.awt.BorderLayout;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Rectangle;
+import java.awt.RenderingHints;
+import java.awt.geom.RoundRectangle2D;
+import java.util.List;
+
+/**
+ * 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 implements FloatingPanels.PartlySeeThrough {
+    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);
+    }
+
+    // The gap all around, reaching in as far as the rounded corners do.
+    @Override
+    public List<Rectangle> seeThroughParts() {
+        int width = getWidth();
+        int height = getHeight();
+        int gap = StudioTheme.scale(GAP);
+        int edge = gap + (int) Math.ceil(StudioTheme.scale((double) CORNER_ARC) / 2D);
+        return List.of(
+                new Rectangle(0, 0, width, edge),
+                new Rectangle(0, height - edge, width, edge),
+                new Rectangle(0, edge, gap, height - edge * 2),
+                new Rectangle(width - gap, edge, gap, height - edge * 2));
+    }
+
+    @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/art/arcane/iris/studio/map/LatestMeasurement.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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.spi.IrisLogging;
+
+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.BooleanSupplier;
+import java.util.function.Consumer;
+import java.util.function.Function;
+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) {
+        measureUntilSuperseded(stillWanted -> measurement.get(), show);
+    }
+
+    /**
+     * Like {@link #measure}, for long measurements that ask {@code stillWanted} between steps and give up once another
+     * measurement was asked for.
+     */
+    void measureUntilSuperseded(Function<BooleanSupplier, T> measurement, Consumer<T> show) {
+        long requested = generation.incrementAndGet();
+        BooleanSupplier stillWanted = () -> requested == generation.get();
+        worker.execute(() -> {
+            T result = measureSafely(() -> measurement.apply(stillWanted));
+            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) {
+            IrisLogging.reportError(error);
+            return null;
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/LoadingAnimation.java

@@ -0,0 +1,159 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+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, and once it shows it
+ * stays for {@link #SHOW_AT_LEAST_MILLIS}, so it never flashes.
+ */
+final class LoadingAnimation {
+    static final int SHOW_AFTER_MILLIS = 300;
+    static final int SHOW_AT_LEAST_MILLIS = 700;
+    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;
+    }
+
+    /**
+     * How much longer the animation of a load that began at {@code loadingSinceMillis} has to stay up once the load is
+     * done; zero when it never showed or has shown long enough.
+     */
+    static long remainingShowMillis(long loadingSinceMillis) {
+        if (!isDue(loadingSinceMillis)) {
+            return 0L;
+        }
+        long shownMillis = System.currentTimeMillis() - loadingSinceMillis - SHOW_AFTER_MILLIS;
+        return Math.max(0L, SHOW_AT_LEAST_MILLIS - shownMillis);
+    }
+
+    /**
+     * 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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.components.MapLabels;
+import art.arcane.iris.studio.map.components.MapStyle;
+import art.arcane.iris.studio.map.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/art/arcane/iris/studio/map/MapHost.java

@@ -0,0 +1,122 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.generation.runtime.Engine;
+import art.arcane.iris.generation.runtime.PreservationRegistry;
+import art.arcane.iris.spi.IrisServices;
+import art.arcane.iris.studio.view.GuiHost;
+import art.arcane.iris.studio.view.GuiOverlay;
+
+import javax.swing.JFrame;
+import java.awt.Dimension;
+import java.awt.GraphicsEnvironment;
+import java.awt.Rectangle;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
+import java.awt.image.BufferedImage;
+import java.util.UUID;
+import java.util.concurrent.ExecutorService;
+
+/**
+ * What the studio windows need from the server they run in: frames it closes on shutdown, engines and hotload
+ * notices from the platform's {@link GuiHost.Provider}, and threads it stops with the plugin.
+ */
+public final class MapHost {
+    private MapHost() {
+    }
+
+    static boolean isAvailable() {
+        return GuiHost.isAvailable();
+    }
+
+    static JFrame createFrame(String title) {
+        XwaylandWindowManagerHint.apply();
+        StudioTheme.install();
+        JFrame frame = new JFrame(title);
+        GuiHost.prepareFrame(frame);
+        frame.addWindowListener(new WindowAdapter() {
+            @Override
+            public void windowActivated(WindowEvent event) {
+                StudioTheme.followSystem();
+            }
+        });
+        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));
+    }
+
+    static Engine findActiveEngine() {
+        return usable(GuiHost.get().findActiveEngine());
+    }
+
+    /**
+     * The engine of the world the window was opened for, or the active one on platforms that can't look worlds up.
+     */
+    static Engine findEngine(UUID worldId) {
+        Engine engine = worldId == null ? null : usable(GuiHost.get().findEngine(worldId));
+        return engine != null ? engine : findActiveEngine();
+    }
+
+    static GuiOverlay overlayFor(Engine engine, UUID openerId) {
+        return engine == null ? null : GuiHost.get().overlayFor(engine, openerId);
+    }
+
+    static void registerHotloadHook(Runnable onHotload) {
+        GuiHost.get().registerHotloadHook(onHotload);
+    }
+
+    static void unregisterHotloadHook(Runnable onHotload) {
+        GuiHost.get().unregisterHotloadHook(onHotload);
+    }
+
+    static void interruptOnPluginShutdown(ExecutorService executor) {
+        PreservationRegistry preservation = IrisServices.getOrNull(PreservationRegistry.class);
+        if (preservation != null) {
+            preservation.register(executor);
+        }
+    }
+
+    static void interruptOnPluginShutdown(Thread thread) {
+        PreservationRegistry preservation = IrisServices.getOrNull(PreservationRegistry.class);
+        if (preservation != null) {
+            preservation.register(thread);
+        }
+    }
+
+    private static Engine usable(Engine engine) {
+        return engine == null || engine.isClosed() || engine.isClosing() ? null : engine;
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/MapHoverCard.java

@@ -0,0 +1,538 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.MapHoverProbe.PickStep;
+import art.arcane.iris.studio.map.MapHoverProbe.StepKind;
+import art.arcane.iris.studio.map.NoisePickSpread.Band;
+import art.arcane.iris.studio.map.components.MapLabels;
+import art.arcane.iris.studio.map.components.TileType;
+import art.arcane.iris.pack.loading.IrisRegistrant;
+import art.arcane.iris.generation.biome.IrisBiome;
+
+import java.awt.Color;
+import java.awt.Font;
+import java.awt.FontMetrics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+import java.util.Optional;
+
+/**
+ * The card that follows the cursor: the biome and its region, the ground's height, and a row per noise that picked
+ * them, each split into one segment per option with the picked one lit and a line at the spot's value. Shift adds the
+ * terrain, location and pack files; a footer bar lists the shortcuts.
+ */
+record MapHoverCard(Header header, String subtitle, List<NoiseRow> noiseRows, List<Group> groups, List<Hint> hints) {
+    private static final int MINIMUM_CONTENT_WIDTH = 240;
+    private static final int MINIMUM_SEGMENTS_WIDTH = 120;
+    private static final int PADDING_X = 12;
+    private static final int PADDING_TOP = 9;
+    private static final int PADDING_BOTTOM = 11;
+    private static final int ICON_SIZE = 12;
+    private static final int ICON_GAP = 8;
+    private static final int REGION_GAP = 16;
+    private static final int ROWS_GAP = 9;
+    private static final int ROW_HEIGHT = 18;
+    private static final int COLUMN_GAP = 8;
+    private static final int SEGMENT_HEIGHT = 6;
+    private static final int WIDE_SEGMENT_GAP = 2;
+    private static final int NARROW_SEGMENT_GAP = 1;
+    private static final int WIDE_SEGMENT_WIDTH = 8;
+    private static final int NARROW_SEGMENT_WIDTH = 3;
+    private static final int MARKER_WIDTH = 2;
+    private static final int MARKER_HEIGHT = 12;
+    private static final int GROUP_GAP = 8;
+    private static final int GROUP_TITLE_GAP = 4;
+    private static final int DETAIL_COLUMN_GAP = 14;
+    private static final int DETAIL_ROW_GAP = 3;
+    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));
+
+    /**
+     * @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 adds the terrain, location and pack files
+     */
+    static MapHoverCard of(MapLabels.Label subject, MapLabels.Label region, MapHoverProbe.Details details,
+                           TileType 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, region, biome, path), subtitle(details, path), noiseRows(path), groups,
+                hints(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 paddingX = StudioTheme.scale(PADDING_X);
+        int contentWidth = contentWidth(card);
+        int width = contentWidth + paddingX * 2;
+        int footerHeight = footerHeight(card);
+        int height = StudioTheme.scale(PADDING_TOP) + headerHeight(card) + rowsHeight() + groupsHeight(card)
+                + StudioTheme.scale(PADDING_BOTTOM) + footerHeight;
+        int x = Math.max(paddingX, Math.min(boundsWidth - width - paddingX, anchorX));
+        int y = Math.max(paddingX, Math.min(boundsHeight - height - paddingX, anchorY));
+        StudioOverlay.drawCard(card, x, y, width, height, footerHeight);
+
+        int left = x + paddingX;
+        int top = y + StudioTheme.scale(PADDING_TOP);
+        top = drawHeader(card, left, top, contentWidth);
+        top = drawNoiseRows(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), rowsWidth(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 and name with its region on the right, and the ground below.
+    private int headerTextOffset() {
+        return header.color() == null ? 0 : StudioTheme.scale(ICON_SIZE + ICON_GAP);
+    }
+
+    private int headerWidth(Graphics2D canvas) {
+        FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+        int width = headerTextOffset() + canvas.getFontMetrics(StudioTheme.boldFont()).stringWidth(header.name());
+        if (header.region() != null) {
+            width += StudioTheme.scale(REGION_GAP) + small.stringWidth(header.region());
+        }
+        if (subtitle != null) {
+            width = Math.max(width, headerTextOffset() + small.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());
+        FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+        if (header.color() != null) {
+            int iconSize = StudioTheme.scale(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.region() != null) {
+            drawText(canvas, header.region(), StudioTheme.smallFont(), StudioTheme.MUTED_TEXT,
+                    left + contentWidth - small.stringWidth(header.region()), baseline);
+        }
+        top += bold.getHeight();
+        if (subtitle != null) {
+            drawText(canvas, subtitle, StudioTheme.smallFont(), StudioTheme.SECONDARY_TEXT, textLeft, top + small.getAscent());
+            top += small.getHeight();
+        }
+        return top;
+    }
+
+    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);
+    }
+
+    // Noise rows: a muted label, the segments (or in hybrid terrain how the biome won), and the value on the right.
+    private int labelColumnWidth(Graphics2D canvas) {
+        FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+        return noiseRows.stream().mapToInt(row -> small.stringWidth(row.label())).max().orElse(0);
+    }
+
+    private int valueColumnWidth(Graphics2D canvas) {
+        FontMetrics value = canvas.getFontMetrics(valueFont());
+        return noiseRows.stream().mapToInt(row -> value.stringWidth(row.value())).max().orElse(0);
+    }
+
+    private int rowsWidth(Graphics2D canvas) {
+        if (noiseRows.isEmpty()) {
+            return 0;
+        }
+        FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+        int middle = noiseRows.stream()
+                .mapToInt(row -> row.showsSegments() ? StudioTheme.scale(MINIMUM_SEGMENTS_WIDTH) : small.stringWidth(row.note()))
+                .max().orElse(0);
+        return labelColumnWidth(canvas) + valueColumnWidth(canvas) + middle + StudioTheme.scale(COLUMN_GAP) * 2;
+    }
+
+    private int rowsHeight() {
+        return noiseRows.isEmpty() ? 0 : StudioTheme.scale(ROWS_GAP) + noiseRows.size() * StudioTheme.scale(ROW_HEIGHT);
+    }
+
+    private int drawNoiseRows(Graphics2D canvas, int left, int top, int contentWidth) {
+        if (noiseRows.isEmpty()) {
+            return top;
+        }
+        top += StudioTheme.scale(ROWS_GAP);
+        int rowHeight = StudioTheme.scale(ROW_HEIGHT);
+        int columnGap = StudioTheme.scale(COLUMN_GAP);
+        int middleLeft = left + labelColumnWidth(canvas) + columnGap;
+        int valueRight = left + contentWidth;
+        int middleWidth = valueRight - valueColumnWidth(canvas) - columnGap - middleLeft;
+        FontMetrics small = canvas.getFontMetrics(StudioTheme.smallFont());
+        FontMetrics value = canvas.getFontMetrics(valueFont());
+        for (NoiseRow row : noiseRows) {
+            int baseline = top + (rowHeight - small.getHeight()) / 2 + small.getAscent();
+            drawText(canvas, row.label(), StudioTheme.smallFont(), StudioTheme.MUTED_TEXT, left, baseline);
+            if (row.showsSegments()) {
+                drawSegments(canvas, row, middleLeft, top + (rowHeight - StudioTheme.scale(SEGMENT_HEIGHT)) / 2, middleWidth);
+            } else {
+                drawText(canvas, row.note(), StudioTheme.smallFont(), StudioTheme.SECONDARY_TEXT, middleLeft, baseline);
+            }
+            drawText(canvas, row.value(), valueFont(), StudioTheme.SECONDARY_TEXT, valueRight - value.stringWidth(row.value()),
+                    baseline);
+            top += rowHeight;
+        }
+        return top;
+    }
+
+    // One segment per band, as wide as the band's share of the noise; the picked one in its option's colour.
+    private static void drawSegments(Graphics2D canvas, NoiseRow row, int left, int top, int width) {
+        List<Band> bands = row.bands();
+        int height = StudioTheme.scale(SEGMENT_HEIGHT);
+        int gap = segmentGap(width, bands.size());
+        int picked = pickedBandIndex(bands, row.noise());
+        int arc = StudioTheme.scale(2);
+        for (int index = 0; index < bands.size(); index++) {
+            Band band = bands.get(index);
+            int from = left + (int) Math.round(band.fromNoise() * width);
+            int to = left + (int) Math.round(band.toNoise() * width);
+            int segmentWidth = Math.max(1, to - from - (index == bands.size() - 1 ? 0 : gap));
+            canvas.setColor(index == picked ? new Color(band.option().color()) : StudioTheme.OVERLAY_BORDER);
+            canvas.fillRoundRect(from, top, segmentWidth, height, arc, arc);
+        }
+        drawMarker(canvas, left + (int) Math.round(Math.clamp(row.noise(), 0D, 1D) * width), top + height / 2);
+    }
+
+    private static int segmentGap(int width, int segmentCount) {
+        int averageWidth = width / Math.max(1, segmentCount);
+        if (averageWidth >= StudioTheme.scale(WIDE_SEGMENT_WIDTH)) {
+            return StudioTheme.scale(WIDE_SEGMENT_GAP);
+        }
+        return averageWidth >= StudioTheme.scale(NARROW_SEGMENT_WIDTH) ? StudioTheme.scale(NARROW_SEGMENT_GAP) : 0;
+    }
+
+    // The engine gives values below 0 the first option and values above 1 the last, the same as this.
+    private static int pickedBandIndex(List<Band> bands, double noise) {
+        for (int index = 0; index < bands.size(); index++) {
+            if (noise <= bands.get(index).toNoise()) {
+                return index;
+            }
+        }
+        return bands.size() - 1;
+    }
+
+    private static void drawMarker(Graphics2D canvas, int centerX, int centerY) {
+        int width = StudioTheme.scale(MARKER_WIDTH);
+        int height = StudioTheme.scale(MARKER_HEIGHT);
+        int left = centerX - width / 2;
+        int top = centerY - height / 2;
+        canvas.setColor(StudioTheme.PANEL_BACKGROUND);
+        canvas.fillRect(left - 1, top - 1, width + 2, height + 2);
+        canvas.setColor(StudioTheme.TEXT);
+        canvas.fillRect(left, top, width, height);
+    }
+
+    private static Font valueFont() {
+        return StudioTheme.monospacedFont().deriveFont(StudioTheme.smallFont().getSize2D());
+    }
+
+    // Groups: sentence-case titles over rows of muted labels and values, all labels in one column.
+    private int detailLabelWidth(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) {
+        if (groups.isEmpty()) {
+            return 0;
+        }
+        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 detailLabelWidth(canvas) + StudioTheme.scale(DETAIL_COLUMN_GAP) + valueWidth;
+    }
+
+    private int groupsHeight(Graphics2D canvas) {
+        int rowHeight = canvas.getFontMetrics(StudioTheme.font()).getHeight() + StudioTheme.scale(DETAIL_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 + detailLabelWidth(canvas) + StudioTheme.scale(DETAIL_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(DETAIL_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, TileType type) {
+        if (subject != null && subject.subject() instanceof IrisBiome biome) {
+            return biome;
+        }
+        if (details == null) {
+            return null;
+        }
+        return type == TileType.CAVE_LAND ? details.caveBiome() : details.surfaceBiome();
+    }
+
+    private static Header header(MapLabels.Label subject, MapLabels.Label region, IrisBiome biome, List<PickStep> path) {
+        String regionName = path.stream()
+                .filter(step -> step.kind() == StepKind.REGION_NOISE || step.kind() == StepKind.PREVIEWED_REGION)
+                .map(step -> step.picked().name())
+                .findFirst()
+                .orElse(region == null ? null : region.name());
+        if (biome != null) {
+            return new Header(biome.getName(), colorOf(biome, path), regionName);
+        }
+        if (subject != null) {
+            return new Header(subject.name(), null, subject.kind() == MapLabels.Kind.REGION ? null : regionName);
+        }
+        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, List<PickStep> path) {
+        if (details == null) {
+            return null;
+        }
+        String ground = Math.round(details.height()) + " · " + signedHeight(details.height() - details.fluidHeight())
+                + " · " + Math.round(details.slopeDegrees()) + "°";
+        return parentOfChild(path).map(parent -> "child of " + parent + " · " + ground).orElse(ground);
+    }
+
+    // A child biome took the spot from the biome the noise picked, which is the step before it.
+    private static Optional<String> parentOfChild(List<PickStep> path) {
+        for (int index = 1; index < path.size(); index++) {
+            if (path.get(index).kind() == StepKind.CHILD) {
+                return Optional.of(path.get(index - 1).picked().name());
+            }
+        }
+        return Optional.empty();
+    }
+
+    private static List<NoiseRow> noiseRows(List<PickStep> path) {
+        List<NoiseRow> rows = new ArrayList<>();
+        for (PickStep step : path) {
+            switch (step.kind()) {
+                case REGION_NOISE -> rows.add(new NoiseRow("Region", step.bands(), step.noise(), null, step.value()));
+                case BIOME_NOISE -> rows.add(new NoiseRow(capitalize(step.detail()), step.bands(), step.noise(), null,
+                        step.value()));
+                case PREVIEWED_REGION, CHILD -> {
+                }
+            }
+        }
+        return rows;
+    }
+
+    private static void addTerrainGroup(List<Group> groups, MapHoverProbe.Details details, TileType type) {
+        if (details == null) {
+            return;
+        }
+        List<Row> rows = new ArrayList<>();
+        IrisBiome surface = details.surfaceBiome();
+        IrisBiome cave = details.caveBiome();
+        if (type == TileType.CAVE_LAND && surface != null) {
+            rows.add(new Row("Surface biome", surface.getName(), false));
+        } else if (type != TileType.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(boolean detailed) {
+        List<Hint> hints = new ArrayList<>();
+        if (!detailed) {
+            hints.add(new Hint("Shift", "More"));
+        }
+        hints.add(new Hint("H", "Highlight"));
+        hints.add(new Hint("Alt+Click", "Open file"));
+        return hints;
+    }
+
+    private static String signedHeight(double height) {
+        long rounded = Math.round(height);
+        return rounded < 0 ? "−" + -rounded : "+" + rounded;
+    }
+
+    private static String capitalize(String text) {
+        return text.substring(0, 1).toUpperCase(Locale.ROOT) + text.substring(1);
+    }
+
+    /**
+     * @param color  the biome's map colour, or null when no step of the path tells it
+     * @param region the region's name, or null when the title already is the region
+     */
+    record Header(String name, Integer color, String region) {
+    }
+
+    /**
+     * @param bands the bands the noise splits into, empty when no noise picked the step
+     * @param note  how the step was picked when no noise did, or null
+     */
+    record NoiseRow(String label, List<Band> bands, double noise, String note, String value) {
+        boolean showsSegments() {
+            return !bands.isEmpty();
+        }
+    }
+
+    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/art/arcane/iris/studio/map/MapHoverProbe.java

@@ -0,0 +1,158 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.NoisePickSpread.Band;
+import art.arcane.iris.studio.map.NoisePickSpread.Option;
+import art.arcane.iris.generation.runtime.IrisComplex;
+import art.arcane.iris.generation.runtime.Engine;
+import art.arcane.iris.generation.terrain.InferredType;
+import art.arcane.iris.generation.biome.IrisBiome;
+import art.arcane.iris.generation.terrain.IrisDimension;
+import art.arcane.iris.generation.terrain.IrisRegion;
+
+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 = previewRegion != null
+                ? complex.surfacePickAsIfIn(region, worldX, worldZ)
+                : complex.basePickIn(region, worldX, worldZ);
+        String vanillaBiomeKey = complex.getTrueBiomeStream().get(worldX, worldZ).getDerivativeKey();
+        double slope = complex.getSlopeStream().getDouble(worldX, worldZ);
+        IrisDimension dimension = engine.getDimension();
+        return new Details(
+                worldX,
+                worldZ,
+                surfacePick.biome(),
+                complex.getCaveBiomeStream().get(worldX, worldZ),
+                region,
+                vanillaBiomeKey == null ? null : vanillaBiomeKey.substring(vanillaBiomeKey.indexOf(':') + 1),
+                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. Each explains the biome it
+    // draws: the preview its surface biome, the real map its base biome, before the height corrects it near coasts.
+    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 = noiseStep(engine, region, surfacePick.type(), x, z);
+        path.add(biomeStep);
+        if (!biomeStep.picked().key().equals(surfacePick.biome().getLoadKey())) {
+            path.add(new PickStep(StepKind.CHILD, PickMeasuring.biomeOption(engine, surfacePick.biome()), null, 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(StepKind.REGION_NOISE, PickMeasuring.regionOption(engine, region), null, noiseText(noise),
+                NoisePickSpread.splitNoise(regions), noise);
+    }
+
+    private static PickStep previewedRegionStep(Engine engine, IrisRegion region) {
+        return new PickStep(StepKind.PREVIEWED_REGION, PickMeasuring.regionOption(engine, region), null, 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(StepKind.BIOME_NOISE, PickMeasuring.biomeOption(engine, picked), typeName(type), noiseText(noise),
+                NoisePickSpread.splitNoise(biomes), noise);
+    }
+
+    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);
+    }
+
+    record Details(
+            double worldX,
+            double worldZ,
+            IrisBiome surfaceBiome,
+            IrisBiome caveBiome,
+            IrisRegion region,
+            String vanillaBiome,
+            double height,
+            double fluidHeight,
+            double slopeDegrees,
+            List<PickStep> pickPath
+    ) {
+    }
+
+    /**
+     * How a step on the way to the spot's biome was picked.
+     */
+    enum StepKind {
+        REGION_NOISE,
+        PREVIEWED_REGION,
+        BIOME_NOISE,
+        CHILD
+    }
+
+    /**
+     * One step on the way to the spot's biome, starting with its region.
+     *
+     * @param detail the biome list the step picked from; null for the rest
+     * @param value  the noise value 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(StepKind kind, Option picked, String detail, String value, List<Band> bands, double noise) {
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/MapLegendPanel.java

@@ -0,0 +1,244 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.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) {
+        this();
+        highlightOnClick(onRowClicked);
+    }
+
+    /**
+     * A legend whose rows only tell what is on screen; clicking them does nothing.
+     */
+    static MapLegendPanel listingOnly() {
+        return new MapLegendPanel();
+    }
+
+    private MapLegendPanel() {
+        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));
+        add(StudioToolbar.scroll(list), BorderLayout.CENTER);
+    }
+
+    private void highlightOnClick(Consumer<MapCensus.Share> onRowClicked) {
+        list.addMouseListener(new MouseAdapter() {
+            @Override
+            public void mouseClicked(MouseEvent event) {
+                MapCensus.Share share = shareAt(event.getPoint());
+                if (share != null) {
+                    onRowClicked.accept(share);
+                }
+            }
+        });
+        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/art/arcane/iris/studio/map/MapView.java

@@ -0,0 +1,123 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.components.TileType;
+
+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, TileType.BIOME, KeyEvent.VK_1),
+    REGIONS("Regions", "The region each spot belongs to; pick one to see the biomes it places",
+            Group.WORLD, TileType.REGION, KeyEvent.VK_2),
+    HEIGHT("Height", "Terrain height, from deep water to snowy peaks", Group.WORLD, TileType.HEIGHT, KeyEvent.VK_3),
+    RIVERS("Rivers", "Rivers, falls, grottos and the rest of the hydrology the engine plans",
+            Group.WORLD, TileType.RIVER, KeyEvent.VK_4),
+    WORLD_3D("3D world", "The terrain in 3D, coloured by biome or region", Group.WORLD, null, KeyEvent.VK_5),
+    LAND_BIOMES("Land biomes", "The land biome each spot would get, also where the sea is",
+            Group.BIOME_STREAMS, TileType.BIOME_LAND, KeyEvent.VK_6),
+    SEA_BIOMES("Sea biomes", "The sea biome each spot would get, also where the land is",
+            Group.BIOME_STREAMS, TileType.BIOME_SEA, KeyEvent.VK_7),
+    CAVE_BIOMES("Cave biomes", "The cave biome under each spot", Group.BIOME_STREAMS, TileType.CAVE_LAND, KeyEvent.VK_8),
+    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),
+    IMAGE_MAPS("Image maps", "Terrain height, biomes or masks painted from a PNG, previewed and exported into the pack",
+            Group.GENERATORS, null, KeyEvent.VK_I);
+
+    private final String label;
+    private final String description;
+    private final Group group;
+    private final TileType renderType;
+    private final int shortcutKey;
+
+    MapView(String label, String description, Group group, TileType 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 3D world, palette, object, procedural, noise and image map
+     * views, which draw themselves.
+     */
+    TileType 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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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 in iris/icons).
+ */
+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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/MapWindow.java

@@ -0,0 +1,650 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.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, noise and image map
+ * explorers as its Palettes, Objects, Noise and Image maps 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 String WORLD_CARD = "world";
+    private static final String IMAGE_MAPS_CARD = "image maps";
+    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 double WORLD_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 List<JComponent> worldControls = new ArrayList<>();
+    private final List<JComponent> imageMapControls = 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 ResourceUsage resourceUsage = new ResourceUsage();
+    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 WorldExplorer worldExplorer;
+    private ImageMapExplorer imageMapExplorer;
+    private double worldCenterX;
+    private double worldCenterZ;
+    private MapView currentView;
+    private double paletteCenterX;
+    private double paletteCenterZ;
+
+    private MapWindow(PaletteExplorerStart start) {
+        this.start = start;
+        this.frame = MapHost.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) {
+        openLater(start, MapView.BIOMES);
+    }
+
+    public static void openPalettes(PaletteExplorerStart start) {
+        openLater(start, MapView.PALETTES);
+    }
+
+    public static void openNoise(PaletteExplorerStart start) {
+        openLater(start, MapView.NOISE);
+    }
+
+    public static void openImageMaps(PaletteExplorerStart start) {
+        openLater(start, MapView.IMAGE_MAPS);
+    }
+
+    private static void openLater(PaletteExplorerStart start, MapView initialView) {
+        if (!MapHost.isAvailable()) {
+            return;
+        }
+        EventQueue.invokeLater(() -> open(start, initialView));
+    }
+
+    private static void open(PaletteExplorerStart start, MapView initialView) {
+        if (!MapHost.isAvailable()) {
+            return;
+        }
+        StudioTheme.install();
+        MapWindow window = new MapWindow(start);
+        window.frame.setVisible(true);
+        window.canvas.start();
+        window.resourceUsage.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(MapHost.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(resourceUsage);
+        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 (previousView == MapView.WORLD_3D) {
+            worldExplorer.hide();
+        }
+        if (view.isTileMap()) {
+            showMap(previousView, view);
+        } else if (view == MapView.WORLD_3D) {
+            showWorld();
+        } else if (view == MapView.PALETTES) {
+            showPalettes(previousView);
+        } else if (view == MapView.OBJECTS || view == MapView.PROCEDURAL) {
+            showObjectExplorer(view);
+        } else if (view == MapView.IMAGE_MAPS) {
+            showImageMaps();
+        } 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();
+        }
+    }
+
+    // The 3D world keeps its camera unless the map was moved since; then it turns around the map's middle.
+    private void showWorld() {
+        boolean firstOpen = worldExplorer == null;
+        if (firstOpen) {
+            createWorldExplorer();
+        }
+        boolean mapMoved = Math.hypot(canvas.centerX() - worldCenterX, canvas.centerZ() - worldCenterZ) >= WORLD_RECENTER_DISTANCE_BLOCKS;
+        worldCenterX = canvas.centerX();
+        worldCenterZ = canvas.centerZ();
+        canvas.setActive(false);
+        showControls(worldControls, explorerControls);
+        useSidebar(viewListScroll);
+        inspectorSlot.removeAll();
+        inspectorSlot.add(worldExplorer.legend(), BorderLayout.CENTER);
+        showCard(WORLD_CARD);
+        worldExplorer.show(worldCenterX, worldCenterZ, firstOpen || mapMoved);
+    }
+
+    private void createWorldExplorer() {
+        worldExplorer = new WorldExplorer(canvas::engine);
+        keepClearOfIsland(worldExplorer::setCoveredLeftWidth);
+        worldControls.addAll(worldExplorer.controls());
+        worldControls.forEach(control -> toolbar.add(control, toolbar.getComponentIndex(resetViewButton)));
+        content.add(worldExplorer.view(), WORLD_CARD);
+        statusBars.add(worldExplorer.statusBar(), WORLD_CARD);
+    }
+
+    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();
+        }
+    }
+
+    private void showImageMaps() {
+        boolean firstOpen = imageMapExplorer == null;
+        if (firstOpen) {
+            createImageMapExplorer();
+        }
+        canvas.setActive(false);
+        showControls(imageMapControls);
+        useSidebar(viewListScroll);
+        inspectorSlot.removeAll();
+        showCard(IMAGE_MAPS_CARD);
+        if (firstOpen) {
+            imageMapExplorer.open();
+        }
+    }
+
+    private void createImageMapExplorer() {
+        imageMapExplorer = new ImageMapExplorer(start.engine());
+        keepClearOfIsland(imageMapExplorer::setCoveredLeftWidth);
+        imageMapControls.addAll(imageMapExplorer.controls());
+        imageMapControls.forEach(control -> toolbar.add(control, toolbar.getComponentIndex(resetViewButton)));
+        content.add(imageMapExplorer.view(), IMAGE_MAPS_CARD);
+        statusBars.add(imageMapExplorer.statusBar(), IMAGE_MAPS_CARD);
+    }
+
+    // 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());
+        keepClearOfIsland(noiseExplorer::setCoveredLeftWidth);
+        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();
+        if (worldExplorer != null) {
+            worldExplorer.refresh(worldCenterX, worldCenterZ);
+        }
+    }
+
+    // Only called for the view on screen, whose explorer exists by then.
+    private void resetExplorerView() {
+        switch (currentView) {
+            case WORLD_3D -> worldExplorer.resetCamera();
+            case OBJECTS, PROCEDURAL -> objectExplorers.get(currentView).resetCamera();
+            case NOISE -> noiseExplorer.resetViewport();
+            case PALETTES -> paletteExplorer.resetViewport();
+            default -> {
+            }
+        }
+    }
+
+    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, worldControls, imageMapControls)) {
+            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() {
+        resourceUsage.stop();
+        canvas.close();
+        regionExplorer.close();
+        biomeExplorer.close();
+        if (paletteExplorer != null) {
+            paletteExplorer.close();
+        }
+        objectExplorers.values().forEach(ObjectExplorer::close);
+        if (noiseExplorer != null) {
+            noiseExplorer.close();
+        }
+        if (worldExplorer != null) {
+            worldExplorer.close();
+        }
+        if (imageMapExplorer != null) {
+            imageMapExplorer.close();
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/MinecraftBiomeColors.java

@@ -0,0 +1,162 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import art.arcane.iris.generation.biome.IrisBiomeCustom;
+
+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 static final String DEFAULT_NAMESPACE = "minecraft";
+
+    private final Map<String, 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)
+        );
+    }
+
+    /**
+     * @param biome a biome key like {@code minecraft:plains}; one without a namespace is taken as Minecraft's
+     */
+    BiomeTintColors vanilla(String 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(String 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(String biome) {
+        int separator = biome.indexOf(':');
+        String namespace = separator < 0 ? DEFAULT_NAMESPACE : biome.substring(0, separator);
+        String path = biome.substring(separator + 1);
+        try {
+            return ClientJarFiles.readJson(clientJar, "data/" + namespace + "/worldgen/biome/" + path + ".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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import art.arcane.iris.spi.IrisLogging;
+import art.arcane.iris.spi.IrisPlatforms;
+
+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(IrisPlatforms.get().minecraftVersion(), 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 IrisPlatforms.get().dataFile("cache", "minecraft-client", IrisPlatforms.get().minecraftVersion() + ".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/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/NoiseColumns.java

@@ -0,0 +1,42 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.volmlib.util.function.NoiseProvider;
+
+import java.util.function.DoubleUnaryOperator;
+
+/**
+ * Noise as terrain columns: each value raised to a height and coloured by the noise's colour scale.
+ *
+ * @param heightOf turns a noise value into a height in blocks
+ */
+record NoiseColumns(NoiseProvider noise, DoubleUnaryOperator heightOf, NoiseColorScale colorScale) implements TerrainColumns {
+    @Override
+    public void sampleRow(TerrainGrid grid, int row, float[] heights, int[] colors) {
+        double worldZ = grid.originZ() + (double) row * grid.step();
+        for (int column = 0; column < grid.columns(); column++) {
+            double worldX = grid.originX() + (double) column * grid.step();
+            double value = noise.noise(worldX, worldZ);
+            int index = row * grid.columns() + column;
+            heights[index] = Double.isFinite(value) ? (float) heightOf.applyAsDouble(value) : Float.NaN;
+            colors[index] = Double.isFinite(value) ? colorScale.colorAt(value, worldX, worldZ) : 0;
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/NoisePalette.java

@@ -1,8 +1,26 @@
-package art.arcane.iris.studio.view;
+/*
+ * 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 art.arcane.iris.studio.map;
 
 import java.awt.Color;
 
-enum NoisePalette {
+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});
@@ -30,7 +48,8 @@ enum NoisePalette {
         return colorFinite(value);
     }
 
-    int colorFinite(double value) {
+    @Override
+    public int colorFinite(double value) {
         double normalized = (value - minimum) / (maximum - minimum);
         return colorNormalized(normalized);
     }
@@ -40,20 +59,29 @@ enum NoisePalette {
         return lookup[(int) Math.round(clipped * (lookup.length - 1))];
     }
 
-    Color displayColorNormalized(double normalized) {
+    @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))];
     }
 
-    String label() {
+    @Override
+    public String label() {
         return label;
     }
 
-    double minimum() {
+    @Override
+    public double minimum() {
         return minimum;
     }
 
-    double maximum() {
+    @Override
+    public double maximum() {
         return maximum;
     }
 

core/src/main/java/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/NoisePickSpread.java

@@ -0,0 +1,158 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+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 NoisePickSpread(String title, List<Band> bands) {
+        this.title = title;
+        this.bands = List.copyOf(bands);
+        this.samplesByBand = new long[bands.size()];
+    }
+
+    static NoisePickSpread of(String title, List<Option> options) {
+        return new NoisePickSpread(title, splitNoise(options));
+    }
+
+    /**
+     * The band of noise each option gets, in the order the noise meets them.
+     */
+    static List<Band> splitNoise(List<Option> options) {
+        return bands(options);
+    }
+
+    void add(double noise) {
+        if (bands.isEmpty() || !Double.isFinite(noise)) {
+            return;
+        }
+        sampleCount++;
+        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;
+    }
+
+    /**
+     * 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 RarityStream: 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;
+    }
+
+    /**
+     * 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/art/arcane/iris/studio/map/NoiseRenderCoordinator.java

@@ -1,14 +1,28 @@
-package art.arcane.iris.studio.view;
+/*
+ * 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 art.arcane.iris.studio.map;
 
-import art.arcane.iris.generation.runtime.PreservationRegistry;
-import art.arcane.iris.spi.IrisServices;
 import art.arcane.volmlib.util.function.NoiseProvider;
 
 import java.awt.image.BufferedImage;
-import java.awt.image.DataBufferInt;
 import java.util.Objects;
-import java.util.concurrent.ArrayBlockingQueue;
-import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.ThreadPoolExecutor;
@@ -19,10 +33,11 @@ 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 ThreadFactory workerThreadFactory;
-    private final ThreadFactory coordinatorThreadFactory;
+    private final ThreadPoolExecutor workers;
     private final AtomicReference<RenderGeneration> latestRequested = new AtomicReference<>();
     private final AtomicLong latestRevision = new AtomicLong();
     private final AtomicBoolean closed = new AtomicBoolean();
@@ -35,18 +50,16 @@ final class NoiseRenderCoordinator implements AutoCloseable {
         this.workerCount = Math.max(1, workerCount);
         this.listener = Objects.requireNonNull(listener, "listener");
         AtomicInteger threadIds = new AtomicInteger();
-        workerThreadFactory = runnable -> {
+        ThreadFactory workerThreadFactory = runnable -> {
             Thread thread = new Thread(runnable, "Iris Noise Renderer " + threadIds.incrementAndGet());
             thread.setDaemon(true);
             thread.setPriority(Thread.MIN_PRIORITY);
             return thread;
         };
-        coordinatorThreadFactory = runnable -> {
-            Thread thread = new Thread(runnable, "Iris Noise Coordinator " + 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);
+        MapHost.interruptOnPluginShutdown(workers);
     }
 
     void request(Request request) {
@@ -55,15 +68,23 @@ final class NoiseRenderCoordinator implements AutoCloseable {
             return;
         }
         latestRevision.accumulateAndGet(request.revision(), Math::max);
-        cancelActiveRender();
-        RenderGeneration generation = createGeneration(request);
+        RenderGeneration generation = new RenderGeneration(request, Math.min(workerCount * BANDS_PER_WORKER, outputHeight(request)));
         latestRequested.set(generation);
-        generation.start();
+        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);
-        cancelActiveRender();
+        latestRequested.set(null);
     }
 
     boolean isClosed() {
@@ -120,95 +141,49 @@ final class NoiseRenderCoordinator implements AutoCloseable {
             return;
         }
         latestRevision.incrementAndGet();
-        cancelActiveRender();
+        latestRequested.set(null);
+        workers.shutdownNow();
     }
 
-    private void renderGeneration(RenderGeneration generation) {
-        Request request = generation.request();
-        if (!isCurrent(request)) {
-            generation.close();
-            return;
-        }
-        listener.onRenderStarted(request);
+    // 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 {
-            Result result = render(generation);
-            if (result != null && isCurrent(request)) {
-                listener.onRenderCompleted(result);
+            if (isCurrent(generation)) {
+                renderRows(generation, bandIndex);
             }
         } catch (Throwable error) {
-            if (isCurrent(request)) {
-                listener.onRenderFailed(request, error);
-            }
+            generation.fail(error);
         } finally {
-            latestRequested.compareAndSet(generation, null);
-            generation.close();
+            finishBand(generation);
         }
     }
 
-    private Result render(RenderGeneration generation) throws InterruptedException {
+    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();
-        long started = System.nanoTime();
-        int outputWidth = Math.max(1, (request.width() + request.sampleStep() - 1) / request.sampleStep());
-        int outputHeight = Math.max(1, (request.height() + request.sampleStep() - 1) / request.sampleStep());
-        BufferedImage image = new BufferedImage(outputWidth, outputHeight, BufferedImage.TYPE_INT_RGB);
-        int[] pixels = ((DataBufferInt) image.getRaster().getDataBuffer()).getData();
-        int bandCount = Math.min(workerCount, outputHeight);
-        BandStats[] bandStats = new BandStats[bandCount];
-        CountDownLatch completion = new CountDownLatch(bandCount);
-        AtomicReference<Throwable> failure = new AtomicReference<>();
-        for (int band = 0; band < bandCount; band++) {
-            bandStats[band] = new BandStats();
-        }
-        for (int band = 0; band < bandCount; band++) {
-            int bandIndex = band;
-            Runnable task = () -> {
-                try {
-                    renderBand(request, image, pixels, bandIndex, bandCount, bandStats[bandIndex]);
-                } catch (Throwable error) {
-                    failure.compareAndSet(null, error);
-                } finally {
-                    completion.countDown();
-                }
-            };
-            try {
-                generation.executor().execute(task);
-            } catch (RejectedExecutionException exception) {
-                failure.compareAndSet(null, exception);
-                completion.countDown();
-            }
-        }
-        completion.await();
-        Throwable renderFailure = failure.get();
-        if (renderFailure != null) {
-            if (renderFailure instanceof RuntimeException runtimeException) {
-                throw runtimeException;
-            }
-            if (renderFailure instanceof Error error) {
-                throw error;
-            }
-            throw new IllegalStateException("Noise rendering failed", renderFailure);
-        }
-        if (!isCurrent(request)) {
-            return null;
-        }
-        RenderStats combined = combine(bandStats);
-        double milliseconds = (System.nanoTime() - started) / 1_000_000D;
-        return new Result(request, image, milliseconds, combined.samples, combined.minimum, combined.maximum,
-                combined.centerValue, combined.underflow, combined.overflow, combined.invalid);
-    }
-
-    private void renderBand(Request request, BufferedImage image, int[] pixels, int bandIndex, int bandCount,
-                            BandStats stats) {
-        int outputWidth = image.getWidth();
-        int outputHeight = image.getHeight();
-        int fromY = (outputHeight * bandIndex) / bandCount;
-        int toY = (outputHeight * (bandIndex + 1)) / bandCount;
+        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();
-        NoisePalette palette = request.palette();
-        double paletteMinimum = palette.minimum();
-        double paletteMaximum = palette.maximum();
+        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());
@@ -216,16 +191,16 @@ final class NoiseRenderCoordinator implements AutoCloseable {
             int pixelIndex = y * outputWidth;
             boolean centerRow = y == outputHeight / 2;
             for (int x = 0; x < outputWidth; x++) {
-                if ((x & 31) == 0 && (!isCurrent(request) || Thread.currentThread().isInterrupted())) {
+                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++] = palette.colorFinite(value);
+                    pixels[pixelIndex++] = colorScale.colorAt(value, worldX, worldZ);
                     stats.acceptFinite(value, center, paletteMinimum, paletteMaximum);
                 } else {
-                    pixels[pixelIndex++] = NoisePalette.INVALID_COLOR;
+                    pixels[pixelIndex++] = colorScale.colorInvalidAt(worldX, worldZ);
                     stats.acceptInvalid(value, center);
                 }
                 worldX += worldStep;
@@ -233,41 +208,18 @@ final class NoiseRenderCoordinator implements AutoCloseable {
         }
     }
 
-    private boolean isCurrent(Request request) {
+    private boolean isCurrent(RenderGeneration generation) {
         return !closed.get()
-                && latestRequested.get() != null
-                && latestRequested.get().request() == request
-                && request.revision() >= latestRevision.get();
+                && latestRequested.get() == generation
+                && generation.request().revision() >= latestRevision.get();
     }
 
-    private void cancelActiveRender() {
-        RenderGeneration generation = latestRequested.getAndSet(null);
-        if (generation != null) {
-            generation.close();
-        }
+    private static int outputWidth(Request request) {
+        return Math.max(1, (request.width() + request.sampleStep() - 1) / request.sampleStep());
     }
 
-    private RenderGeneration createGeneration(Request request) {
-        ThreadPoolExecutor executor = new ThreadPoolExecutor(
-                workerCount,
-                workerCount,
-                0L,
-                TimeUnit.MILLISECONDS,
-                new ArrayBlockingQueue<>(Math.max(1, workerCount)),
-                workerThreadFactory,
-                new ThreadPoolExecutor.AbortPolicy()
-        );
-        PreservationRegistry preservation = IrisServices.getOrNull(PreservationRegistry.class);
-        if (preservation != null) {
-            preservation.register(executor);
-        }
-        RenderGeneration generation = new RenderGeneration(request, executor);
-        Thread actualRunner = coordinatorThreadFactory.newThread(() -> renderGeneration(generation));
-        generation.setRunner(actualRunner);
-        if (preservation != null) {
-            preservation.register(actualRunner);
-        }
-        return generation;
+    private static int outputHeight(Request request) {
+        return Math.max(1, (request.height() + request.sampleStep() - 1) / request.sampleStep());
     }
 
     private static RenderStats combine(BandStats[] bands) {
@@ -304,12 +256,12 @@ final class NoiseRenderCoordinator implements AutoCloseable {
         void onRenderFailed(Request request, Throwable error);
     }
 
-    record Request(long revision, NoiseProvider sampler, NoiseViewport viewport, NoisePalette palette,
+    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(palette, "palette");
+            Objects.requireNonNull(colorScale, "colorScale");
             if (revision < 0L || width < 1 || height < 1 || sampleStep < 1) {
                 throw new IllegalArgumentException("Invalid noise render request");
             }
@@ -322,36 +274,69 @@ final class NoiseRenderCoordinator implements AutoCloseable {
 
     private static final class RenderGeneration {
         private final Request request;
-        private final ThreadPoolExecutor executor;
-        private volatile Thread runner;
+        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, ThreadPoolExecutor executor) {
-            this.request = Objects.requireNonNull(request, "request");
-            this.executor = Objects.requireNonNull(executor, "executor");
+        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 ThreadPoolExecutor executor() {
-            return executor;
+        private int bandCount() {
+            return bandStats.length;
         }
 
-        private void setRunner(Thread runner) {
-            this.runner = Objects.requireNonNull(runner, "runner");
+        private int outputWidth() {
+            return outputWidth;
         }
 
-        private void start() {
-            runner.start();
+        private int outputHeight() {
+            return outputHeight;
         }
 
-        private void close() {
-            Thread activeRunner = runner;
-            if (activeRunner != null) {
-                activeRunner.interrupt();
-            }
-            executor.shutdownNow();
+        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 = MapHost.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);
         }
     }
 

core/src/main/java/art/arcane/iris/studio/map/NoiseTerrain.java

@@ -0,0 +1,98 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.Arrays;
+
+/**
+ * A stretch of noise or world as terrain at Minecraft scale: one height in blocks and one colour per column, each column
+ * {@code step} blocks wide and deep. Columns without a valid value are left out.
+ */
+record NoiseTerrain(int originX, int originZ, int columns, int rows, int step, float[] heights, int[] colors,
+                    double lowest, double highest) {
+    /**
+     * Samples every column of the grid.
+     */
+    static NoiseTerrain sample(TerrainSampling sampling, TerrainGrid grid) {
+        float[] heights = new float[grid.columns() * grid.rows()];
+        int[] colors = new int[heights.length];
+        for (int row = 0; row < grid.rows(); row++) {
+            sampling.columns().sampleRow(grid, row, heights, colors);
+        }
+        return of(grid, heights, colors);
+    }
+
+    static NoiseTerrain empty(TerrainGrid grid) {
+        float[] heights = new float[grid.columns() * grid.rows()];
+        Arrays.fill(heights, Float.NaN);
+        return of(grid, heights, new int[heights.length]);
+    }
+
+    private static NoiseTerrain of(TerrainGrid grid, float[] heights, int[] colors) {
+        double lowest = Double.NaN;
+        double highest = Double.NaN;
+        for (float height : heights) {
+            if (Float.isNaN(height)) {
+                continue;
+            }
+            lowest = Double.isNaN(lowest) ? height : Math.min(lowest, height);
+            highest = Double.isNaN(highest) ? height : Math.max(highest, height);
+        }
+        return new NoiseTerrain(grid.originX(), grid.originZ(), grid.columns(), grid.rows(), grid.step(), heights, colors,
+                lowest, highest);
+    }
+
+    boolean hasHeight(int column, int row) {
+        return column >= 0 && row >= 0 && column < columns && row < rows && !Float.isNaN(heights[row * columns + column]);
+    }
+
+    float height(int column, int row) {
+        return heights[row * columns + column];
+    }
+
+    int color(int column, int row) {
+        return colors[row * columns + column];
+    }
+
+    // The world position of a column's or row's first block.
+    double worldX(double column) {
+        return originX + column * step;
+    }
+
+    double worldZ(double row) {
+        return originZ + row * step;
+    }
+
+    int sizeX() {
+        return columns * step;
+    }
+
+    int sizeZ() {
+        return rows * step;
+    }
+
+    boolean isEmpty() {
+        return Double.isNaN(lowest);
+    }
+
+    // A block below the lowest point, where sides on the terrain's edge end.
+    int baseY() {
+        return (int) Math.floor(lowest) - 1;
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/NoiseTerrainRenderer.java

@@ -0,0 +1,440 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.awt.image.BufferedImage;
+import java.awt.image.DataBufferInt;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+/**
+ * Draws noise terrain without a graphics card. Block columns get Minecraft's face shading and an outline around every
+ * block, until blocks get too small on screen to outline. Noise measured in blocks gets see-through water up to its
+ * level.
+ * <p>
+ * Each frame is split into horizontal bands drawn side by side, every band drawing only the pixels in its rows. Block
+ * faces are found once per terrain; each frame only works out which rows they cover, so bands skip the rest cheaply.
+ */
+final class NoiseTerrainRenderer {
+    private static final double TOP_SHADE = 1D;
+    private static final double NORTH_SOUTH_SHADE = 0.8D;
+    private static final double EAST_WEST_SHADE = 0.6D;
+    private static final double LEAST_SIDE_CONTRAST = 0.35D;
+    // The graphics card draws with these too, so both look alike.
+    static final int WATER_COLOR = 0x3F76E4;
+    static final double WATER_OPACITY = 0.55D;
+    static final double OUTLINE_SHADE = 0.72D;
+    static final double OUTLINE_LIGHTENING = 0.25D;
+    static final double DARK_LUMINANCE = 70D;
+    static final double LEAST_OUTLINE_SPACING_PIXELS = 4D;
+    static final double FULL_OUTLINE_SPACING_PIXELS = 12D;
+    static final double OUTLINE_HALF_WIDTH_PIXELS = 0.5D;
+    // A few slices per worker even out slices that take longer, like bands crossing the busiest part of the terrain.
+    private static final int SLICES_PER_WORKER = 2;
+    // Shared 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;
+
+    private final TerrainLayer layer;
+    private final NoiseTerrain terrain;
+    private final OrbitProjection projection;
+    private final int width;
+    private final int[] pixels;
+    private final double[] depths;
+    private final FaceRows faceRows;
+    private final int bandTop;
+    private final int bandBottom;
+    private final int[] runColors;
+
+    private NoiseTerrainRenderer(Frame frame, TerrainLayer layer, FaceRows faceRows, int bandTop, int bandBottom) {
+        this.layer = layer;
+        this.terrain = layer.terrain();
+        this.projection = frame.projection();
+        this.width = frame.width();
+        this.pixels = frame.pixels();
+        this.depths = frame.depths();
+        this.faceRows = faceRows;
+        this.bandTop = bandTop;
+        this.bandBottom = bandBottom;
+        this.runColors = new int[Math.max(terrain.columns(), terrain.rows())];
+    }
+
+    static OrbitPicture render(NoiseTerrainScene scene, OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        BufferedImage image = new BufferedImage(Math.max(1, width), Math.max(1, height), BufferedImage.TYPE_INT_RGB);
+        Frame frame = Frame.of(image, scene, camera, coveredLeftWidth);
+        List<FaceRows> faceRows = new ArrayList<>(scene.layers().size());
+        for (HoledLayer layer : scene.layers()) {
+            faceRows.add(FaceRows.of(frame, layer.layer(), layer.holeOfAllFillers(), scene));
+        }
+        inSlices(image.getHeight(), scene, (top, bottom) -> drawBand(frame, scene, faceRows, top, bottom - 1));
+        return OrbitPicture.of(image, frame.depths(), frame.projection());
+    }
+
+    // Every layer draws what it has in the band's rows; the water goes over all of them last.
+    private static void drawBand(Frame frame, NoiseTerrainScene scene, List<FaceRows> faceRows, int bandTop, int bandBottom) {
+        frame.clearRows(bandTop, bandBottom);
+        for (int layer = 0; layer < scene.layers().size(); layer++) {
+            new NoiseTerrainRenderer(frame, scene.layers().get(layer).layer(), faceRows.get(layer), bandTop, bandBottom).drawBlocks();
+        }
+        if (scene.hasWater() && !scene.layers().isEmpty()) {
+            NoiseTerrainScene.Extent extent = scene.extent();
+            new NoiseTerrainRenderer(frame, scene.layers().get(0).layer(), FaceRows.NONE, bandTop, bandBottom)
+                    .drawWater(extent.minX(), extent.minZ(), extent.sizeX(), extent.sizeZ(), BlockFaces.blockTop(scene.waterLevel()));
+        }
+    }
+
+    // Splits {@code total} items into a few slices per worker and works on them side by side.
+    private static void inSlices(int total, NoiseTerrainScene scene, SliceWork work) {
+        int sliceCount = Math.min(total, scene.workerCount() * SLICES_PER_WORKER);
+        List<Callable<Void>> slices = new ArrayList<>(sliceCount);
+        for (int slice = 0; slice < sliceCount; slice++) {
+            int from = total * slice / sliceCount;
+            int to = total * (slice + 1) / sliceCount;
+            slices.add(() -> {
+                work.doSlice(from, to);
+                return null;
+            });
+        }
+        try {
+            for (Future<Void> slice : scene.workers().invokeAll(slices)) {
+                slice.get();
+            }
+        } catch (InterruptedException interrupted) {
+            Thread.currentThread().interrupt();
+        } catch (ExecutionException error) {
+            throw new IllegalStateException("Drawing the terrain failed", error.getCause());
+        }
+    }
+
+    private void drawBlocks() {
+        BlockFaces faces = layer.faces();
+        for (int face = 0; face < faces.count(); face++) {
+            if (faceRows.crosses(face, bandTop, bandBottom)) {
+                drawFace(faces, face);
+            }
+        }
+    }
+
+    // A face stretching over several columns is still coloured and outlined column by column.
+    private void drawFace(BlockFaces faces, int face) {
+        BlockFaces.Facing facing = faces.facing(face);
+        double shade = faceShadeAt(facing, projection.pixelsPerBlock());
+        int columns = faces.columns(face);
+        for (int along = 0; along < columns; along++) {
+            int column = faces.firstColumn(face) + (facing.runsAlongX() ? along : 0);
+            int row = faces.firstRow(face) + (facing.runsAlongX() ? 0 : along);
+            runColors[along] = shade(terrain.color(column, row), shade);
+        }
+        fillQuad(faces.originX(face), faces.originY(face), faces.originZ(face), faces.runX(face), 0D, faces.runZ(face),
+                0D, faces.reachY(face), faces.reachZ(face), facing.normalX, facing.normalY, facing.normalZ,
+                runColors, columns, faces.height(face));
+    }
+
+    // How much a face's colour is darkened, with blocks drawn {@code pixelsPerBlock} wide.
+    static double faceShadeAt(BlockFaces.Facing facing, double pixelsPerBlock) {
+        return withContrast(faceShade(facing), blockSideContrast(pixelsPerBlock));
+    }
+
+    private static double faceShade(BlockFaces.Facing facing) {
+        return switch (facing) {
+            case TOP -> TOP_SHADE;
+            case NORTH, SOUTH -> NORTH_SOUTH_SHADE;
+            case WEST, EAST -> EAST_WEST_SHADE;
+        };
+    }
+
+    // Blocks a few pixels wide show their sides as one-pixel slivers on every slope; at full contrast those read as noise.
+    private static double blockSideContrast(double pixelsPerBlock) {
+        return LEAST_SIDE_CONTRAST + (1D - LEAST_SIDE_CONTRAST) * outlineStrength(pixelsPerBlock);
+    }
+
+    private static double withContrast(double faceShade, double contrast) {
+        return 1D - (1D - faceShade) * contrast;
+    }
+
+    // Water is drawn last, blended over whatever lies below its surface, without hiding what is behind it.
+    private void drawWater(double x, double z, double sizeX, double sizeZ, double level) {
+        Footprint water = new Footprint(x, level, z, sizeX, 0, 0, 0, 0, sizeZ);
+        if (water.isEmpty()) {
+            return;
+        }
+        for (int y = water.top; y <= water.bottom; y++) {
+            water.spanRow(y);
+            for (int pixelX = water.rowStart; pixelX <= water.rowEnd; pixelX++) {
+                double alongU = water.alongU(pixelX, y);
+                double alongV = water.alongV(pixelX, y);
+                int index = y * width + pixelX;
+                if (isInside(alongU, alongV) && water.depthAt(alongU, alongV) > depths[index]) {
+                    pixels[index] = blend(WATER_COLOR, pixels[index], WATER_OPACITY);
+                }
+            }
+        }
+    }
+
+    /**
+     * Fills the parallelogram from {@code origin} along both edges, with lines {@code 1 / units} of the way along
+     * each edge; no lines when {@code units} is 0. Each of the {@code unitsU} blocks along the first edge takes its
+     * colour from {@code colorsAlongU}; with no units, the whole face takes the first.
+     */
+    private void fillQuad(double originX, double originY, double originZ, double uX, double uY, double uZ,
+                          double vX, double vY, double vZ, int normalX, int normalY, int normalZ,
+                          int[] colorsAlongU, int unitsU, int unitsV) {
+        if (!projection.facesCamera(normalX, normalY, normalZ)) {
+            return;
+        }
+        Footprint quad = new Footprint(originX, originY, originZ, uX, uY, uZ, vX, vY, vZ);
+        if (quad.isEmpty()) {
+            return;
+        }
+        double pixelsPerUnitU = unitsU == 0 ? 0D : quad.lengthU() / unitsU;
+        double pixelsPerUnitV = unitsV == 0 ? 0D : quad.lengthV() / unitsV;
+        double outlineStrengthU = outlineStrength(pixelsPerUnitU);
+        double outlineStrengthV = outlineStrength(pixelsPerUnitV);
+        int lastUnitU = Math.max(0, unitsU - 1);
+        for (int y = quad.top; y <= quad.bottom; y++) {
+            quad.spanRow(y);
+            for (int x = quad.rowStart; x <= quad.rowEnd; x++) {
+                double alongU = quad.alongU(x, y);
+                double alongV = quad.alongV(x, y);
+                if (!isInside(alongU, alongV)) {
+                    continue;
+                }
+                int index = y * width + x;
+                double depth = quad.depthAt(alongU, alongV);
+                if (depth < depths[index]) {
+                    continue;
+                }
+                depths[index] = depth;
+                int color = colorsAlongU[Math.max(0, Math.min(lastUnitU, (int) (alongU * unitsU)))];
+                if (isOnLine(alongU, unitsU, pixelsPerUnitU)) {
+                    pixels[index] = blend(outlineOf(color), color, outlineStrengthU);
+                } else if (isOnLine(alongV, unitsV, pixelsPerUnitV)) {
+                    pixels[index] = blend(outlineOf(color), color, outlineStrengthV);
+                } else {
+                    pixels[index] = color;
+                }
+            }
+        }
+    }
+
+    private static boolean isInside(double alongU, double alongV) {
+        return alongU >= -EDGE_TOLERANCE && alongU <= 1D + EDGE_TOLERANCE && alongV >= -EDGE_TOLERANCE && alongV <= 1D + EDGE_TOLERANCE;
+    }
+
+    // Lines fade in as blocks grow on screen; dense lines at full strength would only speckle the face.
+    private static double outlineStrength(double pixelsPerUnit) {
+        double fadeIn = (pixelsPerUnit - LEAST_OUTLINE_SPACING_PIXELS) / (FULL_OUTLINE_SPACING_PIXELS - LEAST_OUTLINE_SPACING_PIXELS);
+        return Math.max(0D, Math.min(1D, fadeIn));
+    }
+
+    // Lines closer together than a few pixels would only grey the face out, so they are left out.
+    private static boolean isOnLine(double along, int units, double pixelsPerUnit) {
+        if (pixelsPerUnit < LEAST_OUTLINE_SPACING_PIXELS) {
+            return false;
+        }
+        double unitsAlong = along * units;
+        return Math.abs(unitsAlong - Math.rint(unitsAlong)) * pixelsPerUnit < OUTLINE_HALF_WIDTH_PIXELS;
+    }
+
+    // Dark faces get lighter outlines, so the blocks of a black low still show.
+    private static int outlineOf(int color) {
+        double luminance = 0.3D * ((color >>> 16) & 0xFF) + 0.59D * ((color >>> 8) & 0xFF) + 0.11D * (color & 0xFF);
+        return luminance < DARK_LUMINANCE ? blend(0xFFFFFF, color, OUTLINE_LIGHTENING) : shade(color, OUTLINE_SHADE);
+    }
+
+    private static int shade(int color, double shade) {
+        return BlockPreviewColors.shade(color, shade);
+    }
+
+    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));
+    }
+
+    /**
+     * What every band of one frame shares: the image's pixels and depths, and where the terrain lands on it.
+     */
+    private record Frame(OrbitProjection projection, int width, int[] pixels, double[] depths) {
+        static Frame of(BufferedImage image, NoiseTerrainScene scene, OrbitCamera camera, int coveredLeftWidth) {
+            OrbitProjection projection = scene.projection(camera, image.getWidth(), image.getHeight(), coveredLeftWidth);
+            int[] pixels = ((DataBufferInt) image.getRaster().getDataBuffer()).getData();
+            return new Frame(projection, image.getWidth(), pixels, new double[pixels.length]);
+        }
+
+        void clearRows(int top, int bottom) {
+            int from = top * width;
+            int to = (bottom + 1) * width;
+            Arrays.fill(pixels, from, to, StudioTheme.EDITOR_BACKGROUND.getRGB() & 0xFFFFFF);
+            Arrays.fill(depths, from, to, Double.NEGATIVE_INFINITY);
+        }
+    }
+
+    /**
+     * The screen rows each block face of a layer spans this frame, worked out once so every band skips the faces it
+     * doesn't cross without projecting them again.
+     */
+    private record FaceRows(int[] tops, int[] bottoms) {
+        static final FaceRows NONE = new FaceRows(new int[0], new int[0]);
+
+        static FaceRows of(Frame frame, TerrainLayer layer, TerrainHole hole, NoiseTerrainScene scene) {
+            BlockFaces faces = layer.faces();
+            FaceRows rows = new FaceRows(new int[faces.count()], new int[faces.count()]);
+            inSlices(faces.count(), scene, (from, to) -> rows.measure(faces, hole, frame.projection(), from, to));
+            return rows;
+        }
+
+        // Faces looking away from the camera, or not showing with the hole, are never drawn, so they span no rows.
+        private void measure(BlockFaces faces, TerrainHole hole, OrbitProjection projection, int fromFace, int toFace) {
+            for (int face = fromFace; face < toFace; face++) {
+                BlockFaces.Facing facing = faces.facing(face);
+                if (!projection.facesCamera(facing.normalX, facing.normalY, facing.normalZ) || !hole.shows(faces, face)) {
+                    tops[face] = Integer.MAX_VALUE;
+                    bottoms[face] = Integer.MIN_VALUE;
+                    continue;
+                }
+                double originY = projection.screenY(faces.originX(face), faces.originY(face), faces.originZ(face));
+                double runY = projection.screenStepY(faces.runX(face), 0D, faces.runZ(face));
+                double reachY = projection.screenStepY(0D, faces.reachY(face), faces.reachZ(face));
+                tops[face] = (int) Math.floor(originY + Math.min(0D, runY) + Math.min(0D, reachY));
+                bottoms[face] = (int) Math.ceil(originY + Math.max(0D, runY) + Math.max(0D, reachY));
+            }
+        }
+
+        boolean crosses(int face, int top, int bottom) {
+            return tops[face] <= bottom && bottoms[face] >= top;
+        }
+    }
+
+    @FunctionalInterface
+    private interface SliceWork {
+        void doSlice(int from, int to);
+    }
+
+    /**
+     * Where a parallelogram, from an origin along two edges, lands in this band: the pixels around it, and how far
+     * along each edge, and how near, any pixel inside it is.
+     */
+    private final class Footprint {
+        private final double originX;
+        private final double originY;
+        private final double originDepth;
+        private final double edgeUX;
+        private final double edgeUY;
+        private final double edgeUDepth;
+        private final double edgeVX;
+        private final double edgeVY;
+        private final double edgeVDepth;
+        private final double determinant;
+        private final int left;
+        private final int right;
+        private final int top;
+        private final int bottom;
+        private int rowStart;
+        private int rowEnd;
+
+        private Footprint(double x, double y, double z, double uX, double uY, double uZ, double vX, double vY, double vZ) {
+            originX = projection.screenX(x, y, z);
+            originY = projection.screenY(x, y, z);
+            originDepth = projection.depth(x, y, z);
+            edgeUX = projection.screenStepX(uX, uZ);
+            edgeUY = projection.screenStepY(uX, uY, uZ);
+            edgeUDepth = projection.depthStep(uX, uY, uZ);
+            edgeVX = projection.screenStepX(vX, vZ);
+            edgeVY = projection.screenStepY(vX, vY, vZ);
+            edgeVDepth = projection.depthStep(vX, vY, vZ);
+            determinant = edgeUX * edgeVY - edgeUY * edgeVX;
+            left = Math.max(0, (int) Math.floor(min(originX, originX + edgeUX, originX + edgeVX, originX + edgeUX + edgeVX)));
+            right = Math.min(width - 1, (int) Math.ceil(max(originX, originX + edgeUX, originX + edgeVX, originX + edgeUX + edgeVX)));
+            top = Math.max(bandTop, (int) Math.floor(min(originY, originY + edgeUY, originY + edgeVY, originY + edgeUY + edgeVY)));
+            bottom = Math.min(bandBottom, (int) Math.ceil(max(originY, originY + edgeUY, originY + edgeVY, originY + edgeUY + edgeVY)));
+        }
+
+        // Edge-on faces cover no pixels, and faces outside the band are another band's work.
+        private boolean isEmpty() {
+            return Math.abs(determinant) < EDGE_ON_DETERMINANT || top > bottom || left > right;
+        }
+
+        /**
+         * Narrows {@link #rowStart} to {@link #rowEnd} to the pixels of row {@code y} the footprint can cover, so long
+         * thin faces lying across the screen don't cost their whole bounding box. A pixel or so either side is kept;
+         * the caller still tests every pixel.
+         */
+        private void spanRow(int y) {
+            double fromOriginY = y + 0.5D - originY;
+            double slopeU = edgeVY / determinant;
+            double startU = -fromOriginY * edgeVX / determinant;
+            double slopeV = -edgeUY / determinant;
+            double startV = fromOriginY * edgeUX / determinant;
+            double[] range = {Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY};
+            keepWhere(range, slopeU, startU, 0D, 1D);
+            keepWhere(range, slopeV, startV, 0D, 1D);
+            rowStart = Math.max(left, (int) Math.floor(range[0] + originX - 0.5D));
+            rowEnd = Math.min(right, (int) Math.ceil(range[1] + originX - 0.5D));
+        }
+
+        // Narrows the range of offsets from the origin to where {@code start + slope * offset} stays within the limits.
+        private static void keepWhere(double[] range, double slope, double start, double lowest, double highest) {
+            if (Math.abs(slope) < EDGE_ON_DETERMINANT) {
+                if (start < lowest - EDGE_TOLERANCE || start > highest + EDGE_TOLERANCE) {
+                    range[0] = Double.POSITIVE_INFINITY;
+                }
+                return;
+            }
+            double atLowest = (lowest - EDGE_TOLERANCE - start) / slope;
+            double atHighest = (highest + EDGE_TOLERANCE - start) / slope;
+            range[0] = Math.max(range[0], Math.min(atLowest, atHighest));
+            range[1] = Math.min(range[1], Math.max(atLowest, atHighest));
+        }
+
+        private double alongU(int x, int y) {
+            return ((x + 0.5D - originX) * edgeVY - (y + 0.5D - originY) * edgeVX) / determinant;
+        }
+
+        private double alongV(int x, int y) {
+            return ((y + 0.5D - originY) * edgeUX - (x + 0.5D - originX) * edgeUY) / determinant;
+        }
+
+        private double depthAt(double alongU, double alongV) {
+            return originDepth + alongU * edgeUDepth + alongV * edgeVDepth;
+        }
+
+        private double lengthU() {
+            return Math.hypot(edgeUX, edgeUY);
+        }
+
+        private double lengthV() {
+            return Math.hypot(edgeVX, edgeVY);
+        }
+
+        private static double min(double a, double b, double c, double d) {
+            return Math.min(Math.min(a, b), Math.min(c, d));
+        }
+
+        private static double max(double a, double b, double c, double d) {
+            return Math.max(Math.max(a, b), Math.max(c, d));
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/NoiseTerrainScene.java

@@ -0,0 +1,139 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.ExecutorService;
+
+/**
+ * Endless noise terrain as the orbit viewport shows it: the tiles in sight as block columns, drawn by
+ * {@code workerCount} of {@code workers} at once on machines without a graphics card. The camera's pivot is given
+ * from {@code anchor}, and zoom sets pixels per block directly, so tiles coming and going never move the view.
+ *
+ * @param floorY     where sides on the edge of the sampled ground end
+ * @param waterLevel the height water fills up to, or NaN when the noise has no water
+ */
+record NoiseTerrainScene(List<HoledLayer> layers, Vec3 anchor, int floorY, int topY, double waterLevel,
+                         ExecutorService workers, int workerCount) implements OrbitScene {
+    // Looks further down than the object viewer, so a landscape's shape reads before its sides.
+    static final OrbitCamera START = new OrbitCamera(0.76D, 0.62D, 1D, Vec3.ZERO);
+    private static final double VIEW_HEIGHT_BLOCKS_AT_ZOOM_ONE = 384D;
+    // Looking level would see endless ground, and looking up only its underside.
+    private static final double LOWEST_PITCH = 0.1D;
+    private static final double HIGHEST_PITCH = 1.3D;
+    private static final double TALLEST_VIEW_BLOCKS = 100_000D;
+    private static final double SHORTEST_VIEW_BLOCKS = 24D;
+    private static final OrbitLimits LIMITS = new OrbitLimits(LOWEST_PITCH, HIGHEST_PITCH,
+            VIEW_HEIGHT_BLOCKS_AT_ZOOM_ONE / TALLEST_VIEW_BLOCKS, VIEW_HEIGHT_BLOCKS_AT_ZOOM_ONE / SHORTEST_VIEW_BLOCKS);
+
+    static OrbitProjection projectionFrom(Vec3 anchor, OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        int covered = Math.max(0, Math.min(width - 1, coveredLeftWidth));
+        return OrbitProjection.atScale(anchor, camera, height / VIEW_HEIGHT_BLOCKS_AT_ZOOM_ONE, width, height, covered);
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return layers.stream().allMatch(layer -> layer.terrain().isEmpty());
+    }
+
+    @Override
+    public OrbitCamera startingCamera() {
+        return START;
+    }
+
+    @Override
+    public OrbitLimits limits() {
+        return LIMITS;
+    }
+
+    @Override
+    public OrbitPicture render(OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        return renderOnCard(camera, width, height, coveredLeftWidth)
+                .orElseGet(() -> NoiseTerrainRenderer.render(this, camera, width, height, coveredLeftWidth));
+    }
+
+    private Optional<OrbitPicture> renderOnCard(OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        if (!GpuLibrary.isLoaded()) {
+            return Optional.empty();
+        }
+        return GpuTerrainRenderer.render(this, camera, width, height, coveredLeftWidth);
+    }
+
+    @Override
+    public boolean canRenderOnScreen() {
+        return GpuLibrary.isLoaded() && GpuFrames.canDrawOnScreen();
+    }
+
+    @Override
+    public Optional<OrbitPicture> renderOnScreen(ScreenTarget screen, OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        return GpuTerrainRenderer.renderOnScreen(this, screen, camera, width, height, coveredLeftWidth);
+    }
+
+    @Override
+    public OrbitProjection projection(OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        return projectionFrom(anchor, camera, width, height, coveredLeftWidth);
+    }
+
+    boolean hasWater() {
+        return Double.isFinite(waterLevel) && waterLevel > floorY;
+    }
+
+    /**
+     * Where the layers lie, from the floor to the highest ground, so water can spread under all of them.
+     */
+    Extent extent() {
+        double minX = Double.POSITIVE_INFINITY;
+        double minZ = Double.POSITIVE_INFINITY;
+        double maxX = Double.NEGATIVE_INFINITY;
+        double maxZ = Double.NEGATIVE_INFINITY;
+        double lowest = floorY;
+        double highest = topY;
+        for (HoledLayer layer : layers) {
+            NoiseTerrain terrain = layer.terrain();
+            minX = Math.min(minX, terrain.originX());
+            minZ = Math.min(minZ, terrain.originZ());
+            maxX = Math.max(maxX, terrain.originX() + (double) terrain.sizeX());
+            maxZ = Math.max(maxZ, terrain.originZ() + (double) terrain.sizeZ());
+            if (!terrain.isEmpty()) {
+                lowest = Math.min(lowest, terrain.baseY());
+                highest = Math.max(highest, BlockFaces.blockTop(terrain.highest()));
+            }
+        }
+        return new Extent(minX, lowest, minZ, maxX, highest, maxZ);
+    }
+
+    record Extent(double minX, double minY, double minZ, double maxX, double maxY, double maxZ) {
+        double sizeX() {
+            return maxX - minX;
+        }
+
+        double sizeZ() {
+            return maxZ - minZ;
+        }
+
+        // The farthest any of it lies from a point, which the depth buffer has to reach.
+        double farthestFrom(Vec3 point) {
+            double x = Math.max(Math.abs(minX - point.x()), Math.abs(maxX - point.x()));
+            double y = Math.max(Math.abs(minY - point.y()), Math.abs(maxY - point.y()));
+            double z = Math.max(Math.abs(minZ - point.z()), Math.abs(maxZ - point.z()));
+            return Math.sqrt(x * x + y * y + z * z);
+        }
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/NoiseTerrainView.java

@@ -0,0 +1,216 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.spi.IrisLogging;
+
+import java.awt.EventQueue;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * What the 3D noise view shows: endless terrain, sampled tile by tile wherever the camera looks. Whenever the camera
+ * moves or another tile is sampled, what to draw is worked out again off the Swing thread.
+ */
+final class NoiseTerrainView {
+    private final OrbitViewport viewport;
+    private final ExecutorService renderWorkers;
+    private final ExecutorService samplers;
+    private final int workerCount;
+    private final ExecutorService coverer = Executors.newSingleThreadExecutor(task -> {
+        Thread thread = new Thread(task, "Iris Noise Terrain Cover");
+        thread.setDaemon(true);
+        return thread;
+    });
+    private final AtomicBoolean coverQueued = new AtomicBoolean();
+    private volatile TerrainTiles tiles;
+    private volatile Vec3 anchor;
+    private volatile ViewState view;
+    private volatile boolean hidden = true;
+    private double centerX;
+    private double centerZ;
+    private boolean recentered = true;
+    private TerrainCover.Result shown;
+    private Runnable onProgress = () -> {
+    };
+
+    NoiseTerrainView(OrbitViewport viewport, ExecutorService renderWorkers, ExecutorService samplers, int workerCount) {
+        this.viewport = viewport;
+        this.renderWorkers = renderWorkers;
+        this.samplers = samplers;
+        this.workerCount = workerCount;
+        viewport.onViewChange(this::viewChanged);
+    }
+
+    /**
+     * Shows the ground around this point next, turning around it.
+     */
+    void centerOn(double worldX, double worldZ) {
+        centerX = worldX;
+        centerZ = worldZ;
+        recentered = true;
+        if (viewport.isShowingScene()) {
+            viewport.centerPivot();
+        }
+    }
+
+    /**
+     * Samples the terrain anew, as the camera looks at it, keeping the camera if the view already shows some. The ground
+     * shown so far stays until its tiles are sampled anew.
+     */
+    void show(TerrainSampling sampling) {
+        if (recentered || anchor == null) {
+            anchor = new Vec3(centerX, (sampling.floorY() + sampling.topY()) / 2D, centerZ);
+            recentered = false;
+        }
+        TerrainTiles previous = tiles;
+        Map<TerrainTile, TerrainLayer> shownBefore = previous == null ? Map.of() : previous.layersInUse();
+        if (previous != null) {
+            previous.close();
+        }
+        tiles = new TerrainTiles(sampling, samplers, workerCount, this::requestCover, shownBefore);
+        hidden = false;
+        viewChanged();
+    }
+
+    /**
+     * Goes on sampling what the camera looks at after {@link #hide}, with the tiles sampled before.
+     */
+    void resume() {
+        if (tiles == null) {
+            return;
+        }
+        hidden = false;
+        viewChanged();
+    }
+
+    // Nothing is sampled for a view no one sees.
+    void hide() {
+        hidden = true;
+        TerrainTiles current = tiles;
+        if (current != null) {
+            current.sampleOnly(List.of(), Set.of());
+        }
+    }
+
+    /**
+     * @param listener runs on the Swing thread whenever the detail wanted or the tiles still to sample change
+     */
+    void onProgress(Runnable listener) {
+        onProgress = listener;
+    }
+
+    // How many blocks wide the columns are that the view wants, or 0 before anything was worked out.
+    int detailStep() {
+        return shown == null ? 0 : shown.detailStep();
+    }
+
+    int pendingTiles() {
+        return shown == null ? 0 : shown.pendingTiles();
+    }
+
+    /**
+     * How the view looks at the ground for its newest camera, or null before it has any ground to look at.
+     */
+    GroundSight groundSight() {
+        TerrainTiles current = tiles;
+        ViewState state = view;
+        Vec3 at = anchor;
+        if (current == null || state == null || at == null || state.width() < 1 || state.height() < 1) {
+            return null;
+        }
+        OrbitProjection projection = NoiseTerrainScene.projectionFrom(at, state.camera(), state.width(), state.height(), state.coveredLeftWidth());
+        TerrainSampling sampling = current.sampling();
+        int left = Math.max(0, Math.min(state.width() - 1, state.coveredLeftWidth()));
+        return new GroundSight(projection, left, state.width(), state.height(), sampling.floorY(), sampling.topY());
+    }
+
+    void close() {
+        coverer.shutdownNow();
+        TerrainTiles current = tiles;
+        if (current != null) {
+            current.close();
+        }
+    }
+
+    // Before the first scene, the viewport still holds whatever camera it had; the scene will start it afresh.
+    private void viewChanged() {
+        OrbitCamera camera = viewport.isShowingScene() ? viewport.camera() : NoiseTerrainScene.START;
+        view = new ViewState(camera, viewport.getWidth(), viewport.getHeight(), viewport.coveredLeftWidth());
+        requestCover();
+    }
+
+    // Requests while one waits to start are one and the same: it will see the newest view and tiles anyway.
+    private void requestCover() {
+        if (coverQueued.getAndSet(true)) {
+            return;
+        }
+        coverer.execute(() -> {
+            coverQueued.set(false);
+            coverSafely();
+        });
+    }
+
+    private void coverSafely() {
+        try {
+            cover();
+        } catch (RuntimeException error) {
+            IrisLogging.reportError(error);
+        }
+    }
+
+    private void cover() {
+        TerrainTiles current = tiles;
+        ViewState state = view;
+        Vec3 at = anchor;
+        if (hidden || current == null || state == null || at == null || state.width() < 1 || state.height() < 1) {
+            return;
+        }
+        OrbitProjection projection = NoiseTerrainScene.projectionFrom(at, state.camera(), state.width(), state.height(), state.coveredLeftWidth());
+        TerrainCover.Result result = TerrainCover.of(current, projection, state.width(), state.height(), state.coveredLeftWidth());
+        TerrainSampling sampling = current.sampling();
+        NoiseTerrainScene scene = new NoiseTerrainScene(result.layers(), at, sampling.floorY(), sampling.topY(),
+                sampling.waterLevel(), renderWorkers, workerCount);
+        EventQueue.invokeLater(() -> showCovered(current, scene, result));
+    }
+
+    // Until any ground is sampled, the view keeps what it showed before, or its loading animation.
+    private void showCovered(TerrainTiles coveredTiles, NoiseTerrainScene scene, TerrainCover.Result result) {
+        if (coveredTiles != tiles) {
+            return;
+        }
+        shown = result;
+        onProgress.run();
+        if (scene.isEmpty() && result.pendingTiles() > 0) {
+            return;
+        }
+        if (viewport.isShowingScene()) {
+            viewport.replaceScene(scene);
+        } else {
+            viewport.show(scene);
+        }
+    }
+
+    private record ViewState(OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/NoiseViewport.java

@@ -1,4 +1,22 @@
-package art.arcane.iris.studio.view;
+/*
+ * 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 art.arcane.iris.studio.map;
 
 record NoiseViewport(double centerX, double centerZ, double blocksPerPixel) {
     static final double MIN_BLOCKS_PER_PIXEL = 0.0001D;
@@ -21,6 +39,14 @@ record NoiseViewport(double centerX, double centerZ, double blocksPerPixel) {
         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),

core/src/main/java/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/ObjectExplorer.java

@@ -0,0 +1,566 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.BlockTextures.BlockTexture;
+import art.arcane.iris.pack.loading.IrisData;
+import art.arcane.iris.generation.runtime.Engine;
+import art.arcane.iris.structure.object.IrisObject;
+import art.arcane.iris.generation.geometry.IrisBlockVector;
+import art.arcane.volmlib.nativelib.terrain.NativeBlockState;
+
+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 String TINT_BIOME = "minecraft:plains";
+    private static final int UNKNOWN_BLOCK_COLOR = 0x8A8A8A;
+    private static final String CAMERA_HINT = "Drag to orbit · Right-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 OrbitViewport viewport = new OrbitViewport("Iris Object Viewer", "Choose an object");
+    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;
+    private final StudioStatusBar statusBar = new StudioStatusBar();
+    private final LatestMeasurement<BakeTiming> bakeTimer = new LatestMeasurement<>("Iris Bake Timer");
+    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);
+        this.overview = new ObjectOverviewPanel(this::showSeeThrough, source.isBaked());
+        views.add(layerCut.floatingOver(viewport), ONE_VARIANT_CARD);
+        views.add(gallery, ALL_VARIANTS_CARD);
+        this.viewWithOverlays = variantPicker.floatingOver(views);
+        MapHost.interruptOnPluginShutdown(loader);
+        MapHost.interruptOnPluginShutdown(thumbnailPainter);
+        MapHost.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() {
+        MapHost.unregisterHotloadHook(hotloadHook);
+        objectRevision.incrementAndGet();
+        loader.shutdownNow();
+        thumbnailPainter.shutdownNow();
+        bakeTimer.close();
+        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());
+            bakeTimer.discardPending();
+            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);
+                timeBake(data, key, seed);
+            });
+        } catch (RuntimeException error) {
+            EventQueue.invokeLater(() -> showFailure(revision, key, error));
+        }
+    }
+
+    // Off the loader thread, so stepping through variants and seeds never waits on the timing.
+    private void timeBake(IrisData data, String key, OptionalLong seed) {
+        if (!source.isBaked() || seed.isEmpty()) {
+            return;
+        }
+        long bakedSeed = seed.getAsLong();
+        overview.showTimingBake();
+        bakeTimer.measureUntilSuperseded(stillWanted -> BakeTiming.measure(() -> source.timeBake(data, key, bakedSeed), stillWanted),
+                overview::showBakeTiming);
+    }
+
+    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<IrisBlockVector, NativeBlockState> blocks = visibleBlocks(object);
+        ObjectMesh.Bounds extent = ObjectMesh.Bounds.of(blocks.keySet());
+        ObjectMesh.Bounds bounds = source.groundY(object).stream().mapToObj(extent::standingOn).findFirst().orElse(extent);
+        ObjectMesh mesh = ObjectMesh.build(blocks, this::modelOf, bounds, block -> false);
+        ObjectSummary summary = ObjectSummary.of(object.getLoadKey(), mesh.bounds(), blocks.values(), this::iconOf);
+        return new LoadedObject(blocks, mesh, summary);
+    }
+
+    private static Map<IrisBlockVector, NativeBlockState> visibleBlocks(IrisObject object) {
+        Map<IrisBlockVector, NativeBlockState> blocks = new HashMap<>();
+        object.getBlocks().forEach((position, block) -> {
+            if (!block.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(BlockNames.typeOf(block)));
+            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.replaceScene(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;
+        bakeTimer.discardPending();
+        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 = MapHost.findEngine(worldId);
+        return current != null && !current.isClosed() ? current : startEngine;
+    }
+
+    private BlockModel modelOf(NativeBlockState block) {
+        return models.computeIfAbsent(block.key(), 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(NativeBlockState 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<IrisBlockVector, NativeBlockState> blocks, ObjectMesh mesh, ObjectSummary summary) {
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/ObjectLayerCut.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 art.arcane.iris.studio.map;
+
+import javax.swing.JComponent;
+import java.util.function.IntConsumer;
+
+/**
+ * A 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 {
+    private static final String TOOLTIP = "Hide the top layers to look inside · Page Up / Page Down";
+
+    private final FloatingSlider slider = new FloatingSlider(TOOLTIP, this::showCut);
+    private final IntConsumer onLayersChanged;
+
+    /**
+     * @param onLayersChanged told how many layers from the bottom stay visible whenever the user moves the slider
+     */
+    ObjectLayerCut(IntConsumer onLayersChanged) {
+        this.onLayersChanged = onLayersChanged;
+        showHeight(1);
+    }
+
+    /**
+     * The view with this slider floating over its right edge, halfway down.
+     */
+    JComponent floatingOver(JComponent view) {
+        return slider.floatingOver(view);
+    }
+
+    /**
+     * Shows every layer of a newly chosen object without telling anyone, since nothing is hidden yet.
+     */
+    void showHeight(int layers) {
+        int layerCount = Math.max(1, layers);
+        slider.showQuietly(1, layerCount, layerCount);
+        showCutState();
+        slider.setVisible(layers > 1);
+    }
+
+    void stepBy(int layers) {
+        if (slider.isVisible()) {
+            slider.moveBy(layers);
+        }
+    }
+
+    boolean isCutting() {
+        return slider.value() < slider.maximum();
+    }
+
+    int shownLayerCount() {
+        return slider.value();
+    }
+
+    int layerCount() {
+        return slider.maximum();
+    }
+
+    private void showCut(int shownLayers) {
+        showCutState();
+        onLayersChanged.accept(shownLayers);
+    }
+
+    private void showCutState() {
+        slider.showLabel(isCutting() ? Integer.toString(slider.value()) : "");
+        slider.setStandingOut(isCutting());
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/ObjectMesh.java

@@ -0,0 +1,289 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.generation.decoration.IrisProceduralBlocks;
+import art.arcane.iris.generation.geometry.IrisBlockVector;
+import art.arcane.iris.studio.map.BlockModel.Face;
+import art.arcane.volmlib.nativelib.terrain.NativeBlockState;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+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) implements OrbitScene {
+    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<IrisBlockVector, NativeBlockState> blocks, Function<NativeBlockState, 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<IrisBlockVector, NativeBlockState> blocks, Function<NativeBlockState, BlockModel> modelOf, Bounds bounds,
+                            Predicate<NativeBlockState> 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 (IrisBlockVector 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));
+        }
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return solidQuads.isEmpty() && translucentQuads.isEmpty() && cutAwayQuads.isEmpty();
+    }
+
+    @Override
+    public OrbitPicture render(OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        return renderOnCard(camera, width, height, coveredLeftWidth)
+                .orElseGet(() -> ObjectRenderer.render(this, camera, width, height, coveredLeftWidth));
+    }
+
+    private Optional<OrbitPicture> renderOnCard(OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        if (!GpuLibrary.isLoaded()) {
+            return Optional.empty();
+        }
+        return GpuObjectRenderer.render(this, camera, width, height, coveredLeftWidth);
+    }
+
+    @Override
+    public boolean canRenderOnScreen() {
+        return GpuLibrary.isLoaded() && GpuFrames.canDrawOnScreen();
+    }
+
+    @Override
+    public Optional<OrbitPicture> renderOnScreen(ScreenTarget screen, OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        return GpuObjectRenderer.renderOnScreen(this, screen, camera, width, height, coveredLeftWidth);
+    }
+
+    @Override
+    public OrbitProjection projection(OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        return ObjectRenderer.projection(this, camera, width, height, coveredLeftWidth);
+    }
+
+    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 NativeBlockState[] blocks;
+        private final BlockModel[] models;
+        private final boolean[] seeThrough;
+
+        BlockGrid(Map<IrisBlockVector, NativeBlockState> placed, Function<NativeBlockState, BlockModel> modelOf, Bounds bounds,
+                  Predicate<NativeBlockState> isSeeThrough) {
+            this.bounds = bounds;
+            int cells = bounds.sizeX() * bounds.sizeY() * bounds.sizeZ();
+            this.blocks = new NativeBlockState[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());
+            NativeBlockState 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 isSameBlockType(neighbour, blocks[cell]) && models[cell].hidesSameBlockSides()
+                    && neighbourModel.hidesSameBlockSides();
+        }
+
+        private static boolean isSameBlockType(NativeBlockState first, NativeBlockState second) {
+            return IrisProceduralBlocks.materialKey(first).equals(IrisProceduralBlocks.materialKey(second));
+        }
+
+        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, and the height the
+     * terrain surface meets the object at.
+     */
+    record Bounds(int minX, int minY, int minZ, int maxX, int maxY, int maxZ, int groundY) {
+        private static final Bounds EMPTY = new Bounds(0, 0, 0, 1, 1, 1);
+
+        /** An extent standing on its lowest block. */
+        Bounds(int minX, int minY, int minZ, int maxX, int maxY, int maxZ) {
+            this(minX, minY, minZ, maxX, maxY, maxZ, minY);
+        }
+
+        /** This extent with the terrain surface at {@code groundY}, so anything below it shows as buried. */
+        Bounds standingOn(int groundY) {
+            return new Bounds(minX, minY, minZ, maxX, maxY, maxZ, groundY);
+        }
+
+        static Bounds of(Iterable<IrisBlockVector> 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 (IrisBlockVector 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/art/arcane/iris/studio/map/ObjectOverviewPanel.java

@@ -0,0 +1,368 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import javax.swing.BorderFactory;
+import javax.swing.BoxLayout;
+import javax.swing.JButton;
+import javax.swing.JComponent;
+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 BakeMeter bakeMeter = new BakeMeter();
+    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
+     * @param showsBakeTime       whether the objects are baked, so the time their bake takes is shown
+     */
+    ObjectOverviewPanel(Consumer<Set<String>> onSeeThroughChanged, boolean showsBakeTime) {
+        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(showsBakeTime), 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 showTimingBake() {
+        bakeMeter.showTiming();
+    }
+
+    void showBakeTiming(BakeTiming timing) {
+        bakeMeter.show(timing);
+    }
+
+    void clear() {
+        summary = null;
+        title.setText(" ");
+        path.setText(" ");
+        for (JLabel value : List.of(size, blockCount, blockTypes, filled)) {
+            value.setText("—");
+        }
+        bakeMeter.clear();
+        rows.clear();
+        seeThroughTypes.clear();
+        showSeeThroughState();
+    }
+
+    private JPanel buildHeader(boolean showsBakeTime) {
+        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));
+        if (showsBakeTime) {
+            JPanel bakeTime = stat("Bake time", bakeMeter);
+            bakeTime.setBorder(StudioTheme.emptyBorder(4, 0, 4, 0));
+            header.add(leftAligned(bakeTime));
+        }
+        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, JComponent 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/art/arcane/iris/studio/map/ObjectRenderer.java

@@ -0,0 +1,305 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.studio.map.BlockModel.Face;
+import art.arcane.iris.studio.map.BlockModel.TextureMapping;
+import art.arcane.iris.studio.map.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 OrbitCamera THUMBNAIL_CAMERA = new OrbitCamera(OrbitCamera.START.yaw(), OrbitCamera.START.pitch(), 1.9D, Vec3.ZERO);
+
+    private final int width;
+    private final int height;
+    private final int[] pixels;
+    private final double[] depths;
+    private final boolean[] showsObject;
+    private final OrbitProjection projection;
+    private final int gridColor = GRID.getRGB() & 0xFFFFFF;
+
+    private ObjectRenderer(BufferedImage image, OrbitProjection 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);
+    }
+
+    static OrbitPicture render(ObjectMesh mesh, OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        BufferedImage image = blankImage(width, height);
+        ObjectRenderer renderer = new ObjectRenderer(image, projection(mesh, camera, image.getWidth(), image.getHeight(), coveredLeftWidth));
+        renderer.drawGrid(mesh.bounds());
+        renderer.drawMesh(mesh);
+        return OrbitPicture.of(image, renderer.depths, renderer.projection);
+    }
+
+    static OrbitProjection projection(ObjectMesh mesh, OrbitCamera camera, int width, int height, int coveredLeftWidth) {
+        int covered = Math.max(0, Math.min(Math.max(1, width) - 1, coveredLeftWidth));
+        return projection(mesh.bounds(), mesh.bounds(), camera, Math.max(1, width), Math.max(1, height), covered);
+    }
+
+    /**
+     * 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, projection(mesh.bounds(), sizeToFit, THUMBNAIL_CAMERA, image.getWidth(), image.getHeight(), 0)).drawMesh(mesh);
+        return image;
+    }
+
+    /**
+     * @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 static OrbitProjection projection(ObjectMesh.Bounds shown, ObjectMesh.Bounds scaledAs, OrbitCamera camera,
+                                              int width, int height, int coveredLeftWidth) {
+        Vec3 center = new Vec3((shown.minX() + shown.maxX()) / 2D, shown.minY() + scaledAs.sizeY() / 2D, (shown.minZ() + shown.maxZ()) / 2D);
+        Vec3 fittedSize = new Vec3(scaledAs.sizeX(), scaledAs.sizeY(), scaledAs.sizeZ());
+        return new OrbitProjection(center, fittedSize, camera, OrbitCamera.START, width, height, coveredLeftWidth);
+    }
+
+    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) {
+        FloorGrid grid = FloorGrid.under(bounds);
+        int reach = grid.reach();
+        for (int offset = -reach; offset <= reach; offset += grid.step()) {
+            drawLine(grid.centerX() + offset, grid.floorY(), grid.centerZ() - reach, grid.centerX() + offset, grid.floorY(), grid.centerZ() + reach);
+            drawLine(grid.centerX() - reach, grid.floorY(), grid.centerZ() + offset, grid.centerX() + reach, grid.floorY(), grid.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.
+     */
+    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));
+        }
+    }
+
+    /**
+     * The grid on the ground under an object, a square of lines reaching past it on every side.
+     */
+    record FloorGrid(int centerX, double floorY, int centerZ, int reach, int step) {
+        static FloorGrid under(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));
+            return new FloorGrid(Math.floorDiv(bounds.minX() + bounds.maxX(), 2), bounds.groundY() - GRID_BELOW_OBJECT,
+                    Math.floorDiv(bounds.minZ() + bounds.maxZ(), 2), reach, step);
+        }
+
+        int linesPerDirection() {
+            return 2 * reach / step + 1;
+        }
+
+        int color() {
+            return GRID.getRGB();
+        }
+    }
+
+    private enum Pass {
+        SOLID,
+        CUT_AWAY_GHOST,
+        BLENDED
+    }
+}

core/src/main/java/art/arcane/iris/studio/map/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 art.arcane.iris.studio.map;
+
+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/art/arcane/iris/studio/map/ObjectSource.java

@@ -0,0 +1,71 @@
+/*
+ * 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 art.arcane.iris.studio.map;
+
+import art.arcane.iris.pack.loading.IrisData;
+import art.arcane.iris.structure.object.IrisObject;
+
+import java.util.List;
+import java.util.OptionalInt;
+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 height, in {@code object}'s own blocks, that the terrain surface meets; empty to stand it on its lowest block. */
+    default OptionalInt groundY(IrisObject object) {
+        return OptionalInt.empty();
+    }
+
+    /** 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");
+    }
+
+    /** Whether its entries are baked from settings, which costs world generation time worth measuring. */
+    default boolean isBaked() {
+        return false;
+    }
+
+    /**
+     * Bakes the entry's variants from {@code seed} once more and times it; null when the entry is gone. Only asked of
+     * baked sources, on a thread of its own.
+     */
+    default BakeRun timeBake(IrisData data, String key, long seed) {
+        throw new UnsupportedOperationException(key + " is not baked");
+    }
+}