x

nms/v1_21_R7/src/main/java/art/arcane/iris/core/nms/v1_21_R7/CustomBiomeSource.java

@@ -42,6 +42,7 @@ public class CustomBiomeSource extends BiomeSource {
     private final KMap<String, Holder<Biome>> customBiomes;
     private final Holder<Biome> fallbackBiome;
     private final ConcurrentHashMap<Long, Holder<Biome>> noiseBiomeCache = new ConcurrentHashMap<>();
+    private final ConcurrentHashMap<Long, Holder<Biome>> structureBiomeCache = new ConcurrentHashMap<>();
 
     public CustomBiomeSource(long seed, Engine engine, World world) {
         this.engine = engine;
@@ -173,13 +174,33 @@ public class CustomBiomeSource extends BiomeSource {
 
     @Override
     public Holder<Biome> getNoiseBiome(int x, int y, int z, Climate.Sampler sampler) {
+        long cacheKey = packNoiseKey(x, y, z);
+        Holder<Biome> cachedHolder = structureBiomeCache.get(cacheKey);
+        if (cachedHolder != null) {
+            return cachedHolder;
+        }
+
+        Holder<Biome> resolvedHolder = resolveStructureBiomeHolder(x, y, z);
+        Holder<Biome> existingHolder = structureBiomeCache.putIfAbsent(cacheKey, resolvedHolder);
+        if (existingHolder != null) {
+            return existingHolder;
+        }
+
+        if (structureBiomeCache.size() > NOISE_BIOME_CACHE_MAX) {
+            structureBiomeCache.clear();
+        }
+
+        return resolvedHolder;
+    }
+
+    public Holder<Biome> getVisibleNoiseBiome(int x, int y, int z, Climate.Sampler sampler) {
         long cacheKey = packNoiseKey(x, y, z);
         Holder<Biome> cachedHolder = noiseBiomeCache.get(cacheKey);
         if (cachedHolder != null) {
             return cachedHolder;
         }
 
-        Holder<Biome> resolvedHolder = resolveNoiseBiomeHolder(x, y, z);
+        Holder<Biome> resolvedHolder = resolveVisibleBiomeHolder(x, y, z);
         Holder<Biome> existingHolder = noiseBiomeCache.putIfAbsent(cacheKey, resolvedHolder);
         if (existingHolder != null) {
             return existingHolder;
@@ -192,15 +213,66 @@ public class CustomBiomeSource extends BiomeSource {
         return resolvedHolder;
     }
 
-    private Holder<Biome> resolveNoiseBiomeHolder(int x, int y, int z) {
-        if (engine == null || engine.isClosed()) {
+    private Holder<Biome> resolveStructureBiomeHolder(int x, int y, int z) {
+        BiomeResolution resolution = resolveBiomeResolution(x, y, z);
+        if (resolution == null) {
             return getFallbackBiome();
         }
 
-        if (engine.getComplex() == null) {
+        if (resolution.irisBiome.isCustom()) {
+            return resolveCustomHolder(resolution);
+        }
+
+        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, resolution.irisBiome.getVanillaDerivative());
+        if (holder != null) {
+            return holder;
+        }
+
+        return getFallbackBiome();
+    }
+
+    private Holder<Biome> resolveVisibleBiomeHolder(int x, int y, int z) {
+        BiomeResolution resolution = resolveBiomeResolution(x, y, z);
+        if (resolution == null) {
             return getFallbackBiome();
         }
 
+        if (resolution.irisBiome.isCustom()) {
+            return resolveCustomHolder(resolution);
+        }
+
+        org.bukkit.block.Biome vanillaBiome = resolution.underground
+                ? resolution.irisBiome.getGroundBiome(resolution.rng, resolution.blockX, resolution.blockY, resolution.blockZ)
+                : resolution.irisBiome.getSkyBiome(resolution.rng, resolution.blockX, resolution.blockY, resolution.blockZ);
+        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, vanillaBiome);
+        if (holder != null) {
+            return holder;
+        }
+
+        return getFallbackBiome();
+    }
+
+    private Holder<Biome> resolveCustomHolder(BiomeResolution resolution) {
+        IrisBiomeCustom customBiome = resolution.irisBiome.getCustomBiome(resolution.rng, resolution.blockX, resolution.blockY, resolution.blockZ);
+        if (customBiome != null) {
+            Holder<Biome> holder = customBiomes.get(customBiome.getId());
+            if (holder != null) {
+                return holder;
+            }
+        }
+
+        return getFallbackBiome();
+    }
+
+    private BiomeResolution resolveBiomeResolution(int x, int y, int z) {
+        if (engine == null || engine.isClosed()) {
+            return null;
+        }
+
+        if (engine.getComplex() == null) {
+            return null;
+        }
+
         int blockX = x << 2;
         int blockZ = z << 2;
         int blockY = y << 2;
@@ -218,7 +290,7 @@ public class CustomBiomeSource extends BiomeSource {
             irisBiome = engine.getComplex().getTrueBiomeStream().get(blockX, blockZ);
         }
         if (irisBiome == null) {
-            return getFallbackBiome();
+            return null;
         }
 
         RNG noiseRng = new RNG(seed
@@ -226,27 +298,7 @@ public class CustomBiomeSource extends BiomeSource {
                 ^ (((long) blockY) * 132897987541L)
                 ^ (((long) blockZ) * 42317861L));
 
-        if (irisBiome.isCustom()) {
-            IrisBiomeCustom customBiome = irisBiome.getCustomBiome(noiseRng, blockX, blockY, blockZ);
-            if (customBiome != null) {
-                Holder<Biome> holder = customBiomes.get(customBiome.getId());
-                if (holder != null) {
-                    return holder;
-                }
-            }
-
-            return getFallbackBiome();
-        }
-
-        org.bukkit.block.Biome vanillaBiome = underground
-                ? irisBiome.getGroundBiome(noiseRng, blockX, blockY, blockZ)
-                : irisBiome.getSkyBiome(noiseRng, blockX, blockY, blockZ);
-        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, vanillaBiome);
-        if (holder != null) {
-            return holder;
-        }
-
-        return getFallbackBiome();
+        return new BiomeResolution(irisBiome, underground, blockX, blockY, blockZ, noiseRng);
     }
 
     private Holder<Biome> getFallbackBiome() {
@@ -328,4 +380,22 @@ public class CustomBiomeSource extends BiomeSource {
 
         return null;
     }
+
+    private static final class BiomeResolution {
+        private final IrisBiome irisBiome;
+        private final boolean underground;
+        private final int blockX;
+        private final int blockY;
+        private final int blockZ;
+        private final RNG rng;
+
+        private BiomeResolution(IrisBiome irisBiome, boolean underground, int blockX, int blockY, int blockZ, RNG rng) {
+            this.irisBiome = irisBiome;
+            this.underground = underground;
+            this.blockX = blockX;
+            this.blockY = blockY;
+            this.blockZ = blockZ;
+            this.rng = rng;
+        }
+    }
 }

nms/v1_21_R7/src/main/java/art/arcane/iris/core/nms/v1_21_R7/IrisChunkGenerator.java

@@ -50,11 +50,18 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
+    private final CustomBiomeSource customBiomeSource;
+    private volatile Set<String> reachableStructureKeysCache;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
-        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
+        this(delegate, engine, world, new CustomBiomeSource(seed, engine, world));
+    }
+
+    private IrisChunkGenerator(ChunkGenerator delegate, Engine engine, World world, CustomBiomeSource customBiomeSource) {
+        super(((CraftWorld) world).getHandle(), edit(delegate, customBiomeSource), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.customBiomeSource = customBiomeSource;
     }
 
     @Override
@@ -91,13 +98,40 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         if (!importedControl().active()) {
             return null;
         }
+        HolderSet<Structure> reachable = filterReachableStructures(level, holders);
+        if (reachable == null || reachable.size() == 0) {
+            return null;
+        }
         try {
-            return delegate.findNearestMapStructure(level, holders, pos, radius, findUnexplored);
+            return delegate.findNearestMapStructure(level, reachable, pos, radius, findUnexplored);
         } catch (Throwable e) {
             return null;
         }
     }
 
+    private HolderSet<Structure> filterReachableStructures(ServerLevel level, HolderSet<Structure> holders) {
+        Set<String> reachable = reachableStructureKeysCache;
+        if (reachable == null) {
+            reachable = VanillaStructureBiomes.reachableStructureKeys(level, delegate.getBiomeSource());
+            reachableStructureKeysCache = reachable;
+        }
+        if (reachable.isEmpty()) {
+            return holders;
+        }
+        Registry<Structure> registry = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        List<Holder<Structure>> kept = new ArrayList<>();
+        for (Holder<Structure> holder : holders) {
+            Object id = registry.getKey(holder.value());
+            if (id != null && reachable.contains(id.toString())) {
+                kept.add(holder);
+            }
+        }
+        if (kept.size() == holders.size()) {
+            return holders;
+        }
+        return HolderSet.direct(kept);
+    }
+
     @Override
     protected MapCodec<? extends ChunkGenerator> codec() {
         return MapCodec.unit(null);
@@ -144,7 +178,8 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public CompletableFuture<ChunkAccess> createBiomes(RandomState randomstate, Blender blender, StructureManager structuremanager, ChunkAccess ichunkaccess) {
-        return delegate.createBiomes(randomstate, blender, structuremanager, ichunkaccess);
+        ichunkaccess.fillBiomesFromNoise(customBiomeSource::getVisibleNoiseBiome, randomstate.sampler());
+        return CompletableFuture.completedFuture(ichunkaccess);
     }
 
     @Override

nms/v1_21_R7/src/main/java/art/arcane/iris/core/nms/v1_21_R7/NMSBinding.java

@@ -44,6 +44,7 @@ import net.minecraft.tags.TagKey;
 import net.minecraft.world.attribute.EnvironmentAttributes;
 import net.minecraft.world.entity.EntityType;
 import net.minecraft.world.item.component.CustomData;
+import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.Biomes;
 import net.minecraft.world.level.block.Block;
 import net.minecraft.world.level.block.Blocks;
@@ -89,9 +90,12 @@ import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.*;
 import java.util.List;
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import ca.spottedleaf.moonrise.patches.chunk_system.io.MoonriseRegionFileIO;
 
 public class NMSBinding implements INMSBinding {
     private final KMap<Biome, Object> baseBiomeCache = new KMap<>();
@@ -412,6 +416,43 @@ public class NMSBinding implements INMSBinding {
         return keys;
     }
 
+    @Override
+    public KList<String> getReachableStructureKeys(World world) {
+        KList<String> keys = new KList<>();
+        try {
+            ServerLevel level = ((CraftWorld) world).getHandle();
+            BiomeSource source = level.getChunkSource().getGenerator().getBiomeSource();
+            keys.addAll(VanillaStructureBiomes.reachableStructureKeys(level, source));
+        } catch (Throwable e) {
+            Iris.reportError(e);
+        }
+        return keys;
+    }
+
+    @Override
+    public KList<String> getStructureBiomeKeys(String structureKey) {
+        KList<String> keys = new KList<>();
+        try {
+            keys.addAll(VanillaStructureBiomes.structureBiomeKeys(registry(), structureKey));
+        } catch (Throwable e) {
+            Iris.reportError(e);
+        }
+        return keys;
+    }
+
+    @Override
+    public KList<String> getPossibleBiomeKeys(World world) {
+        KList<String> keys = new KList<>();
+        try {
+            ServerLevel level = ((CraftWorld) world).getHandle();
+            BiomeSource source = level.getChunkSource().getGenerator().getBiomeSource();
+            keys.addAll(VanillaStructureBiomes.possibleBiomeKeys(source));
+        } catch (Throwable e) {
+            Iris.reportError(e);
+        }
+        return keys;
+    }
+
     @Override
     public boolean isBukkit() {
         return true;
@@ -555,6 +596,42 @@ public class NMSBinding implements INMSBinding {
         });
     }
 
+    @Override
+    public boolean purgeChunk(World world, int x, int z) {
+        ServerLevel level = ((CraftWorld) world).getHandle();
+        try {
+            CountDownLatch latch = new CountDownLatch(1);
+            Runnable unload = () -> {
+                try {
+                    if (world.isChunkLoaded(x, z)) {
+                        world.unloadChunk(x, z, false);
+                    }
+                } finally {
+                    latch.countDown();
+                }
+            };
+            if (!J.runRegion(world, x, z, unload)) {
+                return false;
+            }
+            if (!latch.await(15, TimeUnit.SECONDS)) {
+                Iris.warn("Chunk purge timed out waiting to unload " + x + "," + z + " in " + world.getName() + ".");
+                return false;
+            }
+
+            for (MoonriseRegionFileIO.RegionFileType type : MoonriseRegionFileIO.RegionFileType.values()) {
+                MoonriseRegionFileIO.scheduleSave(level, x, z, null, type);
+            }
+            MoonriseRegionFileIO.flush(level);
+            return true;
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            return false;
+        } catch (Throwable e) {
+            Iris.reportError(e);
+            return false;
+        }
+    }
+
     public ItemStack applyCustomNbt(ItemStack itemStack, KMap<String, Object> customNbt) throws IllegalArgumentException {
         if (customNbt != null && !customNbt.isEmpty()) {
             net.minecraft.world.item.ItemStack s = CraftItemStack.asNMSCopy(itemStack);

nms/v1_21_R7/src/main/java/art/arcane/iris/core/nms/v1_21_R7/VanillaStructureBiomes.java

@@ -0,0 +1,77 @@
+package art.arcane.iris.core.nms.v1_21_R7;
+
+import net.minecraft.core.Holder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.BiomeSource;
+import net.minecraft.world.level.levelgen.structure.Structure;
+
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+
+final class VanillaStructureBiomes {
+    private VanillaStructureBiomes() {
+    }
+
+    static Set<String> possibleBiomeKeys(BiomeSource source) {
+        Set<String> keys = new LinkedHashSet<>();
+        if (source == null) {
+            return keys;
+        }
+        for (Holder<Biome> holder : source.possibleBiomes()) {
+            Optional<ResourceKey<Biome>> key = holder.unwrapKey();
+            if (key.isPresent()) {
+                keys.add(key.get().identifier().toString());
+            }
+        }
+        return keys;
+    }
+
+    static Set<String> structureBiomeKeys(RegistryAccess access, String structureKey) {
+        Set<String> keys = new LinkedHashSet<>();
+        if (access == null || structureKey == null || structureKey.isEmpty()) {
+            return keys;
+        }
+        Registry<Structure> registry = access.lookupOrThrow(Registries.STRUCTURE);
+        Structure structure = registry.getValue(Identifier.parse(structureKey));
+        if (structure == null) {
+            return keys;
+        }
+        for (Holder<Biome> holder : structure.biomes()) {
+            Optional<ResourceKey<Biome>> key = holder.unwrapKey();
+            if (key.isPresent()) {
+                keys.add(key.get().identifier().toString());
+            }
+        }
+        return keys;
+    }
+
+    static Set<String> reachableStructureKeys(ServerLevel level, BiomeSource source) {
+        Set<String> reachable = new LinkedHashSet<>();
+        if (level == null || source == null) {
+            return reachable;
+        }
+        Set<String> possible = possibleBiomeKeys(source);
+        if (possible.isEmpty()) {
+            return reachable;
+        }
+        Registry<Structure> registry = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        for (Map.Entry<ResourceKey<Structure>, Structure> entry : registry.entrySet()) {
+            for (Holder<Biome> holder : entry.getValue().biomes()) {
+                Optional<ResourceKey<Biome>> key = holder.unwrapKey();
+                if (key.isPresent() && possible.contains(key.get().identifier().toString())) {
+                    reachable.add(entry.getKey().identifier().toString());
+                    break;
+                }
+            }
+        }
+        return reachable;
+    }
+}

nms/v26_1_R1/src/main/java/art/arcane/iris/core/nms/v26_1_R1/CustomBiomeSource.java

@@ -42,6 +42,7 @@ public class CustomBiomeSource extends BiomeSource {
     private final KMap<String, Holder<Biome>> customBiomes;
     private final Holder<Biome> fallbackBiome;
     private final ConcurrentHashMap<Long, Holder<Biome>> noiseBiomeCache = new ConcurrentHashMap<>();
+    private final ConcurrentHashMap<Long, Holder<Biome>> structureBiomeCache = new ConcurrentHashMap<>();
 
     public CustomBiomeSource(long seed, Engine engine, World world) {
         this.engine = engine;
@@ -173,13 +174,33 @@ public class CustomBiomeSource extends BiomeSource {
 
     @Override
     public Holder<Biome> getNoiseBiome(int x, int y, int z, Climate.Sampler sampler) {
+        long cacheKey = packNoiseKey(x, y, z);
+        Holder<Biome> cachedHolder = structureBiomeCache.get(cacheKey);
+        if (cachedHolder != null) {
+            return cachedHolder;
+        }
+
+        Holder<Biome> resolvedHolder = resolveStructureBiomeHolder(x, y, z);
+        Holder<Biome> existingHolder = structureBiomeCache.putIfAbsent(cacheKey, resolvedHolder);
+        if (existingHolder != null) {
+            return existingHolder;
+        }
+
+        if (structureBiomeCache.size() > NOISE_BIOME_CACHE_MAX) {
+            structureBiomeCache.clear();
+        }
+
+        return resolvedHolder;
+    }
+
+    public Holder<Biome> getVisibleNoiseBiome(int x, int y, int z, Climate.Sampler sampler) {
         long cacheKey = packNoiseKey(x, y, z);
         Holder<Biome> cachedHolder = noiseBiomeCache.get(cacheKey);
         if (cachedHolder != null) {
             return cachedHolder;
         }
 
-        Holder<Biome> resolvedHolder = resolveNoiseBiomeHolder(x, y, z);
+        Holder<Biome> resolvedHolder = resolveVisibleBiomeHolder(x, y, z);
         Holder<Biome> existingHolder = noiseBiomeCache.putIfAbsent(cacheKey, resolvedHolder);
         if (existingHolder != null) {
             return existingHolder;
@@ -192,15 +213,66 @@ public class CustomBiomeSource extends BiomeSource {
         return resolvedHolder;
     }
 
-    private Holder<Biome> resolveNoiseBiomeHolder(int x, int y, int z) {
-        if (engine == null || engine.isClosed()) {
+    private Holder<Biome> resolveStructureBiomeHolder(int x, int y, int z) {
+        BiomeResolution resolution = resolveBiomeResolution(x, y, z);
+        if (resolution == null) {
             return getFallbackBiome();
         }
 
-        if (engine.getComplex() == null) {
+        if (resolution.irisBiome.isCustom()) {
+            return resolveCustomHolder(resolution);
+        }
+
+        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, resolution.irisBiome.getVanillaDerivative());
+        if (holder != null) {
+            return holder;
+        }
+
+        return getFallbackBiome();
+    }
+
+    private Holder<Biome> resolveVisibleBiomeHolder(int x, int y, int z) {
+        BiomeResolution resolution = resolveBiomeResolution(x, y, z);
+        if (resolution == null) {
             return getFallbackBiome();
         }
 
+        if (resolution.irisBiome.isCustom()) {
+            return resolveCustomHolder(resolution);
+        }
+
+        org.bukkit.block.Biome vanillaBiome = resolution.underground
+                ? resolution.irisBiome.getGroundBiome(resolution.rng, resolution.blockX, resolution.blockY, resolution.blockZ)
+                : resolution.irisBiome.getSkyBiome(resolution.rng, resolution.blockX, resolution.blockY, resolution.blockZ);
+        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, vanillaBiome);
+        if (holder != null) {
+            return holder;
+        }
+
+        return getFallbackBiome();
+    }
+
+    private Holder<Biome> resolveCustomHolder(BiomeResolution resolution) {
+        IrisBiomeCustom customBiome = resolution.irisBiome.getCustomBiome(resolution.rng, resolution.blockX, resolution.blockY, resolution.blockZ);
+        if (customBiome != null) {
+            Holder<Biome> holder = customBiomes.get(customBiome.getId());
+            if (holder != null) {
+                return holder;
+            }
+        }
+
+        return getFallbackBiome();
+    }
+
+    private BiomeResolution resolveBiomeResolution(int x, int y, int z) {
+        if (engine == null || engine.isClosed()) {
+            return null;
+        }
+
+        if (engine.getComplex() == null) {
+            return null;
+        }
+
         int blockX = x << 2;
         int blockZ = z << 2;
         int blockY = y << 2;
@@ -218,7 +290,7 @@ public class CustomBiomeSource extends BiomeSource {
             irisBiome = engine.getComplex().getTrueBiomeStream().get(blockX, blockZ);
         }
         if (irisBiome == null) {
-            return getFallbackBiome();
+            return null;
         }
 
         RNG noiseRng = new RNG(seed
@@ -226,27 +298,7 @@ public class CustomBiomeSource extends BiomeSource {
                 ^ (((long) blockY) * 132897987541L)
                 ^ (((long) blockZ) * 42317861L));
 
-        if (irisBiome.isCustom()) {
-            IrisBiomeCustom customBiome = irisBiome.getCustomBiome(noiseRng, blockX, blockY, blockZ);
-            if (customBiome != null) {
-                Holder<Biome> holder = customBiomes.get(customBiome.getId());
-                if (holder != null) {
-                    return holder;
-                }
-            }
-
-            return getFallbackBiome();
-        }
-
-        org.bukkit.block.Biome vanillaBiome = underground
-                ? irisBiome.getGroundBiome(noiseRng, blockX, blockY, blockZ)
-                : irisBiome.getSkyBiome(noiseRng, blockX, blockY, blockZ);
-        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, vanillaBiome);
-        if (holder != null) {
-            return holder;
-        }
-
-        return getFallbackBiome();
+        return new BiomeResolution(irisBiome, underground, blockX, blockY, blockZ, noiseRng);
     }
 
     private Holder<Biome> getFallbackBiome() {
@@ -328,4 +380,22 @@ public class CustomBiomeSource extends BiomeSource {
 
         return null;
     }
+
+    private static final class BiomeResolution {
+        private final IrisBiome irisBiome;
+        private final boolean underground;
+        private final int blockX;
+        private final int blockY;
+        private final int blockZ;
+        private final RNG rng;
+
+        private BiomeResolution(IrisBiome irisBiome, boolean underground, int blockX, int blockY, int blockZ, RNG rng) {
+            this.irisBiome = irisBiome;
+            this.underground = underground;
+            this.blockX = blockX;
+            this.blockY = blockY;
+            this.blockZ = blockZ;
+            this.rng = rng;
+        }
+    }
 }

nms/v26_1_R1/src/main/java/art/arcane/iris/core/nms/v26_1_R1/IrisChunkGenerator.java

@@ -50,11 +50,18 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     private static final WrappedReturningMethod<Heightmap, Object> SET_HEIGHT;
     private final ChunkGenerator delegate;
     private final Engine engine;
+    private final CustomBiomeSource customBiomeSource;
+    private volatile Set<String> reachableStructureKeysCache;
 
     public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
-        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
+        this(delegate, engine, world, new CustomBiomeSource(seed, engine, world));
+    }
+
+    private IrisChunkGenerator(ChunkGenerator delegate, Engine engine, World world, CustomBiomeSource customBiomeSource) {
+        super(((CraftWorld) world).getHandle(), edit(delegate, customBiomeSource), null);
         this.delegate = delegate;
         this.engine = engine;
+        this.customBiomeSource = customBiomeSource;
     }
 
     @Override
@@ -91,13 +98,40 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
         if (!importedControl().active()) {
             return null;
         }
+        HolderSet<Structure> reachable = filterReachableStructures(level, holders);
+        if (reachable == null || reachable.size() == 0) {
+            return null;
+        }
         try {
-            return delegate.findNearestMapStructure(level, holders, pos, radius, findUnexplored);
+            return delegate.findNearestMapStructure(level, reachable, pos, radius, findUnexplored);
         } catch (Throwable e) {
             return null;
         }
     }
 
+    private HolderSet<Structure> filterReachableStructures(ServerLevel level, HolderSet<Structure> holders) {
+        Set<String> reachable = reachableStructureKeysCache;
+        if (reachable == null) {
+            reachable = VanillaStructureBiomes.reachableStructureKeys(level, delegate.getBiomeSource());
+            reachableStructureKeysCache = reachable;
+        }
+        if (reachable.isEmpty()) {
+            return holders;
+        }
+        Registry<Structure> registry = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        List<Holder<Structure>> kept = new ArrayList<>();
+        for (Holder<Structure> holder : holders) {
+            Object id = registry.getKey(holder.value());
+            if (id != null && reachable.contains(id.toString())) {
+                kept.add(holder);
+            }
+        }
+        if (kept.size() == holders.size()) {
+            return holders;
+        }
+        return HolderSet.direct(kept);
+    }
+
     @Override
     protected MapCodec<? extends ChunkGenerator> codec() {
         return MapCodec.unit(null);
@@ -144,7 +178,8 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public CompletableFuture<ChunkAccess> createBiomes(RandomState randomstate, Blender blender, StructureManager structuremanager, ChunkAccess ichunkaccess) {
-        return delegate.createBiomes(randomstate, blender, structuremanager, ichunkaccess);
+        ichunkaccess.fillBiomesFromNoise(customBiomeSource::getVisibleNoiseBiome, randomstate.sampler());
+        return CompletableFuture.completedFuture(ichunkaccess);
     }
 
     @Override

nms/v26_1_R1/src/main/java/art/arcane/iris/core/nms/v26_1_R1/NMSBinding.java

@@ -44,6 +44,7 @@ import net.minecraft.tags.TagKey;
 import net.minecraft.world.attribute.EnvironmentAttributes;
 import net.minecraft.world.entity.EntityType;
 import net.minecraft.world.item.component.CustomData;
+import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.Biomes;
 import net.minecraft.world.level.block.Block;
 import net.minecraft.world.level.block.Blocks;
@@ -89,9 +90,12 @@ import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.*;
 import java.util.List;
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import ca.spottedleaf.moonrise.patches.chunk_system.io.MoonriseRegionFileIO;
 
 public class NMSBinding implements INMSBinding {
     private final KMap<Biome, Object> baseBiomeCache = new KMap<>();
@@ -412,6 +416,43 @@ public class NMSBinding implements INMSBinding {
         return keys;
     }
 
+    @Override
+    public KList<String> getReachableStructureKeys(World world) {
+        KList<String> keys = new KList<>();
+        try {
+            ServerLevel level = ((CraftWorld) world).getHandle();
+            BiomeSource source = level.getChunkSource().getGenerator().getBiomeSource();
+            keys.addAll(VanillaStructureBiomes.reachableStructureKeys(level, source));
+        } catch (Throwable e) {
+            Iris.reportError(e);
+        }
+        return keys;
+    }
+
+    @Override
+    public KList<String> getStructureBiomeKeys(String structureKey) {
+        KList<String> keys = new KList<>();
+        try {
+            keys.addAll(VanillaStructureBiomes.structureBiomeKeys(registry(), structureKey));
+        } catch (Throwable e) {
+            Iris.reportError(e);
+        }
+        return keys;
+    }
+
+    @Override
+    public KList<String> getPossibleBiomeKeys(World world) {
+        KList<String> keys = new KList<>();
+        try {
+            ServerLevel level = ((CraftWorld) world).getHandle();
+            BiomeSource source = level.getChunkSource().getGenerator().getBiomeSource();
+            keys.addAll(VanillaStructureBiomes.possibleBiomeKeys(source));
+        } catch (Throwable e) {
+            Iris.reportError(e);
+        }
+        return keys;
+    }
+
     @Override
     public boolean isBukkit() {
         return true;
@@ -555,6 +596,42 @@ public class NMSBinding implements INMSBinding {
         });
     }
 
+    @Override
+    public boolean purgeChunk(World world, int x, int z) {
+        ServerLevel level = ((CraftWorld) world).getHandle();
+        try {
+            CountDownLatch latch = new CountDownLatch(1);
+            Runnable unload = () -> {
+                try {
+                    if (world.isChunkLoaded(x, z)) {
+                        world.unloadChunk(x, z, false);
+                    }
+                } finally {
+                    latch.countDown();
+                }
+            };
+            if (!J.runRegion(world, x, z, unload)) {
+                return false;
+            }
+            if (!latch.await(15, TimeUnit.SECONDS)) {
+                Iris.warn("Chunk purge timed out waiting to unload " + x + "," + z + " in " + world.getName() + ".");
+                return false;
+            }
+
+            for (MoonriseRegionFileIO.RegionFileType type : MoonriseRegionFileIO.RegionFileType.values()) {
+                MoonriseRegionFileIO.scheduleSave(level, x, z, null, type);
+            }
+            MoonriseRegionFileIO.flush(level);
+            return true;
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            return false;
+        } catch (Throwable e) {
+            Iris.reportError(e);
+            return false;
+        }
+    }
+
     public ItemStack applyCustomNbt(ItemStack itemStack, KMap<String, Object> customNbt) throws IllegalArgumentException {
         if (customNbt != null && !customNbt.isEmpty()) {
             net.minecraft.world.item.ItemStack s = CraftItemStack.asNMSCopy(itemStack);

nms/v26_1_R1/src/main/java/art/arcane/iris/core/nms/v26_1_R1/VanillaStructureBiomes.java

@@ -0,0 +1,77 @@
+package art.arcane.iris.core.nms.v26_1_R1;
+
+import net.minecraft.core.Holder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.BiomeSource;
+import net.minecraft.world.level.levelgen.structure.Structure;
+
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+
+final class VanillaStructureBiomes {
+    private VanillaStructureBiomes() {
+    }
+
+    static Set<String> possibleBiomeKeys(BiomeSource source) {
+        Set<String> keys = new LinkedHashSet<>();
+        if (source == null) {
+            return keys;
+        }
+        for (Holder<Biome> holder : source.possibleBiomes()) {
+            Optional<ResourceKey<Biome>> key = holder.unwrapKey();
+            if (key.isPresent()) {
+                keys.add(key.get().identifier().toString());
+            }
+        }
+        return keys;
+    }
+
+    static Set<String> structureBiomeKeys(RegistryAccess access, String structureKey) {
+        Set<String> keys = new LinkedHashSet<>();
+        if (access == null || structureKey == null || structureKey.isEmpty()) {
+            return keys;
+        }
+        Registry<Structure> registry = access.lookupOrThrow(Registries.STRUCTURE);
+        Structure structure = registry.getValue(Identifier.parse(structureKey));
+        if (structure == null) {
+            return keys;
+        }
+        for (Holder<Biome> holder : structure.biomes()) {
+            Optional<ResourceKey<Biome>> key = holder.unwrapKey();
+            if (key.isPresent()) {
+                keys.add(key.get().identifier().toString());
+            }
+        }
+        return keys;
+    }
+
+    static Set<String> reachableStructureKeys(ServerLevel level, BiomeSource source) {
+        Set<String> reachable = new LinkedHashSet<>();
+        if (level == null || source == null) {
+            return reachable;
+        }
+        Set<String> possible = possibleBiomeKeys(source);
+        if (possible.isEmpty()) {
+            return reachable;
+        }
+        Registry<Structure> registry = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        for (Map.Entry<ResourceKey<Structure>, Structure> entry : registry.entrySet()) {
+            for (Holder<Biome> holder : entry.getValue().biomes()) {
+                Optional<ResourceKey<Biome>> key = holder.unwrapKey();
+                if (key.isPresent() && possible.contains(key.get().identifier().toString())) {
+                    reachable.add(entry.getKey().identifier().toString());
+                    break;
+                }
+            }
+        }
+        return reachable;
+    }
+}