Allow placing datapack structures in Iris worlds (#1225)

* Allow placing datapack structures in Iris worlds * command for generating configs for datapack structures * remove the sub dir from the snippet key
2026-02-16 02:20:44 +00:00 · 2025-09-07 18:36:08 +02:00
parent aa14242b54
commit a8ee321eb8
35 changed files with 2718 additions and 265 deletions
--- a/nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/IrisChunkGenerator.java
+++ b/nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/IrisChunkGenerator.java
@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,45 +29,55 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+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.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_20_R1.CraftWorld;
 import org.bukkit.craftbukkit.v1_20_R1.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_20_R1.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -182,8 +194,58 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var structure = registry.getOptional(loc).orElse(null);
+            if (structure == null) return false;
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure, registryAccess),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -201,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(executor, blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -213,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.POST_FEATURES);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -236,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.getGenDepth();
    }

+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
    @Override
    public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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.getMinBuildHeight(), column);
    }

    static {
@@ -251,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/NMSBinding.java
+++ b/nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/NMSBinding.java
@@ -3,11 +3,14 @@ package com.volmit.iris.core.nms.v1_20_R1;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.datafixers.util.Pair;
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.agent.Agent;
 import com.volmit.iris.util.collection.KList;
@@ -59,6 +62,8 @@ import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import org.bukkit.*;
 import org.bukkit.block.Biome;
 import org.bukkit.block.data.BlockData;
@@ -79,7 +84,6 @@ import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;

-import java.awt.*;
 import java.awt.Color;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
@@ -90,6 +94,7 @@ import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;

 public class NMSBinding implements INMSBinding {

@@ -704,6 +709,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.registryKeySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");
--- a/nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/IrisChunkGenerator.java
+++ b/nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/IrisChunkGenerator.java
@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,45 +29,55 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+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.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_20_R2.CraftWorld;
 import org.bukkit.craftbukkit.v1_20_R2.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_20_R2.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -182,8 +194,58 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var structure = registry.getOptional(loc).orElse(null);
+            if (structure == null) return false;
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure, registryAccess),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -201,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(executor, blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -213,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.POST_FEATURES);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -236,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.getGenDepth();
    }

+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
    @Override
    public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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.getMinBuildHeight(), column);
    }

    static {
@@ -251,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/NMSBinding.java
+++ b/nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/NMSBinding.java
@@ -1,9 +1,26 @@
 package com.volmit.iris.core.nms.v1_20_R2;

 import com.mojang.brigadier.exceptions.CommandSyntaxException;
+import java.awt.Color;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 import com.mojang.datafixers.util.Pair;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.engine.data.cache.AtomicCache;
@@ -21,6 +38,8 @@ import com.volmit.iris.util.matter.MatterBiomeInject;
 import com.volmit.iris.util.nbt.mca.NBTWorld;
 import com.volmit.iris.util.nbt.mca.palette.*;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
+import com.volmit.iris.core.nms.container.StructurePlacement;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.util.scheduling.J;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import net.bytebuddy.ByteBuddy;
@@ -58,6 +77,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -707,6 +728,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.registryKeySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");
--- a/nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/IrisChunkGenerator.java
+++ b/nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/IrisChunkGenerator.java
@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,45 +29,55 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+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.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.levelgen.*;
 import net.minecraft.world.level.levelgen.blending.Blender;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_20_R3.CraftWorld;
 import org.bukkit.craftbukkit.v1_20_R3.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_20_R3.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -182,8 +194,58 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var structure = registry.getOptional(loc).orElse(null);
+            if (structure == null) return false;
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -201,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(executor, blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -213,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.POST_FEATURES);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -236,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.getGenDepth();
    }

+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
    @Override
    public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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.getMinBuildHeight(), column);
    }

    static {
@@ -251,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/NMSBinding.java
+++ b/nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/NMSBinding.java
@@ -1,9 +1,26 @@
 package com.volmit.iris.core.nms.v1_20_R3;

+import java.awt.Color;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.datafixers.util.Pair;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.engine.data.cache.AtomicCache;
@@ -21,6 +38,8 @@ import com.volmit.iris.util.matter.MatterBiomeInject;
 import com.volmit.iris.util.nbt.mca.NBTWorld;
 import com.volmit.iris.util.nbt.mca.palette.*;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
+import com.volmit.iris.core.nms.container.StructurePlacement;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.util.scheduling.J;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import net.bytebuddy.ByteBuddy;
@@ -58,6 +77,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -708,6 +729,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.registryKeySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");
--- a/nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/IrisChunkGenerator.java
+++ b/nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/IrisChunkGenerator.java
@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,43 +29,53 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+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.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+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.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_20_R4.CraftWorld;
 import org.bukkit.craftbukkit.v1_20_R4.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_20_R4.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.*;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -180,8 +192,59 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.getHolder(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -199,11 +262,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(executor, blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -211,7 +269,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.POST_FEATURES);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -234,9 +360,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.getGenDepth();
    }

+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
    @Override
    public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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.getMinBuildHeight(), column);
    }

    static {
@@ -249,7 +388,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/NMSBinding.java
+++ b/nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/NMSBinding.java
@@ -1,11 +1,25 @@
 package com.volmit.iris.core.nms.v1_20_R4;

+import java.awt.Color;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.datafixers.util.Pair;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
@@ -21,6 +35,7 @@ import com.volmit.iris.util.math.Vector3d;
 import com.volmit.iris.util.matter.MatterBiomeInject;
 import com.volmit.iris.util.nbt.mca.NBTWorld;
 import com.volmit.iris.util.nbt.mca.palette.*;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
 import com.volmit.iris.util.scheduling.J;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
@@ -59,6 +74,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -726,6 +743,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");
--- a/nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/IrisChunkGenerator.java
+++ b/nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/IrisChunkGenerator.java
@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,44 +29,54 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+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.levelgen.GenerationStep;
-import net.minecraft.world.level.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+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.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R1.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R1.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R1.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -181,8 +193,59 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.registryOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.getHolder(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -200,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -212,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSection());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().registryOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinBuildHeight() + 1;
+        int maxY = heightAccessor.getMaxBuildHeight() - 1;
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -235,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.getGenDepth();
    }

+    @Override
+    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
+        return levelheightaccessor.getMinBuildHeight() + engine.getHeight(i, j, !heightmap_type.isOpaque().test(Blocks.WATER.defaultBlockState())) + 1;
+    }
+
    @Override
    public NoiseColumn getBaseColumn(int i, int j, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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.getMinBuildHeight(), column);
    }

    static {
@@ -250,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/NMSBinding.java
+++ b/nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/NMSBinding.java
@@ -1,12 +1,31 @@
 package com.volmit.iris.core.nms.v1_21_R1;

+import java.awt.Color;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.datafixers.util.Pair;
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.BlockProperty;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
@@ -63,6 +82,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -737,6 +758,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().registryOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().registryOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::getHolder)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new com.volmit.iris.core.nms.container.Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(com.volmit.iris.core.nms.container.Pair::getA, com.volmit.iris.core.nms.container.Pair::getB, (a, b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");
--- a/nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/IrisChunkGenerator.java
+++ b/nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/IrisChunkGenerator.java
@@ -8,16 +8,18 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
-import net.minecraft.core.BlockPos;
-import net.minecraft.core.Holder;
-import net.minecraft.core.HolderSet;
-import net.minecraft.core.RegistryAccess;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
+import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -27,43 +29,54 @@ import net.minecraft.tags.StructureTags;
 import net.minecraft.tags.TagKey;
 import net.minecraft.util.random.WeightedRandomList;
 import net.minecraft.world.entity.MobCategory;
-import net.minecraft.world.level.LevelHeightAccessor;
-import net.minecraft.world.level.NoiseColumn;
-import net.minecraft.world.level.StructureManager;
-import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.*;
 import net.minecraft.world.level.biome.Biome;
 import net.minecraft.world.level.biome.BiomeManager;
 import net.minecraft.world.level.biome.BiomeSource;
 import net.minecraft.world.level.biome.MobSpawnSettings;
+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.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+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.BoundingBox;
 import net.minecraft.world.level.levelgen.structure.Structure;
+import net.minecraft.world.level.levelgen.structure.StructureStart;
 import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R2.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R2.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R2.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -180,8 +193,59 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.lookupOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.get(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    (biome) -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -199,11 +263,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -211,7 +270,75 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
+    }
+
+    @Override
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
+    }
+
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinY() + 1;
+        int maxY = heightAccessor.getMaxY();
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -234,9 +361,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        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) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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);
    }

    static {
@@ -249,7 +389,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/NMSBinding.java
+++ b/nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/NMSBinding.java
@@ -1,9 +1,24 @@
 package com.volmit.iris.core.nms.v1_21_R2;

+import java.awt.Color;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import com.mojang.serialization.Lifecycle;
+import com.volmit.iris.core.link.Identifier;
+import com.volmit.iris.core.nms.container.AutoClosing;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
@@ -21,6 +36,7 @@ import com.volmit.iris.util.matter.MatterBiomeInject;
 import com.volmit.iris.util.nbt.mca.NBTWorld;
 import com.volmit.iris.util.nbt.mca.palette.*;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.util.scheduling.J;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import it.unimi.dsi.fastutil.shorts.ShortList;
@@ -60,6 +76,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -734,6 +752,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().lookupOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().lookupOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::get)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(Pair::getA, Pair::getB, (a, b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");
--- a/nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/IrisChunkGenerator.java
+++ b/nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/IrisChunkGenerator.java
@@ -8,12 +8,17 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
 import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
@@ -26,38 +31,49 @@ import net.minecraft.util.random.WeightedRandomList;
 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.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+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.BuiltinStructures;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
 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.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R3.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R3.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R3.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 import org.spigotmc.SpigotWorldConfig;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
-import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+import java.lang.reflect.Method;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -174,8 +190,61 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager, ResourceKey<Level> resourcekey) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager, resourcekey);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager, ResourceKey<Level> levelKey) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.lookupOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.get(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    holder,
+                    levelKey,
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    biome -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -208,11 +277,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -220,7 +284,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
    }

    @Override
@@ -230,22 +294,70 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, vanilla);
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
    }

    @Override
-    public int getFirstFreeHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstFreeHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
    }

-    @Override
-    public int getFirstOccupiedHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstOccupiedHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
-    @Override
-    public void addVanillaDecorations(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinY() + 1;
+        int maxY = heightAccessor.getMaxY();
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -263,9 +375,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        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) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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
@@ -294,7 +419,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/NMSBinding.java
+++ b/nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/NMSBinding.java
@@ -2,12 +2,17 @@ package com.volmit.iris.core.nms.v1_21_R3;

 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisJigsawStructure;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.agent.Agent;
 import com.volmit.iris.util.collection.KList;
@@ -61,6 +66,9 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.StructureSet;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -89,10 +97,16 @@ import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.*;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;

 public class NMSBinding implements INMSBinding {
    private final KMap<Biome, Object> baseBiomeCache = new KMap<>();
@@ -179,14 +193,14 @@ public class NMSBinding implements INMSBinding {
    }

    @Contract(value = "null, _, _ -> null", pure = true)
-    private Object convertFromTag(net.minecraft.nbt.Tag tag, int depth, int maxDepth) {
+    private Object convertFromTag(Tag tag, int depth, int maxDepth) {
        if (tag == null || depth > maxDepth) return null;
        return switch (tag) {
            case CollectionTag<?> collection -> {
                KList<Object> list = new KList<>();

                for (Object i : collection) {
-                    if (i instanceof net.minecraft.nbt.Tag t)
+                    if (i instanceof Tag t)
                        list.add(convertFromTag(t, depth + 1, maxDepth));
                    else list.add(i);
                }
@@ -243,7 +257,7 @@ public class NMSBinding implements INMSBinding {
                yield tag;
            }
            case List<?> list -> {
-                var tag = new net.minecraft.nbt.ListTag();
+                var tag = new ListTag();
                for (var i : list) {
                    tag.add(convertToTag(i, depth + 1, maxDepth));
                }
@@ -497,13 +511,13 @@ public class NMSBinding implements INMSBinding {
    @Override
    public MCAPaletteAccess createPalette() {
        MCAIdMapper<BlockState> registry = registryCache.aquireNasty(() -> {
-            Field cf = net.minecraft.core.IdMapper.class.getDeclaredField("tToId");
-            Field df = net.minecraft.core.IdMapper.class.getDeclaredField("idToT");
-            Field bf = net.minecraft.core.IdMapper.class.getDeclaredField("nextId");
+            Field cf = IdMapper.class.getDeclaredField("tToId");
+            Field df = IdMapper.class.getDeclaredField("idToT");
+            Field bf = IdMapper.class.getDeclaredField("nextId");
            cf.setAccessible(true);
            df.setAccessible(true);
            bf.setAccessible(true);
-            net.minecraft.core.IdMapper<BlockState> blockData = Block.BLOCK_STATE_REGISTRY;
+            IdMapper<BlockState> blockData = Block.BLOCK_STATE_REGISTRY;
            int b = bf.getInt(blockData);
            Object2IntMap<BlockState> c = (Object2IntMap<BlockState>) cf.get(blockData);
            List<BlockState> d = (List<BlockState>) df.get(blockData);
@@ -601,7 +615,7 @@ public class NMSBinding implements INMSBinding {
    }

    @Override
-    public java.awt.Color getBiomeColor(Location location, BiomeColor type) {
+    public Color getBiomeColor(Location location, BiomeColor type) {
        LevelReader reader = ((CraftWorld) location.getWorld()).getHandle();
        var holder = reader.getBiome(new BlockPos(location.getBlockX(), location.getBlockY(), location.getBlockZ()));
        var biome = holder.value();
@@ -734,6 +748,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().lookupOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().lookupOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::get)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(Pair::getA, Pair::getB, (a,b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");
--- a/nms/v1_21_R4/src/main/java/com/volmit/iris/core/nms/v1_21_R4/IrisChunkGenerator.java
+++ b/nms/v1_21_R4/src/main/java/com/volmit/iris/core/nms/v1_21_R4/IrisChunkGenerator.java
@@ -8,12 +8,17 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
 import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
@@ -26,38 +31,48 @@ 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.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+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.BoundingBox;
 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.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R4.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R4.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R4.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 import org.spigotmc.SpigotWorldConfig;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
-import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+import java.lang.reflect.Method;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -174,8 +189,61 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager, ResourceKey<Level> resourcekey) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager, resourcekey);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager, ResourceKey<Level> levelKey) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.lookupOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.get(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    holder,
+                    levelKey,
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    biome -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -208,11 +276,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -220,7 +283,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
    }

    @Override
@@ -230,22 +293,70 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, vanilla);
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
    }

    @Override
-    public int getFirstFreeHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstFreeHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
    }

-    @Override
-    public int getFirstOccupiedHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstOccupiedHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
-    @Override
-    public void addVanillaDecorations(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinY() + 1;
+        int maxY = heightAccessor.getMaxY();
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -263,9 +374,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        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) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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
@@ -294,7 +418,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_21_R4/src/main/java/com/volmit/iris/core/nms/v1_21_R4/NMSBinding.java
+++ b/nms/v1_21_R4/src/main/java/com/volmit/iris/core/nms/v1_21_R4/NMSBinding.java
@@ -2,12 +2,16 @@ package com.volmit.iris.core.nms.v1_21_R4;

 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.agent.Agent;
 import com.volmit.iris.util.collection.KList;
@@ -61,6 +65,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -93,6 +99,7 @@ import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;

 public class NMSBinding implements INMSBinding {
    private final KMap<Biome, Object> baseBiomeCache = new KMap<>();
@@ -734,6 +741,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().lookupOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().lookupOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::get)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(Pair::getA, Pair::getB, (a, b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");
--- a/nms/v1_21_R5/src/main/java/com/volmit/iris/core/nms/v1_21_R5/IrisChunkGenerator.java
+++ b/nms/v1_21_R5/src/main/java/com/volmit/iris/core/nms/v1_21_R5/IrisChunkGenerator.java
@@ -8,12 +8,17 @@ import com.volmit.iris.engine.framework.ResultLocator;
 import com.volmit.iris.engine.framework.WrongEngineBroException;
 import com.volmit.iris.engine.object.IrisJigsawStructure;
 import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
+import com.volmit.iris.engine.object.IrisStructurePopulator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
 import com.volmit.iris.util.mantle.flag.MantleFlag;
 import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.reflect.WrappedField;
+import com.volmit.iris.util.reflect.WrappedReturningMethod;
+import net.minecraft.CrashReport;
+import net.minecraft.CrashReportCategory;
+import net.minecraft.ReportedException;
 import net.minecraft.core.*;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
@@ -26,38 +31,48 @@ 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.levelgen.Heightmap;
-import net.minecraft.world.level.levelgen.RandomState;
+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.BoundingBox;
 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.templatesystem.StructureTemplateManager;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R5.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R5.generator.CustomChunkGenerator;
+import org.bukkit.craftbukkit.v1_21_R5.generator.structure.CraftStructure;
+import org.bukkit.event.world.AsyncStructureSpawnEvent;
 import org.spigotmc.SpigotWorldConfig;

 import javax.annotation.Nullable;
 import java.lang.reflect.Field;
-import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+import java.lang.reflect.Method;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;

 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 KMap<ResourceKey<Structure>, KSet<String>> structures = new KMap<>();
+    private final IrisStructurePopulator populator;

    public IrisChunkGenerator(ChunkGenerator delegate, long seed, Engine engine, World world) {
        super(((CraftWorld) world).getHandle(), edit(delegate, new CustomBiomeSource(seed, engine, world)), null);
        this.delegate = delegate;
        this.engine = engine;
+        this.populator = new IrisStructurePopulator(engine);
        var dimension = engine.getDimension();

        KSet<IrisJigsawStructure> placements = new KSet<>();
@@ -174,8 +189,61 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
    }

    @Override
-    public void createStructures(RegistryAccess iregistrycustom, ChunkGeneratorStructureState chunkgeneratorstructurestate, StructureManager structuremanager, ChunkAccess ichunkaccess, StructureTemplateManager structuretemplatemanager, ResourceKey<Level> resourcekey) {
-        delegate.createStructures(iregistrycustom, chunkgeneratorstructurestate, structuremanager, ichunkaccess, structuretemplatemanager, resourcekey);
+    public void createStructures(RegistryAccess registryAccess, ChunkGeneratorStructureState structureState, StructureManager structureManager, ChunkAccess access, StructureTemplateManager templateManager, ResourceKey<Level> levelKey) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+        var chunkPos = access.getPos();
+        var sectionPos = SectionPos.bottomOf(access);
+        var registry = registryAccess.lookupOrThrow(Registries.STRUCTURE);
+        populator.populateStructures(chunkPos.x, chunkPos.z, (key, ignoreBiomes) -> {
+            var loc = ResourceLocation.tryParse(key);
+            if (loc == null) return false;
+            var holder = registry.get(loc).orElse(null);
+            if (holder == null) return false;
+            var structure = holder.value();
+            var biomes = structure.biomes();
+
+            var start = structure.generate(
+                    holder,
+                    levelKey,
+                    registryAccess,
+                    this,
+                    biomeSource,
+                    structureState.randomState(),
+                    templateManager,
+                    structureState.getLevelSeed(),
+                    chunkPos,
+                    fetchReferences(structureManager, access, sectionPos, structure),
+                    access,
+                    biome -> ignoreBiomes || biomes.contains(biome)
+            );
+
+            if (!start.isValid())
+                return false;
+
+            BoundingBox box = start.getBoundingBox();
+            AsyncStructureSpawnEvent event = new AsyncStructureSpawnEvent(
+                    structureManager.level.getMinecraftWorld().getWorld(),
+                    CraftStructure.minecraftToBukkit(structure),
+                    new org.bukkit.util.BoundingBox(
+                            box.minX(),
+                            box.minY(),
+                            box.minZ(),
+                            box.maxX(),
+                            box.maxY(),
+                            box.maxZ()
+                    ), chunkPos.x, chunkPos.z);
+            Bukkit.getPluginManager().callEvent(event);
+            if (!event.isCancelled()) {
+                structureManager.setStartForStructure(sectionPos, structure, start, access);
+            }
+            return true;
+        });
+    }
+
+    private static int fetchReferences(StructureManager structureManager, ChunkAccess access, SectionPos sectionPos, Structure structure) {
+        StructureStart structurestart = structureManager.getStartForStructure(sectionPos, structure, access);
+        return structurestart != null ? structurestart.getReferences() : 0;
    }

    @Override
@@ -208,11 +276,6 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        return delegate.fillFromNoise(blender, randomstate, structuremanager, ichunkaccess);
    }

-    @Override
-    public int getBaseHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getBaseHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
    @Override
    public WeightedList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
@@ -220,7 +283,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager);
+        applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, true);
    }

    @Override
@@ -230,22 +293,70 @@ public class IrisChunkGenerator extends CustomChunkGenerator {

    @Override
    public void applyBiomeDecoration(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager, boolean vanilla) {
-        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, vanilla);
+        addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+        delegate.applyBiomeDecoration(generatoraccessseed, ichunkaccess, structuremanager, false);
    }

    @Override
-    public int getFirstFreeHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstFreeHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
+    public void addVanillaDecorations(WorldGenLevel level, ChunkAccess chunkAccess, StructureManager structureManager) {
+        if (!structureManager.shouldGenerateStructures())
+            return;
+
+        SectionPos sectionPos = SectionPos.of(chunkAccess.getPos(), level.getMinSectionY());
+        BlockPos blockPos = sectionPos.origin();
+        WorldgenRandom random = new WorldgenRandom(new XoroshiroRandomSource(RandomSupport.generateUniqueSeed()));
+        long i = random.setDecorationSeed(level.getSeed(), blockPos.getX(), blockPos.getZ());
+        var structures = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        var list = structures.stream()
+                .sorted(Comparator.comparingInt(s -> s.step().ordinal()))
+                .toList();
+
+        var surface = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.WORLD_SURFACE_WG);
+        var ocean = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.OCEAN_FLOOR_WG);
+        var motion = chunkAccess.getOrCreateHeightmapUnprimed(Heightmap.Types.MOTION_BLOCKING);
+        var 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 noAir = engine.getHeight(wX, wZ, false) + engine.getMinHeight() + 1;
+                int noFluid = engine.getHeight(wX, wZ, true) + engine.getMinHeight() + 1;
+                SET_HEIGHT.invoke(ocean, x, z, Math.min(noFluid, ocean.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(surface, x, z, Math.min(noAir, surface.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motion, x, z, Math.min(noAir, motion.getFirstAvailable(x, z)));
+                SET_HEIGHT.invoke(motionNoLeaves, x, z, Math.min(noAir, motionNoLeaves.getFirstAvailable(x, z)));
+            }
+        }
+
+        for (int j = 0; j < list.size(); j++) {
+            Structure structure = list.get(j);
+            random.setFeatureSeed(i, j, structure.step().ordinal());
+            Supplier<String> supplier = () -> structures.getResourceKey(structure).map(Object::toString).orElseGet(structure::toString);
+
+            try {
+                level.setCurrentlyGenerating(supplier);
+                structureManager.startsForStructure(sectionPos, structure).forEach((start) -> start.placeInChunk(level, structureManager, this, random, getWritableArea(chunkAccess), chunkAccess.getPos()));
+            } catch (Exception exception) {
+                CrashReport crashReport = CrashReport.forThrowable(exception, "Feature placement");
+                CrashReportCategory category = crashReport.addCategory("Feature");
+                category.setDetail("Description", supplier::get);
+                throw new ReportedException(crashReport);
+            }
+        }
+
+        Heightmap.primeHeightmaps(chunkAccess, ChunkStatus.FINAL_HEIGHTMAPS);
    }

-    @Override
-    public int getFirstOccupiedHeight(int i, int j, Heightmap.Types heightmap_type, LevelHeightAccessor levelheightaccessor, RandomState randomstate) {
-        return delegate.getFirstOccupiedHeight(i, j, heightmap_type, levelheightaccessor, randomstate);
-    }
-
-    @Override
-    public void addVanillaDecorations(WorldGenLevel generatoraccessseed, ChunkAccess ichunkaccess, StructureManager structuremanager) {
-        delegate.addVanillaDecorations(generatoraccessseed, ichunkaccess, structuremanager);
+    private static BoundingBox getWritableArea(ChunkAccess ichunkaccess) {
+        ChunkPos chunkPos = ichunkaccess.getPos();
+        int minX = chunkPos.getMinBlockX();
+        int minZ = chunkPos.getMinBlockZ();
+        LevelHeightAccessor heightAccessor = ichunkaccess.getHeightAccessorForGeneration();
+        int minY = heightAccessor.getMinY() + 1;
+        int maxY = heightAccessor.getMaxY();
+        return new BoundingBox(minX, minY, minZ, minX + 15, maxY, minZ + 15);
    }

    @Override
@@ -263,9 +374,22 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        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) {
-        return delegate.getBaseColumn(i, j, levelheightaccessor, 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
@@ -294,7 +418,21 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
        }
        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) {
--- a/nms/v1_21_R5/src/main/java/com/volmit/iris/core/nms/v1_21_R5/NMSBinding.java
+++ b/nms/v1_21_R5/src/main/java/com/volmit/iris/core/nms/v1_21_R5/NMSBinding.java
@@ -2,12 +2,16 @@ package com.volmit.iris.core.nms.v1_21_R5;

 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.link.Identifier;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
+import com.volmit.iris.core.nms.container.StructurePlacement;
 import com.volmit.iris.core.nms.container.BlockProperty;
 import com.volmit.iris.core.nms.datapack.DataVersion;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisJigsawStructurePlacement;
 import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.agent.Agent;
 import com.volmit.iris.util.collection.KList;
@@ -60,6 +64,8 @@ import net.minecraft.world.level.dimension.LevelStem;
 import net.minecraft.world.level.levelgen.FlatLevelSource;
 import net.minecraft.world.level.levelgen.flat.FlatLayerInfo;
 import net.minecraft.world.level.levelgen.flat.FlatLevelGeneratorSettings;
+import net.minecraft.world.level.levelgen.structure.placement.ConcentricRingsStructurePlacement;
+import net.minecraft.world.level.levelgen.structure.placement.RandomSpreadStructurePlacement;
 import net.minecraft.world.level.storage.LevelStorageSource;
 import net.minecraft.world.level.storage.PrimaryLevelData;
 import org.bukkit.*;
@@ -92,6 +98,7 @@ import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;

 public class NMSBinding implements INMSBinding {
    private final KMap<Biome, Object> baseBiomeCache = new KMap<>();
@@ -733,6 +740,71 @@ public class NMSBinding implements INMSBinding {
        return new BlockProperty(property.getName(), property.getValueClass(), state.getValue(property), property.getPossibleValues(), property::getName);
    }

+    @Override
+    public void placeStructures(Chunk chunk) {
+        var craft = ((CraftChunk) chunk);
+        var level = craft.getCraftWorld().getHandle();
+        var access = ((CraftChunk) chunk).getHandle(ChunkStatus.FULL);
+        level.getChunkSource().getGenerator().applyBiomeDecoration(level, access, level.structureManager());
+    }
+
+    @Override
+    public KMap<Identifier, StructurePlacement> collectStructures() {
+        var structureSets = registry().lookupOrThrow(Registries.STRUCTURE_SET);
+        var structurePlacements = registry().lookupOrThrow(Registries.STRUCTURE_PLACEMENT);
+        return structureSets.keySet()
+                .stream()
+                .map(structureSets::get)
+                .filter(Optional::isPresent)
+                .map(Optional::get)
+                .map(holder -> {
+                    var set = holder.value();
+                    var placement = set.placement();
+                    var key = holder.key().location();
+                    StructurePlacement.StructurePlacementBuilder<?, ?> builder;
+                    if (placement instanceof RandomSpreadStructurePlacement random) {
+                        builder = StructurePlacement.RandomSpread.builder()
+                                .separation(random.separation())
+                                .spacing(random.spacing())
+                                .spreadType(switch (random.spreadType()) {
+                                    case LINEAR -> IrisJigsawStructurePlacement.SpreadType.LINEAR;
+                                    case TRIANGULAR -> IrisJigsawStructurePlacement.SpreadType.TRIANGULAR;
+                                });
+                    } else if (placement instanceof ConcentricRingsStructurePlacement rings) {
+                        builder = StructurePlacement.ConcentricRings.builder()
+                                .distance(rings.distance())
+                                .spread(rings.spread())
+                                .count(rings.count());
+                    } else {
+                        Iris.warn("Unsupported structure placement for set " + key + " with type " + structurePlacements.getKey(placement.type()));
+                        return null;
+                    }
+
+                    return new Pair<>(new Identifier(key.getNamespace(), key.getPath()), builder
+                            .salt(placement.salt)
+                            .frequency(placement.frequency)
+                            .structures(set.structures()
+                                    .stream()
+                                    .map(entry -> new StructurePlacement.Structure(
+                                            entry.weight(),
+                                            entry.structure()
+                                                    .unwrapKey()
+                                                    .map(ResourceKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .orElse(null),
+                                            entry.structure().tags()
+                                                    .map(TagKey::location)
+                                                    .map(ResourceLocation::toString)
+                                                    .toList()
+                                    ))
+                                    .filter(StructurePlacement.Structure::isValid)
+                                    .toList())
+                            .build());
+                })
+                .filter(Objects::nonNull)
+                .collect(Collectors.toMap(Pair::getA, Pair::getB, (a, b) -> a, KMap::new));
+    }
+
    public LevelStem levelStem(RegistryAccess access, ChunkGenerator raw) {
        if (!(raw instanceof PlatformChunkGenerator gen))
            throw new IllegalStateException("Generator is not platform chunk generator!");