Fix Iris entity spawn delegation

adapters/bukkit/nms/v26_2_R1/src/main/java/art/arcane/iris/core/nms/v26_2_R1/IrisChunkGenerator.java

@@ -37,6 +37,7 @@ import net.minecraft.util.random.WeightedList;
 import net.minecraft.world.level.ChunkPos;
 import net.minecraft.world.level.Level;
 import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.NaturalSpawner;
 import net.minecraft.world.level.NoiseColumn;
 import net.minecraft.world.level.StructureManager;
 import net.minecraft.world.level.WorldGenLevel;
@@ -46,6 +47,7 @@ import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
 import net.minecraft.world.level.levelgen.GenerationStep;
 import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.LegacyRandomSource;
 import net.minecraft.world.level.levelgen.RandomState;
 import net.minecraft.world.level.levelgen.RandomSupport;
 import net.minecraft.world.level.levelgen.WorldgenRandom;
@@ -574,8 +576,14 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     }
 
     @Override
-    public void spawnOriginalMobs(WorldGenRegion regionlimitedworldaccess) {
+    public void spawnOriginalMobs(WorldGenRegion region) {
-        delegate.spawnOriginalMobs(regionlimitedworldaccess);
+        ChunkPos center = region.getCenter();
+        Holder<Biome> visibleBiome = region.getBiome(center.getWorldPosition().atY(region.getMaxY()));
+        Holder<Biome> vanillaBiome = customBiomeSource.getVanillaSpawnBiome(visibleBiome);
+        WorldgenRandom random = new WorldgenRandom(new LegacyRandomSource(RandomSupport.generateUniqueSeed()));
+        random.setDecorationSeed(region.getSeed(), center.getMinBlockX(), center.getMinBlockZ());
+        NaturalSpawner.spawnMobsForChunkGeneration(
+                region, vanillaBiome == null ? visibleBiome : vanillaBiome, center, random);
     }
 
     private static WeightedList<MobSpawnSettings.SpawnerData> mergeSpawnTables(

adapters/bukkit/nms/v26_2_R1/src/test/java/art/arcane/iris/core/nms/v26_2_R1/IrisChunkGeneratorFailureContractTest.java

@@ -64,4 +64,19 @@ public class IrisChunkGeneratorFailureContractTest {
         assertTrue(source.contains("engine.acquireGenerationLease(\"bukkit_nms_base_column\")"));
         assertTrue(source.contains("catch (GenerationSessionException e)"));
     }
+
+    @Test
+    public void vanillaChunkGenerationMobsUseTheVisibleBiomesVanillaDerivative() throws IOException {
+        String source = Files.readString(Path.of(System.getProperty("iris.nmsChunkGeneratorSource")));
+        int spawnStart = source.indexOf("public void spawnOriginalMobs");
+        int spawnEnd = source.indexOf("private static WeightedList", spawnStart);
+        String spawn = source.substring(spawnStart, spawnEnd);
+
+        assertTrue(spawn.contains("customBiomeSource.getVanillaSpawnBiome(visibleBiome)"));
+        assertTrue(spawn.contains("NaturalSpawner.spawnMobsForChunkGeneration("));
+        assertTrue(spawn.contains("region.getBiome(center.getWorldPosition().atY(region.getMaxY()))"));
+        assertTrue(spawn.contains("new LegacyRandomSource(RandomSupport.generateUniqueSeed())"));
+        assertTrue(spawn.contains("random.setDecorationSeed(region.getSeed()"));
+        assertFalse(spawn.contains("delegate.spawnOriginalMobs"));
+    }
 }

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

@@ -971,7 +971,7 @@ public class Iris extends VolmitPlugin implements Listener, ReloadAware {
                         final Location spawn = w.getSpawnLocation();
                         for (Player i : getServer().getOnlinePlayers()) {
                             final Runnable playerTask = () -> {
-                                i.setGameMode(GameMode.SPECTATOR);
+                                i.setGameMode(GameMode.CREATIVE);
                                 BukkitPlatform.teleportAsync(i, spawn);
                             };
                             if (!J.runEntity(i, playerTask)) {

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

@@ -657,7 +657,7 @@ public class CommandStudio implements DirectorExecutor {
                 .getTarget()
                 .getWorld();
         BukkitPlatform.teleportAsync(player, BukkitWorldBinding.spawnLocation(studioWorld))
-                .thenRun(() -> player.setGameMode(GameMode.SPECTATOR));
+                .thenRun(() -> player.setGameMode(GameMode.CREATIVE));
     }
 
     @Director(description = "Update your dimension projects VSCode workspace", descriptionKey = "iris.director.commandstudio.director.update_your_dimension_projects_vscode_workspace")

adapters/bukkit/plugin/src/test/java/art/arcane/iris/core/runtime/StudioPlayerModeContractTest.java

@@ -0,0 +1,24 @@
+package art.arcane.iris.core.runtime;
+
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class StudioPlayerModeContractTest {
+    @Test
+    public void studioEntryKeepsPlayersEligibleForNaturalSpawning() throws IOException {
+        String plugin = Files.readString(Path.of("src/main/java/art/arcane/iris/Iris.java"));
+        String commands = Files.readString(Path.of(
+                "src/main/java/art/arcane/iris/core/commands/CommandStudio.java"));
+
+        assertFalse(plugin.contains("GameMode.SPECTATOR"));
+        assertFalse(commands.contains("GameMode.SPECTATOR"));
+        assertTrue(plugin.contains("GameMode.CREATIVE"));
+        assertTrue(commands.contains("GameMode.CREATIVE"));
+    }
+}

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

@@ -63,6 +63,7 @@ import net.minecraft.world.entity.MobCategory;
 import net.minecraft.world.level.ChunkPos;
 import net.minecraft.world.level.Level;
 import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.NaturalSpawner;
 import net.minecraft.world.level.NoiseColumn;
 import net.minecraft.world.level.StructureManager;
 import net.minecraft.world.level.WorldGenLevel;
@@ -81,6 +82,7 @@ import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
 import net.minecraft.world.level.chunk.LevelChunkSection;
 import net.minecraft.world.level.levelgen.GenerationStep;
 import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.LegacyRandomSource;
 import net.minecraft.world.level.levelgen.RandomState;
 import net.minecraft.world.level.levelgen.RandomSupport;
 import net.minecraft.world.level.levelgen.WorldgenRandom;
@@ -1191,6 +1193,15 @@ public final class IrisModdedChunkGenerator extends ChunkGenerator {
 
     @Override
     public void spawnOriginalMobs(WorldGenRegion region) {
+        Registry<Biome> registry = region.registryAccess().lookupOrThrow(Registries.BIOME);
+        initializeVanillaSpawnBiomes(registry);
+        ChunkPos center = region.getCenter();
+        Holder<Biome> visibleBiome = region.getBiome(center.getWorldPosition().atY(region.getMaxY()));
+        Holder<Biome> vanillaBiome = vanillaSpawnBiomes.get(visibleBiome.value());
+        WorldgenRandom random = new WorldgenRandom(new LegacyRandomSource(RandomSupport.generateUniqueSeed()));
+        random.setDecorationSeed(region.getSeed(), center.getMinBlockX(), center.getMinBlockZ());
+        NaturalSpawner.spawnMobsForChunkGeneration(
+                region, vanillaBiome == null ? visibleBiome : vanillaBiome, center, random);
     }
 
     @Override

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

@@ -712,7 +712,7 @@ public final class ModdedWorldManager implements EngineWorldManager {
     }
 
     private boolean isEntitySpawningEnabledForCurrentWorld() {
-        return entitySpawningEnabled(engine.isStudio(), IrisSettings.get().getStudio().isEnableEntitySpawning());
+        return entitySpawningEnabled(engine.isStudio(), IrisSettings.get().getStudio().isEntitySpawning());
     }
 
     static boolean entitySpawningEnabled(boolean studio, boolean studioSetting) {

adapters/modded-common/src/test/java/art/arcane/iris/modded/IrisModdedChunkGeneratorSpawnTest.java

@@ -9,9 +9,13 @@ import net.minecraft.world.level.biome.MobSpawnSettings;
 import org.junit.Test;
 import org.junit.BeforeClass;
 
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.List;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 public class IrisModdedChunkGeneratorSpawnTest {
     @BeforeClass
@@ -44,4 +48,20 @@ public class IrisModdedChunkGeneratorSpawnTest {
         assertEquals(explicitCow, entries.get(2).value());
         assertEquals(3, entries.get(2).weight());
     }
+
+    @Test
+    public void vanillaChunkGenerationMobsUseTheVisibleBiomesVanillaDerivative() throws IOException {
+        Path sourcePath = Path.of(System.getProperty("iris.moddedCommonSources"),
+                "art/arcane/iris/modded/IrisModdedChunkGenerator.java");
+        String source = Files.readString(sourcePath);
+        int spawnStart = source.indexOf("public void spawnOriginalMobs");
+        int spawnEnd = source.indexOf("@Override", spawnStart + 1);
+        String spawn = source.substring(spawnStart, spawnEnd);
+
+        assertTrue(spawn.contains("initializeVanillaSpawnBiomes(registry)"));
+        assertTrue(spawn.contains("vanillaSpawnBiomes.get(visibleBiome.value())"));
+        assertTrue(spawn.contains("NaturalSpawner.spawnMobsForChunkGeneration("));
+        assertTrue(spawn.contains("new LegacyRandomSource(RandomSupport.generateUniqueSeed())"));
+        assertTrue(spawn.contains("random.setDecorationSeed(region.getSeed()"));
+    }
 }

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

@@ -295,7 +295,7 @@ public class IrisSettings {
         public boolean studio = true;
         public boolean openVSCode = true;
         public boolean disableTimeAndWeather = true;
-        public boolean enableEntitySpawning = false;
+        public boolean entitySpawning = true;
         public boolean autoStartDefaultStudio = false;
     }
 

core/src/main/java/art/arcane/iris/core/project/IrisProject.java

@@ -295,7 +295,7 @@ public class IrisProject {
                 }
 
                 if (sender.isPlayer() && sender.player() != null) {
-                    J.runEntity(sender.player(), () -> sender.player().setGameMode(GameMode.SPECTATOR));
+                    J.runEntity(sender.player(), () -> sender.player().setGameMode(GameMode.CREATIVE));
                 }
                 activeProvider = IrisToolbelt.access(result.world());
                 maintenanceWorld = result.world();

core/src/main/java/art/arcane/iris/core/runtime/WorldRuntimeControlService.java

@@ -82,6 +82,7 @@ public final class WorldRuntimeControlService {
 
         IrisServices.get(art.arcane.iris.core.link.MultiverseCoreLink.class).removeFromConfig(world);
         setIntGameRule(world, 0, "SPAWN_CHUNK_RADIUS", "spawnChunkRadius");
+        enableStudioEntitySpawning(world);
         if (!IrisSettings.get().getStudio().isDisableTimeAndWeather()) {
             return true;
         }
@@ -100,17 +101,12 @@ public final class WorldRuntimeControlService {
         applyStudioWorldRules(world);
 
         setBooleanGameRule(world, false, "DO_FIRE_TICK", "doFireTick");
-        setBooleanGameRule(world, false, "DO_MOB_SPAWNING", "doMobSpawning");
         setBooleanGameRule(world, false, "DO_MOB_LOOT", "doMobLoot");
-        setBooleanGameRule(world, false, "DO_TRADER_SPAWNING", "doTraderSpawning");
-        setBooleanGameRule(world, false, "DO_PATROL_SPAWNING", "doPatrolSpawning");
-        setBooleanGameRule(world, false, "DO_INSOMNIA", "doInsomnia");
         setBooleanGameRule(world, true, "DO_IMMEDIATE_RESPAWN", "doImmediateRespawn");
         setBooleanGameRule(world, false, "FALL_DAMAGE", "fallDamage");
         setBooleanGameRule(world, false, "FIRE_DAMAGE", "fireDamage");
         setBooleanGameRule(world, false, "DROWNING_DAMAGE", "drowningDamage");
         setBooleanGameRule(world, false, "FREEZE_DAMAGE", "freezeDamage");
-        setBooleanGameRule(world, false, "DO_WARDEN_SPAWNING", "doWardenSpawning");
         setBooleanGameRule(world, false, "MOB_GRIEFING", "mobGriefing");
         setBooleanGameRule(world, false, "DO_TILE_DROPS", "doTileDrops");
         setBooleanGameRule(world, true, "KEEP_INVENTORY", "keepInventory");
@@ -121,6 +117,14 @@ public final class WorldRuntimeControlService {
         return true;
     }
 
+    static void enableStudioEntitySpawning(World world) {
+        setBooleanGameRule(world, true, "DO_MOB_SPAWNING", "doMobSpawning");
+        setBooleanGameRule(world, true, "DO_TRADER_SPAWNING", "doTraderSpawning");
+        setBooleanGameRule(world, true, "DO_PATROL_SPAWNING", "doPatrolSpawning");
+        setBooleanGameRule(world, true, "DO_INSOMNIA", "doInsomnia");
+        setBooleanGameRule(world, true, "DO_WARDEN_SPAWNING", "doWardenSpawning");
+    }
+
     public boolean applyNoonTimeLock(World world) {
         if (world == null) {
             return false;

core/src/main/java/art/arcane/iris/core/service/ObjectStudioSaveService.java

@@ -40,8 +40,6 @@ import org.bukkit.block.Block;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.block.Action;
-import org.bukkit.event.entity.CreatureSpawnEvent;
-import org.bukkit.event.entity.EntitySpawnEvent;
 import org.bukkit.event.player.PlayerInteractEvent;
 import org.bukkit.event.world.WorldUnloadEvent;
 import org.bukkit.inventory.EquipmentSlot;
@@ -129,26 +127,6 @@ public class ObjectStudioSaveService implements IrisService {
         unregister(event.getWorld());
     }
 
-    @EventHandler(ignoreCancelled = true)
-    public void onCreatureSpawn(CreatureSpawnEvent event) {
-        if (!studios.containsKey(event.getLocation().getWorld().getUID())) return;
-        CreatureSpawnEvent.SpawnReason reason = event.getSpawnReason();
-        if (reason == CreatureSpawnEvent.SpawnReason.CUSTOM
-                || reason == CreatureSpawnEvent.SpawnReason.COMMAND
-                || reason == CreatureSpawnEvent.SpawnReason.SPAWNER_EGG) {
-            return;
-        }
-        event.setCancelled(true);
-    }
-
-    @EventHandler(ignoreCancelled = true)
-    public void onEntitySpawn(EntitySpawnEvent event) {
-        if (event instanceof CreatureSpawnEvent) return;
-        if (!studios.containsKey(event.getLocation().getWorld().getUID())) return;
-        if (event.getEntity() instanceof org.bukkit.entity.Player) return;
-        event.setCancelled(true);
-    }
-
     @EventHandler(ignoreCancelled = true)
     public void onPlayerInteract(PlayerInteractEvent event) {
         if (event.getHand() != EquipmentSlot.HAND) return;

core/src/main/java/art/arcane/iris/engine/IrisWorldManager.java

@@ -979,7 +979,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
             return true;
         }
 
-        return IrisSettings.get().getStudio().isEnableEntitySpawning();
+        return IrisSettings.get().getStudio().isEntitySpawning();
     }
 
     private KList<IrisEntitySpawn> spawnRandomly(List<IrisEntitySpawn> types) {

core/src/test/java/art/arcane/iris/core/runtime/StudioEntitySpawningTest.java

@@ -0,0 +1,55 @@
+package art.arcane.iris.core.runtime;
+
+import art.arcane.iris.core.IrisSettings;
+import art.arcane.iris.core.service.ObjectStudioSaveService;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class StudioEntitySpawningTest {
+    @Test
+    public void studioEntitySpawningDefaultsToEnabled() {
+        assertTrue(new IrisSettings.IrisSettingsStudio().isEntitySpawning());
+    }
+
+    @Test
+    public void studioWorldRulesEnableVanillaMobSpawning() throws IOException {
+        String source = Files.readString(Path.of(
+                "src/main/java/art/arcane/iris/core/runtime/WorldRuntimeControlService.java"));
+        int helperStart = source.indexOf("static void enableStudioEntitySpawning");
+        int helperEnd = source.indexOf("public boolean applyNoonTimeLock", helperStart);
+        String helper = source.substring(helperStart, helperEnd);
+
+        assertTrue(source.contains("enableStudioEntitySpawning(world);"));
+        assertTrue(helper.contains("setBooleanGameRule(world, true, \"DO_MOB_SPAWNING\""));
+        assertTrue(helper.contains("setBooleanGameRule(world, true, \"DO_TRADER_SPAWNING\""));
+        assertTrue(helper.contains("setBooleanGameRule(world, true, \"DO_PATROL_SPAWNING\""));
+        assertTrue(helper.contains("setBooleanGameRule(world, true, \"DO_INSOMNIA\""));
+        assertTrue(helper.contains("setBooleanGameRule(world, true, \"DO_WARDEN_SPAWNING\""));
+        assertFalse(helper.contains("setBooleanGameRule(world, false, \"DO_MOB_SPAWNING\""));
+    }
+
+    @Test
+    public void generalStudioUsesAPlayerModeEligibleForNaturalSpawning() throws IOException {
+        String source = Files.readString(Path.of(
+                "src/main/java/art/arcane/iris/core/project/IrisProject.java"));
+
+        assertFalse(source.contains("GameMode.SPECTATOR"));
+        assertTrue(source.contains("GameMode.CREATIVE"));
+    }
+
+    @Test
+    public void objectStudioDoesNotCancelEntitySpawns() {
+        boolean hasSpawnCanceller = Arrays.stream(ObjectStudioSaveService.class.getDeclaredMethods())
+                .anyMatch(method -> method.getName().equals("onCreatureSpawn")
+                        || method.getName().equals("onEntitySpawn"));
+
+        assertFalse(hasSpawnCanceller);
+    }
+}