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

@@ -0,0 +1,401 @@
+package art.arcane.iris.core.nms.v26_2_R1;
+
+import com.mojang.serialization.MapCodec;
+import art.arcane.iris.spi.IrisLogging;
+import art.arcane.iris.engine.data.cache.AtomicCache;
+import art.arcane.iris.engine.framework.Engine;
+import art.arcane.iris.engine.object.IrisBiome;
+import art.arcane.iris.engine.object.IrisBiomeCustom;
+import art.arcane.volmlib.util.collection.KMap;
+import art.arcane.volmlib.util.math.RNG;
+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.world.level.biome.Biome;
+import net.minecraft.world.level.biome.BiomeSource;
+import net.minecraft.world.level.biome.Climate;
+import org.bukkit.Bukkit;
+import org.bukkit.World;
+import org.bukkit.craftbukkit.CraftServer;
+import org.bukkit.craftbukkit.CraftWorld;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Stream;
+
+public class CustomBiomeSource extends BiomeSource {
+    private static final int NOISE_BIOME_CACHE_MAX = 262144;
+
+    private final long seed;
+    private final Engine engine;
+    private final Registry<Biome> biomeCustomRegistry;
+    private final Registry<Biome> biomeRegistry;
+    private final AtomicCache<RegistryAccess> registryAccess = new AtomicCache<>();
+    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;
+        this.seed = seed;
+        this.biomeCustomRegistry = registry().lookup(Registries.BIOME).orElse(null);
+        this.biomeRegistry = ((RegistryAccess) getFor(RegistryAccess.Frozen.class, ((CraftServer) Bukkit.getServer()).getHandle().getServer())).lookup(Registries.BIOME).orElse(null);
+        this.fallbackBiome = resolveFallbackBiome(this.biomeRegistry, this.biomeCustomRegistry);
+        this.customBiomes = fillCustomBiomes(this.biomeCustomRegistry, engine, this.fallbackBiome);
+    }
+
+    private static List<Holder<Biome>> getAllBiomes(Registry<Biome> customRegistry, Registry<Biome> registry, Engine engine, Holder<Biome> fallback) {
+        LinkedHashSet<Holder<Biome>> biomes = new LinkedHashSet<>();
+        if (fallback != null) {
+            biomes.add(fallback);
+        }
+
+        for (IrisBiome i : engine.getAllBiomes()) {
+            Holder<Biome> vanillaHolder = NMSBinding.biomeToBiomeBase(registry, i.getVanillaDerivative());
+            if (vanillaHolder != null) {
+                biomes.add(vanillaHolder);
+            } else if (!i.isCustom() && fallback != null) {
+                biomes.add(fallback);
+            }
+
+            if (i.isCustom()) {
+                for (IrisBiomeCustom j : i.getCustomDerivitives()) {
+                    Holder<Biome> customHolder = resolveCustomBiomeHolder(customRegistry, engine, j.getId());
+                    if (customHolder != null) {
+                        biomes.add(customHolder);
+                    } else if (fallback != null) {
+                        biomes.add(fallback);
+                    }
+                }
+            }
+        }
+
+        return new ArrayList<>(biomes);
+    }
+
+    private static Object getFor(Class<?> type, Object source) {
+        Object o = fieldFor(type, source);
+
+        if (o != null) {
+            return o;
+        }
+
+        return invokeFor(type, source);
+    }
+
+    private static Object fieldFor(Class<?> returns, Object in) {
+        return fieldForClass(returns, in.getClass(), in);
+    }
+
+    private static Object invokeFor(Class<?> returns, Object in) {
+        for (Method i : in.getClass().getMethods()) {
+            if (i.getReturnType().equals(returns)) {
+                i.setAccessible(true);
+                try {
+                    IrisLogging.debug("[NMS] Found " + returns.getSimpleName() + " in " + in.getClass().getSimpleName() + "." + i.getName() + "()");
+                    return i.invoke(in);
+                } catch (Throwable e) {
+                    e.printStackTrace();
+                }
+            }
+        }
+
+        return null;
+    }
+
+    @SuppressWarnings("unchecked")
+    private static <T> T fieldForClass(Class<T> returnType, Class<?> sourceType, Object in) {
+        for (Field i : sourceType.getDeclaredFields()) {
+            if (i.getType().equals(returnType)) {
+                i.setAccessible(true);
+                try {
+                    IrisLogging.debug("[NMS] Found " + returnType.getSimpleName() + " in " + sourceType.getSimpleName() + "." + i.getName());
+                    return (T) i.get(in);
+                } catch (IllegalAccessException e) {
+                    e.printStackTrace();
+                }
+            }
+        }
+        return null;
+    }
+
+    @Override
+    protected Stream<Holder<Biome>> collectPossibleBiomes() {
+        return getAllBiomes(
+                ((RegistryAccess) getFor(RegistryAccess.Frozen.class, ((CraftServer) Bukkit.getServer()).getHandle().getServer()))
+                        .lookup(Registries.BIOME).orElse(null),
+                ((CraftWorld) engine.getWorld().realWorld()).getHandle().registryAccess().lookup(Registries.BIOME).orElse(null),
+                engine,
+                fallbackBiome).stream();
+    }
+
+    private KMap<String, Holder<Biome>> fillCustomBiomes(Registry<Biome> customRegistry, Engine engine, Holder<Biome> fallback) {
+        KMap<String, Holder<Biome>> m = new KMap<>();
+        if (customRegistry == null) {
+            return m;
+        }
+
+        for (IrisBiome i : engine.getAllBiomes()) {
+            if (i.isCustom()) {
+                for (IrisBiomeCustom j : i.getCustomDerivitives()) {
+                    Holder<Biome> holder = resolveCustomBiomeHolder(customRegistry, engine, j.getId());
+                    if (holder == null) {
+                        if (fallback != null) {
+                            m.put(j.getId(), fallback);
+                        }
+                        IrisLogging.error("Cannot find biome for IrisBiomeCustom " + j.getId() + " from engine " + engine.getName());
+                        continue;
+                    }
+                    m.put(j.getId(), holder);
+                }
+            }
+        }
+
+        return m;
+    }
+
+    private RegistryAccess registry() {
+        return registryAccess.aquire(() -> (RegistryAccess) getFor(RegistryAccess.Frozen.class, ((CraftServer) Bukkit.getServer()).getHandle().getServer()));
+    }
+
+    @Override
+    protected MapCodec<? extends BiomeSource> codec() {
+        throw new UnsupportedOperationException("Not supported");
+    }
+
+    @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 = resolveVisibleBiomeHolder(x, y, z);
+        Holder<Biome> existingHolder = noiseBiomeCache.putIfAbsent(cacheKey, resolvedHolder);
+        if (existingHolder != null) {
+            return existingHolder;
+        }
+
+        if (noiseBiomeCache.size() > NOISE_BIOME_CACHE_MAX) {
+            noiseBiomeCache.clear();
+        }
+
+        return resolvedHolder;
+    }
+
+    private Holder<Biome> resolveStructureBiomeHolder(int x, int y, int z) {
+        BiomeResolution resolution = resolveBiomeResolution(x, y, z);
+        if (resolution == null) {
+            return getFallbackBiome();
+        }
+
+        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, resolution.irisBiome.getVanillaDerivative());
+        if (holder != null) {
+            return holder;
+        }
+
+        if (resolution.irisBiome.isCustom()) {
+            return resolveCustomHolder(resolution);
+        }
+
+        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;
+        int worldMinHeight = engine.getWorld().minHeight();
+        int internalY = blockY - worldMinHeight;
+        int surfaceInternalY = engine.getComplex().getHeightStream().get(blockX, blockZ).intValue();
+        int caveSwitchInternalY = Math.max(-8 - worldMinHeight, 40);
+        boolean deepUnderground = internalY <= caveSwitchInternalY;
+        boolean belowSurface = internalY <= surfaceInternalY - 8;
+        boolean underground = deepUnderground && belowSurface;
+        IrisBiome irisBiome = underground
+                ? engine.getCaveBiome(blockX, internalY, blockZ)
+                : engine.getComplex().getTrueBiomeStream().get(blockX, blockZ);
+        if (irisBiome == null && underground) {
+            irisBiome = engine.getComplex().getTrueBiomeStream().get(blockX, blockZ);
+        }
+        if (irisBiome == null) {
+            return null;
+        }
+
+        RNG noiseRng = new RNG(seed
+                ^ (((long) blockX) * 341873128712L)
+                ^ (((long) blockY) * 132897987541L)
+                ^ (((long) blockZ) * 42317861L));
+
+        return new BiomeResolution(irisBiome, underground, blockX, blockY, blockZ, noiseRng);
+    }
+
+    private Holder<Biome> getFallbackBiome() {
+        if (fallbackBiome != null) {
+            return fallbackBiome;
+        }
+
+        Holder<Biome> holder = resolveFallbackBiome(biomeRegistry, biomeCustomRegistry);
+        if (holder != null) {
+            return holder;
+        }
+
+        throw new IllegalStateException("Unable to resolve any biome holder fallback for Iris biome source");
+    }
+
+    private static long packNoiseKey(int x, int y, int z) {
+        return (((long) x & 67108863L) << 38)
+                | (((long) z & 67108863L) << 12)
+                | ((long) y & 4095L);
+    }
+
+    private static Holder<Biome> resolveCustomBiomeHolder(Registry<Biome> customRegistry, Engine engine, String customBiomeId) {
+        if (customRegistry == null || engine == null || customBiomeId == null || customBiomeId.isBlank()) {
+            return null;
+        }
+
+        Identifier resourceLocation = Identifier.fromNamespaceAndPath(
+                engine.getDimension().getLoadKey().toLowerCase(java.util.Locale.ROOT),
+                customBiomeId.toLowerCase(java.util.Locale.ROOT)
+        );
+        Biome biome = customRegistry.getValue(resourceLocation);
+        if (biome == null) {
+            return null;
+        }
+
+        Optional<ResourceKey<Biome>> optionalBiomeKey = customRegistry.getResourceKey(biome);
+        if (optionalBiomeKey.isEmpty()) {
+            return null;
+        }
+
+        Optional<Holder.Reference<Biome>> optionalReferenceHolder = customRegistry.get(optionalBiomeKey.get());
+        if (optionalReferenceHolder.isEmpty()) {
+            return null;
+        }
+
+        return optionalReferenceHolder.get();
+    }
+
+    private static Holder<Biome> resolveFallbackBiome(Registry<Biome> registry, Registry<Biome> customRegistry) {
+        Holder<Biome> plains = NMSBinding.biomeToBiomeBase(registry, org.bukkit.block.Biome.PLAINS);
+        if (plains != null) {
+            return plains;
+        }
+
+        Holder<Biome> vanilla = firstHolder(registry);
+        if (vanilla != null) {
+            return vanilla;
+        }
+
+        return firstHolder(customRegistry);
+    }
+
+    private static Holder<Biome> firstHolder(Registry<Biome> registry) {
+        if (registry == null) {
+            return null;
+        }
+
+        for (Biome biome : registry) {
+            Optional<ResourceKey<Biome>> optionalBiomeKey = registry.getResourceKey(biome);
+            if (optionalBiomeKey.isEmpty()) {
+                continue;
+            }
+
+            Optional<Holder.Reference<Biome>> optionalHolder = registry.get(optionalBiomeKey.get());
+            if (optionalHolder.isPresent()) {
+                return optionalHolder.get();
+            }
+        }
+
+        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;
+        }
+    }
+}

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

@@ -0,0 +1,407 @@
+package art.arcane.iris.core.nms.v26_2_R1;
+
+import com.mojang.datafixers.util.Pair;
+import com.mojang.serialization.MapCodec;
+import art.arcane.iris.spi.IrisLogging;
+import art.arcane.iris.engine.framework.Engine;
+import art.arcane.iris.engine.object.IrisImportedStructureControl;
+import art.arcane.iris.util.common.reflect.WrappedField;
+import art.arcane.iris.util.common.reflect.WrappedReturningMethod;
+import net.minecraft.core.*;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.WorldGenRegion;
+import net.minecraft.util.random.WeightedList;
+import net.minecraft.world.entity.MobCategory;
+import net.minecraft.world.level.*;
+import net.minecraft.world.level.biome.*;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.ChunkAccess;
+import net.minecraft.world.level.chunk.ChunkGenerator;
+import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
+import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureSet;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
+import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import net.minecraft.core.registries.Registries;
+import java.util.stream.Collectors;
+import art.arcane.iris.engine.framework.IrisStructureLocator;
+import org.bukkit.World;
+import org.bukkit.craftbukkit.CraftWorld;
+import org.bukkit.craftbukkit.generator.CustomChunkGenerator;
+import org.spigotmc.SpigotWorldConfig;
+
+import javax.annotation.Nullable;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.*;
+import java.util.concurrent.CompletableFuture;
+
+public class IrisChunkGenerator extends CustomChunkGenerator {
+    private static final WrappedField<ChunkGenerator, BiomeSource> BIOME_SOURCE;
+    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) {
+        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), world.getGenerator());
+        this.delegate = delegate;
+        this.engine = engine;
+        this.customBiomeSource = customBiomeSource;
+    }
+
+    @Override
+    public @Nullable Pair<BlockPos, Holder<Structure>> findNearestMapStructure(ServerLevel level, HolderSet<Structure> holders, BlockPos pos, int radius, boolean findUnexplored) {
+        try {
+            Registry<Structure> registry = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+            BlockPos best = null;
+            Holder<Structure> bestHolder = null;
+            long bestDist = Long.MAX_VALUE;
+            for (Holder<Structure> holder : holders) {
+                Object id = registry.getKey(holder.value());
+                if (id == null) {
+                    continue;
+                }
+                int[] at = IrisStructureLocator.locate(engine, id.toString(), pos.getX(), pos.getZ(), Math.max(1, radius));
+                if (at == null) {
+                    continue;
+                }
+                long dx = (long) at[0] - pos.getX();
+                long dz = (long) at[2] - pos.getZ();
+                long d = dx * dx + dz * dz;
+                if (d < bestDist) {
+                    bestDist = d;
+                    best = new BlockPos(at[0], at[1], at[2]);
+                    bestHolder = holder;
+                }
+            }
+            if (best != null) {
+                return Pair.of(best, bestHolder);
+            }
+        } catch (Throwable e) {
+            IrisLogging.reportError(e);
+        }
+        if (!importedControl().active()) {
+            return null;
+        }
+        HolderSet<Structure> reachable = filterReachableStructures(level, holders);
+        if (reachable == null || reachable.size() == 0) {
+            return null;
+        }
+        try {
+            return delegate.findNearestMapStructure(level, reachable, pos, radius, findUnexplored);
+        } catch (Throwable e) {
+            IrisLogging.error("Vanilla structure locate failed near " + pos.getX() + ", " + pos.getZ() + ": " + e);
+            IrisLogging.reportError(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);
+    }
+
+    @Override
+    public ChunkGenerator getDelegate() {
+        if (delegate instanceof CustomChunkGenerator chunkGenerator)
+            return chunkGenerator.getDelegate();
+        return delegate;
+    }
+
+    @Override
+    public int getMinY() {
+        return delegate.getMinY();
+    }
+
+    @Override
+    public int getSeaLevel() {
+        return delegate.getSeaLevel();
+    }
+
+    @Override
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager, ResourceKey<Level> levelKey) {
+        if (!importedControl().active()) {
+            return;
+        }
+        super.createStructures(registryAccess, structureState, structureManager, access, templateManager, levelKey);
+    }
+
+    private IrisImportedStructureControl importedControl() {
+        return engine.getDimension().getImportedStructures();
+    }
+
+    @Override
+    public ChunkGeneratorStructureState createState(HolderLookup<StructureSet> holderlookup, RandomState randomstate, long i, SpigotWorldConfig conf) {
+        return delegate.createState(holderlookup, randomstate, i, conf);
+    }
+
+    @Override
+    public void createReferences(WorldGenLevel generatoraccessseed, StructureManager structuremanager, ChunkAccess ichunkaccess) {
+        delegate.createReferences(generatoraccessseed, structuremanager, ichunkaccess);
+    }
+
+    @Override
+    public CompletableFuture<ChunkAccess> createBiomes(RandomState randomstate, Blender blender, StructureManager structuremanager, ChunkAccess ichunkaccess) {
+        ichunkaccess.fillBiomesFromNoise(customBiomeSource::getVisibleNoiseBiome, randomstate.sampler());
+        return CompletableFuture.completedFuture(ichunkaccess);
+    }
+
+    @Override
+    public void buildSurface(WorldGenRegion regionlimitedworldaccess, StructureManager structuremanager, RandomState randomstate, ChunkAccess ichunkaccess) {
+        delegate.buildSurface(regionlimitedworldaccess, structuremanager, randomstate, ichunkaccess);
+    }
+
+    @Override
+    public void applyCarvers(WorldGenRegion regionlimitedworldaccess, long seed, RandomState randomstate, BiomeManager biomemanager, StructureManager structuremanager, ChunkAccess ichunkaccess) {
+        delegate.applyCarvers(regionlimitedworldaccess, seed, randomstate, biomemanager, structuremanager, ichunkaccess);
+    }
+
+    @Override
+    public CompletableFuture<ChunkAccess> fillFromNoise(Blender blender, RandomState randomstate, StructureManager structuremanager, ChunkAccess ichunkaccess) {
+        return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
+    }
+
+    @Override
+    public WeightedList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
+        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void addDebugScreenInfo(List<String> list, RandomState randomstate, BlockPos blockposition) {
+        delegate.addDebugScreenInfo(list, randomstate, blockposition);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        if (importedControl().active()) {
+            placeVanillaStructures(generatoraccessseed, ichunkaccess, structuremanager);
+        }
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    private void placeVanillaStructures(WorldGenLevel world, ChunkAccess chunk, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures()) {
+            return;
+        }
+        ChunkPos chunkPos = chunk.getPos();
+        SectionPos sectionPos = SectionPos.of(chunkPos, world.getMinSectionY());
+        BlockPos origin = sectionPos.origin();
+        Registry<Structure> registry = world.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        Map<Integer, List<Structure>> byStep = registry.stream().collect(Collectors.groupingBy(s -> s.step().ordinal()));
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long decoSeed = random.setDecorationSeed(world.getSeed(), origin.getX(), origin.getZ());
+        BoundingBox area = writableArea(chunk);
+        int steps = GenerationStep.Decoration.values().length;
+        IrisImportedStructureControl control = importedControl();
+        for (int step = 0; step < steps; step++) {
+            int index = 0;
+            for (Structure structure : byStep.getOrDefault(step, List.of())) {
+                Object id = registry.getKey(structure);
+                String structureId = id == null ? null : id.toString();
+                if (control.shouldGenerate(structureId) && !IrisStructureLocator.suppressesVanilla(engine, structureId)) {
+                    random.setFeatureSeed(decoSeed, index, step);
+                    int[] offset = control.resolveOffset(structureId, isUndergroundStep(structure.step()));
+                    boolean shifted = offset[0] != 0 || offset[1] != 0 || offset[2] != 0;
+                    WorldGenLevel target = shifted ? shiftedLevel(world, offset[0], offset[1], offset[2]) : world;
+                    BoundingBox placeArea = shifted
+                            ? new BoundingBox(area.minX() - offset[0], area.minY(), area.minZ() - offset[2], area.maxX() - offset[0], area.maxY(), area.maxZ() - offset[2])
+                            : area;
+                    try {
+                        structureManager.startsForStructure(sectionPos, structure)
+                                .forEach(start -> start.placeInChunk(target, structureManager, this, random, placeArea, chunkPos));
+                    } catch (Throwable e) {
+                        IrisLogging.reportError(e);
+                    }
+                }
+                index++;
+            }
+        }
+    }
+
+    private static boolean isUndergroundStep(GenerationStep.Decoration step) {
+        return step == GenerationStep.Decoration.UNDERGROUND_STRUCTURES
+                || step == GenerationStep.Decoration.STRONGHOLDS;
+    }
+
+    private WorldGenLevel shiftedLevel(WorldGenLevel world, int dx, int dy, int dz) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                WorldGenLevel.class.getClassLoader(),
+                new Class<?>[]{WorldGenLevel.class},
+                (proxy, method, args) -> {
+                    if (args != null) {
+                        for (int i = 0; i < args.length; i++) {
+                            if (args[i] instanceof BlockPos bp) {
+                                args[i] = new BlockPos(bp.getX() + dx, bp.getY() + dy, bp.getZ() + dz);
+                            }
+                        }
+                    }
+                    try {
+                        return method.invoke(world, args);
+                    } catch (InvocationTargetException e) {
+                        throw e.getCause();
+                    }
+                });
+    }
+
+    private BoundingBox writableArea(ChunkAccess chunk) {
+        ChunkPos cp = chunk.getPos();
+        int i = cp.getMinBlockX();
+        int j = cp.getMinBlockZ();
+        int minY = getMinY() + 1;
+        int maxY = getMinY() + engine.getHeight() - 1;
+        return new BoundingBox(i, minY, j, i + 15, maxY, j + 15);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+
+        Heightmap surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        Heightmap ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        Heightmap motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        Heightmap motionNoLeaves = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES);
+
+        for (int x = 0; x < 16; x++) {
+            for (int z = 0; z < 16; z++) {
+                int wX = x + blockPos.getX();
+                int wZ = z + blockPos.getZ();
+
+                int terrainTop = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int terrainNoFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, terrainNoFluid);
+                SET_HEIGHT.invoke(surface, x, z, terrainTop);
+                SET_HEIGHT.invoke(motion, x, z, terrainTop);
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, terrainTop);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
+    }
+
+    @Override
+    public void spawnOriginalMobs(WorldGenRegion regionlimitedworldaccess) {
+        delegate.spawnOriginalMobs(regionlimitedworldaccess);
+    }
+
+    @Override
+    public int getSpawnHeight(LevelHeightAccessor levelheightaccessor) {
+        return delegate.getSpawnHeight(levelheightaccessor);
+    }
+
+    @Override
+    public int getGenDepth() {
+        return delegate.getGenDepth();
+    }
+
+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinY() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
+    @Override
+    public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        int block = engine.getHeight(i, j, true);
+        int water = engine.getHeight(i, j, false);
+        BlockState[] column = new BlockState[levelheightaccessor.getHeight()];
+        for (int k = 0; k < column.length; k++) {
+            if (k <= block) column[k] = Blocks.STONE.defaultBlockState();
+            else if (k <= water) column[k] = Blocks.WATER.defaultBlockState();
+            else column[k] = Blocks.AIR.defaultBlockState();
+        }
+        return new NoiseColumn(levelheightaccessor.getMinY(), column);
+    }
+
+    @Override
+    public Optional<Identifier> getTypeNameForDataFixer() {
+        return delegate.getTypeNameForDataFixer();
+    }
+
+    @Override
+    public void validate() {
+        delegate.validate();
+    }
+
+    static {
+        Field biomeSource = null;
+        for (Field field : ChunkGenerator.class.getDeclaredFields()) {
+            if (!field.getType().equals(BiomeSource.class))
+                continue;
+            biomeSource = field;
+            break;
+        }
+        if (biomeSource == null)
+            throw new RuntimeException("Could not find biomeSource field in ChunkGenerator!");
+
+        Method setHeight = null;
+        for (Method method : Heightmap.class.getDeclaredMethods()) {
+            var types = method.getParameterTypes();
+            if (types.length != 3 || !Arrays.equals(types, new Class<?>[]{int.class, int.class, int.class})
+                    || !method.getReturnType().equals(void.class))
+                continue;
+            setHeight = method;
+            break;
+        }
+        if (setHeight == null)
+            throw new RuntimeException("Could not find setHeight method in Heightmap!");
+
+        BIOME_SOURCE = new WrappedField<>(ChunkGenerator.class, biomeSource.getName());
+        SET_HEIGHT = new WrappedReturningMethod<>(Heightmap.class, setHeight.getName(), setHeight.getParameterTypes());
+    }
+
+    private static ChunkGenerator edit(ChunkGenerator generator, BiomeSource source) {
+        try {
+            BIOME_SOURCE.set(generator, source);
+            if (generator instanceof CustomChunkGenerator custom)
+                BIOME_SOURCE.set(custom.getDelegate(), source);
+
+            return generator;
+        } catch (IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}

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

@@ -0,0 +1,77 @@
+package art.arcane.iris.core.nms.v26_2_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;
+    }
+}