Refined terrain assembly

- Ceiling layers use their own thickness generators
- Pack validation accepts independent ceiling layer counts
- Locked strata repeat across the reference height
- Surface and cave palettes share layer emission
- Cave passes release retained chunk sections
- Nested carving preserves outer blend buffers
- Profile blending reuses bounded numeric buffers
- Terrain actuators remove unused state and duplicate checks
- Regression tests cover layers and carving scratch lifetimes

core/src/main/java/art/arcane/iris/core/pack/PackBiomeLayerValidator.java

@@ -22,24 +22,15 @@ import art.arcane.volmlib.util.json.JSONArray;
 import art.arcane.volmlib.util.json.JSONObject;
 
 import java.io.File;
-import java.nio.charset.StandardCharsets;
-import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.List;
 
-/**
- * Validates biome layer stacks. caveCeilingLayers reuses the height generators built from layers,
- * so a biome with more ceiling entries than surface entries has no generator for the extras; the
- * engine skips them, and this validator surfaces the mistake to the author at validate time.
- */
 final class PackBiomeLayerValidator {
-    private static final int DEFAULT_LAYER_COUNT = 1;
-
     private PackBiomeLayerValidator() {
     }
 
-    static List<String> validateCeilingLayerCounts(File biomesFolder) {
+    static List<String> validateLayers(File biomesFolder) {
         List<String> blockingErrors = new ArrayList<>();
         if (biomesFolder == null || !biomesFolder.isDirectory()) {
             return blockingErrors;
@@ -49,24 +40,13 @@ final class PackBiomeLayerValidator {
         biomeFiles.sort(Comparator.comparing(File::getPath));
         for (File biomeFile : biomeFiles) {
             String biomeKey = PackValidationIo.deriveKey(biomesFolder, biomeFile);
-            JSONObject biome;
-            try {
-                biome = new JSONObject(Files.readString(biomeFile.toPath(), StandardCharsets.UTF_8));
-            } catch (Throwable e) {
-                // Invalid JSON is reported by the graph validators; layer counts have nothing to add.
+            JSONObject biome = PackValidationIo.readJson(biomeFile);
+            if (biome == null) {
                 continue;
             }
 
-            Integer layers = arrayLength(biome, "layers", biomeKey, DEFAULT_LAYER_COUNT, blockingErrors);
-            Integer ceiling = arrayLength(biome, "caveCeilingLayers", biomeKey, 0, blockingErrors);
-            if (layers == null || ceiling == null) {
-                continue;
-            }
-
-            if (ceiling > layers) {
-                blockingErrors.add("Biome '" + biomeKey + "' declares " + ceiling + " caveCeilingLayers but only "
-                        + layers + " layers. caveCeilingLayers reuses the layers height generators and must not have more entries.");
-            }
+            validateLayerArray(biome, "layers", biomeKey, blockingErrors);
+            validateLayerArray(biome, "caveCeilingLayers", biomeKey, blockingErrors);
         }
         return blockingErrors;
     }
@@ -126,17 +106,15 @@ final class PackBiomeLayerValidator {
         }
     }
 
-    private static Integer arrayLength(JSONObject biome, String field, String biomeKey, int defaultCount,
+    private static void validateLayerArray(JSONObject biome, String field, String biomeKey,
                                        List<String> blockingErrors) {
         if (!biome.has(field) || biome.isNull(field)) {
-            return defaultCount;
+            return;
         }
 
         JSONArray array = biome.optJSONArray(field);
         if (array == null) {
             blockingErrors.add("Biome '" + biomeKey + "' " + field + " must be an array.");
-            return null;
         }
-        return array.length();
     }
 }

core/src/main/java/art/arcane/iris/core/pack/PackValidator.java

@@ -150,7 +150,7 @@ public final class PackValidator {
                 new File(packFolder, "spawners"), new File(packFolder, "entities")));
         blockingErrors.addAll(PackSpawnValidator.validateCustomBiomeSpawns(
                 new File(packFolder, "biomes"), PackSpawnValidator::resolveEntitySpawnCategory));
-        blockingErrors.addAll(PackBiomeLayerValidator.validateCeilingLayerCounts(new File(packFolder, "biomes")));
+        blockingErrors.addAll(PackBiomeLayerValidator.validateLayers(new File(packFolder, "biomes")));
         blockingErrors.addAll(PackBiomeLayerValidator.validateDecoratorPalettes(
                 new File(packFolder, "biomes"), new File(packFolder, "snippet/decorator")));
         PackStyledRangeDefaultValidator.Validation styledRanges = PackStyledRangeDefaultValidator.validate(packFolder);

core/src/main/java/art/arcane/iris/engine/actuator/IrisBiomeActuator.java

@@ -41,7 +41,6 @@ import art.arcane.volmlib.util.math.RNG;
 import art.arcane.volmlib.util.matter.Matter;
 import art.arcane.volmlib.util.matter.MatterBiomeInject;
 import art.arcane.volmlib.util.matter.slices.BiomeInjectMatter;
-import art.arcane.volmlib.util.scheduling.ChronoLatch;
 import art.arcane.volmlib.util.scheduling.PrecisionStopwatch;
 
 import java.util.List;
@@ -49,7 +48,6 @@ import java.util.Objects;
 
 public class IrisBiomeActuator extends EngineAssignedActuator<PlatformBiome> {
     private final RNG rng;
-    private final ChronoLatch cl = new ChronoLatch(5000);
     private final KMap<String, ResolvedBiome> resolvedBiomes = new KMap<>();
     private final KMap<String, ResolvedBiome> resolvedPhysicalBiomes = new KMap<>();
 

core/src/main/java/art/arcane/iris/engine/actuator/IrisTerrainNormalActuator.java

@@ -46,11 +46,7 @@ import art.arcane.iris.util.common.data.B;
 import lombok.Getter;
 
 public class IrisTerrainNormalActuator extends EngineAssignedActuator<PlatformBlockState> {
-    private static final PlatformBlockState AIR = B.getState("AIR");
     private static final PlatformBlockState BEDROCK = B.getState("BEDROCK");
-    private static final PlatformBlockState LAVA = B.getState("LAVA");
-    private static final PlatformBlockState GLASS = B.getState("GLASS");
-    private static final PlatformBlockState CAVE_AIR = B.getState("CAVE_AIR");
     @Getter
     private final RNG rng;
     @Getter
@@ -83,11 +79,6 @@ public class IrisTerrainNormalActuator extends EngineAssignedActuator<PlatformBl
      */
     @BlockCoordinates
     public void terrainSliver(int x, int z, int xf, Hunk<PlatformBlockState> h, ChunkContext context) {
-        terrainSliverOptimized(x, z, xf, h, context);
-    }
-
-    @BlockCoordinates
-    private void terrainSliverOptimized(int x, int z, int xf, Hunk<PlatformBlockState> h, ChunkContext context) {
         int chunkHeight = h.getHeight();
         int chunkDepth = h.getDepth();
         IrisDimension dimension = getDimension();

core/src/main/java/art/arcane/iris/engine/actuator/IrisTransitionGeometryActuator.java

@@ -42,9 +42,7 @@ public final class IrisTransitionGeometryActuator extends EngineAssignedComponen
             return;
         }
         GeometrySource source = new GeometrySource(blocks, biomes, getEngine().getMinHeight(), context);
-        if (plan != null && plan.hasTransitionAtChunk(x >> 4, z >> 4)) {
-            blendGeometry(x, z, blocks, context, source, plan);
-        }
+        blendGeometry(x, z, blocks, context, source, plan);
     }
 
     public static SavedTerrainChunk capture(int x, int z, Hunk<PlatformBlockState> blocks,

core/src/main/java/art/arcane/iris/engine/mantle/components/CaveCarveScratch.java

@@ -22,6 +22,8 @@ import art.arcane.volmlib.util.matter.Matter;
 import art.arcane.volmlib.util.matter.MatterCavern;
 import art.arcane.volmlib.util.matter.MatterSlice;
 
+import java.util.Arrays;
+
 final class CaveCarveScratch {
     final int[] columnMaxY = new int[256];
     final int[] fluidMaxY = new int[256];
@@ -70,4 +72,9 @@ final class CaveCarveScratch {
     int adaptiveGeometryStep = -1;
     int adaptiveGeometryAxisCells = -1;
     boolean fullWeightsInitialized;
+
+    void releaseSections() {
+        Arrays.fill(sectionMatter, null);
+        Arrays.fill(sectionSlices, null);
+    }
 }

core/src/main/java/art/arcane/iris/engine/mantle/components/IrisCaveCarver3D.java

@@ -436,6 +436,7 @@ public class IrisCaveCarver3D {
 
             return carved;
         } finally {
+            scratchCache.get().releaseSections();
             carving.set(nested);
             if (nested) {
                 scratchCache.set(previousScratch);
@@ -2695,10 +2696,6 @@ public class IrisCaveCarver3D {
         return weight;
     }
 
-    private double signed(double value) {
-        return (value * 2D) - 1D;
-    }
-
     private double applySurfaceCeilingFade(
             CaveCarveScratch scratch,
             double threshold,

core/src/main/java/art/arcane/iris/engine/mantle/components/MantleCarvingComponent.java

@@ -19,6 +19,7 @@
 package art.arcane.iris.engine.mantle.components;
 
 import art.arcane.iris.engine.IrisComplex;
+import art.arcane.iris.engine.framework.Engine;
 import art.arcane.iris.engine.UpperDimensionContext;
 import art.arcane.iris.engine.mantle.MatterGenerationPhase;
 import art.arcane.iris.engine.mantle.ComponentFlag;
@@ -36,7 +37,6 @@ import art.arcane.iris.util.common.data.B;
 import art.arcane.iris.util.project.context.ChunkContext;
 import art.arcane.iris.util.project.stream.ProceduralStream;
 import art.arcane.iris.util.project.stream.utility.ChunkFillableDoubleStream2D;
-import art.arcane.iris.util.simd.SimdKernels;
 import art.arcane.iris.util.simd.SimdSupport;
 import art.arcane.volmlib.util.documentation.ChunkCoordinates;
 import art.arcane.volmlib.util.mantle.flag.ReservedFlag;
@@ -58,6 +58,7 @@ public class MantleCarvingComponent extends IrisMantleComponent {
     private static final double MIN_WEIGHT = 0.08D;
     private static final double THRESHOLD_PENALTY = 0.24D;
     private static final int MAX_BLENDED_PROFILE_PASSES = 2;
+    private static final int MAX_POOLED_WEIGHT_BUFFERS = 64;
     private static final int KERNEL_WIDTH = (BLEND_RADIUS * 2) + 1;
     private static final int KERNEL_SIZE = KERNEL_WIDTH * KERNEL_WIDTH;
     private static final int[] KERNEL_DX = new int[KERNEL_SIZE];
@@ -107,8 +108,25 @@ public class MantleCarvingComponent extends IrisMantleComponent {
         if (!complex.allowsMantleChunkWrite(x, z)) {
             return;
         }
+        BlendScratch previous = BLEND_SCRATCH.get();
+        BlendScratch scratch = previous.inUse ? new BlendScratch() : previous;
+        if (scratch != previous) {
+            BLEND_SCRATCH.set(scratch);
+        }
+        scratch.inUse = true;
+        try {
+            generateLayer(writer, x, z, context, scratch);
+        } finally {
+            scratch.release();
+            if (scratch != previous) {
+                BLEND_SCRATCH.set(previous);
+            }
+        }
+    }
+
+    private void generateLayer(MantleWriter writer, int x, int z, ChunkContext context, BlendScratch blendScratch) {
+        IrisComplex complex = context.getComplex();
         IrisDimensionCarvingResolver.State resolverState = new IrisDimensionCarvingResolver.State();
-        BlendScratch blendScratch = BLEND_SCRATCH.get();
         int[] chunkSurfaceHeights = prepareChunkSurfaceHeights(x, z, context, blendScratch.chunkSurfaceHeights);
         PrecisionStopwatch resolveStopwatch = PrecisionStopwatch.start();
         List<WeightedProfile> weightedProfiles = resolveWeightedProfiles(x, z, complex, resolverState);
@@ -217,12 +235,12 @@ public class MantleCarvingComponent extends IrisMantleComponent {
         BlendScratch blendScratch = BLEND_SCRATCH.get();
         IrisCaveProfile[] profileField = blendScratch.profileField;
         Map<IrisCaveProfile, double[]> columnProfileWeights = blendScratch.columnProfileWeights;
-        IdentityHashMap<IrisCaveProfile, Boolean> activeProfiles = blendScratch.activeProfiles;
         List<IrisCaveProfile> profileOrder = blendScratch.profileOrder;
         IrisCaveProfile[] kernelProfiles = blendScratch.kernelProfiles;
         double[] kernelProfileWeights = blendScratch.kernelProfileWeights;
-        activeProfiles.clear();
+        columnProfileWeights.clear();
         profileOrder.clear();
+        blendScratch.nextWeightBuffer = 0;
         fillProfileField(profileField, chunkX, chunkZ, complex, resolverState, blendScratch);
 
         for (int localX = 0; localX < CHUNK_SIZE; localX++) {
@@ -270,12 +288,8 @@ public class MantleCarvingComponent extends IrisMantleComponent {
 
                     double[] weights = columnProfileWeights.get(profile);
                     if (weights == null) {
-                        weights = new double[CHUNK_AREA];
+                        weights = blendScratch.acquireWeights();
                         columnProfileWeights.put(profile, weights);
-                    } else if (!activeProfiles.containsKey(profile)) {
-                        Arrays.fill(weights, 0D);
-                    }
-                    if (activeProfiles.put(profile, Boolean.TRUE) == null) {
                         profileOrder.add(profile);
                     }
                     weights[columnIndex] = columnWeight;
@@ -316,28 +330,27 @@ public class MantleCarvingComponent extends IrisMantleComponent {
             return weightedProfiles;
         }
 
-        Map<IrisDimensionCarvingEntry, IrisDimensionCarvingEntry[]> dimensionColumnPlans = blendScratch.dimensionColumnPlans;
-        dimensionColumnPlans.clear();
+        Engine engine = getEngineMantle().getEngine();
+        int baseX = PowerOfTwoCoordinates.chunkToBlock(chunkX);
+        int baseZ = PowerOfTwoCoordinates.chunkToBlock(chunkZ);
 
         for (IrisDimensionCarvingEntry entry : entries) {
             if (entry == null || !entry.isEnabled()) {
                 continue;
             }
 
-            IrisBiome rootBiome = IrisDimensionCarvingResolver.resolveEntryBiome(getEngineMantle().getEngine(), entry, resolverState);
+            IrisBiome rootBiome = IrisDimensionCarvingResolver.resolveEntryBiome(engine, entry, resolverState);
             if (rootBiome == null) {
                 continue;
             }
 
-            IrisDimensionCarvingEntry[] columnPlan = dimensionColumnPlans.computeIfAbsent(entry, key -> new IrisDimensionCarvingEntry[CHUNK_AREA]);
-            buildDimensionColumnPlan(columnPlan, chunkX, chunkZ, entry, resolverState);
-
             Map<IrisCaveProfile, double[]> rootProfileColumnWeights = new IdentityHashMap<>();
             List<IrisCaveProfile> rootProfileOrder = new ArrayList<>();
             IrisRange worldYRange = entry.getWorldYRange();
             for (int columnIndex = 0; columnIndex < CHUNK_AREA; columnIndex++) {
-                IrisDimensionCarvingEntry resolvedEntry = columnPlan[columnIndex];
-                IrisBiome resolvedBiome = IrisDimensionCarvingResolver.resolveEntryBiome(getEngineMantle().getEngine(), resolvedEntry, resolverState);
+                IrisDimensionCarvingEntry resolvedEntry = IrisDimensionCarvingResolver.resolveFromRoot(
+                        engine, entry, baseX + (columnIndex >> 4), baseZ + (columnIndex & 15), resolverState);
+                IrisBiome resolvedBiome = IrisDimensionCarvingResolver.resolveEntryBiome(engine, resolvedEntry, resolverState);
                 if (resolvedBiome == null) {
                     continue;
                 }
@@ -349,7 +362,7 @@ public class MantleCarvingComponent extends IrisMantleComponent {
 
                 double[] columnWeights = rootProfileColumnWeights.get(profile);
                 if (columnWeights == null) {
-                    columnWeights = new double[CHUNK_AREA];
+                    columnWeights = blendScratch.acquireWeights();
                     rootProfileColumnWeights.put(profile, columnWeights);
                     rootProfileOrder.add(profile);
                 }
@@ -364,19 +377,6 @@ public class MantleCarvingComponent extends IrisMantleComponent {
         return weightedProfiles;
     }
 
-    private void buildDimensionColumnPlan(IrisDimensionCarvingEntry[] columnPlan, int chunkX, int chunkZ, IrisDimensionCarvingEntry entry, IrisDimensionCarvingResolver.State resolverState) {
-        int baseX = PowerOfTwoCoordinates.chunkToBlock(chunkX);
-        int baseZ = PowerOfTwoCoordinates.chunkToBlock(chunkZ);
-        for (int localX = 0; localX < CHUNK_SIZE; localX++) {
-            int worldX = baseX + localX;
-            for (int localZ = 0; localZ < CHUNK_SIZE; localZ++) {
-                int worldZ = baseZ + localZ;
-                int columnIndex = PowerOfTwoCoordinates.packLocal16(localX, localZ);
-                columnPlan[columnIndex] = IrisDimensionCarvingResolver.resolveFromRoot(getEngineMantle().getEngine(), entry, worldX, worldZ, resolverState);
-            }
-        }
-    }
-
     private void fillProfileField(IrisCaveProfile[] profileField, int chunkX, int chunkZ, IrisComplex complex, IrisDimensionCarvingResolver.State resolverState, BlendScratch blendScratch) {
         int startX = PowerOfTwoCoordinates.chunkToBlock(chunkX) - BLEND_RADIUS;
         int startZ = PowerOfTwoCoordinates.chunkToBlock(chunkZ) - BLEND_RADIUS;
@@ -698,8 +698,7 @@ public class MantleCarvingComponent extends IrisMantleComponent {
         private final IrisCaveProfile[] kernelProfiles = new IrisCaveProfile[KERNEL_SIZE];
         private final double[] kernelProfileWeights = new double[KERNEL_SIZE];
         private final IdentityHashMap<IrisCaveProfile, double[]> columnProfileWeights = new IdentityHashMap<>();
-        private final IdentityHashMap<IrisDimensionCarvingEntry, IrisDimensionCarvingEntry[]> dimensionColumnPlans = new IdentityHashMap<>();
-        private final IdentityHashMap<IrisCaveProfile, Boolean> activeProfiles = new IdentityHashMap<>();
+        private final List<double[]> weightBuffers = new ArrayList<>();
         private final List<IrisCaveProfile> profileOrder = new ArrayList<>();
         private final double[] fieldSurfaceHeights = new double[FIELD_SIZE * FIELD_SIZE];
         private final double[] fieldFluidHeights = new double[FIELD_SIZE * FIELD_SIZE];
@@ -710,5 +709,33 @@ public class MantleCarvingComponent extends IrisMantleComponent {
         private final IrisBiome[] fieldCaveBiomes = new IrisBiome[FIELD_SIZE * FIELD_SIZE];
         private final int[] chunkSurfaceHeights = new int[CHUNK_AREA];
         private final double[] chunkSurfaceHeightSamples = new double[CHUNK_AREA];
+        private int nextWeightBuffer;
+        private boolean inUse;
+
+        private double[] acquireWeights() {
+            if (nextWeightBuffer < weightBuffers.size()) {
+                double[] weights = weightBuffers.get(nextWeightBuffer++);
+                Arrays.fill(weights, 0D);
+                return weights;
+            }
+            double[] weights = new double[CHUNK_AREA];
+            if (weightBuffers.size() < MAX_POOLED_WEIGHT_BUFFERS) {
+                weightBuffers.add(weights);
+                nextWeightBuffer++;
+            }
+            return weights;
+        }
+
+        private void release() {
+            Arrays.fill(profileField, null);
+            Arrays.fill(kernelProfiles, null);
+            Arrays.fill(fieldRegions, null);
+            Arrays.fill(fieldSurfaceBiomes, null);
+            Arrays.fill(fieldCaveBiomes, null);
+            columnProfileWeights.clear();
+            profileOrder.clear();
+            nextWeightBuffer = 0;
+            inUse = false;
+        }
     }
 }

core/src/main/java/art/arcane/iris/engine/object/IrisBiome.java

@@ -92,6 +92,7 @@ public class IrisBiome extends IrisRegistrant implements IRare {
     private final transient AtomicCache<IrisBiome> realCarveBiome = new AtomicCache<>();
     private final transient AtomicCache<KList<IrisBiome>> realChildren = new AtomicCache<>();
     private final transient AtomicCache<KList<CNG>> layerHeightGenerators = new AtomicCache<>();
+    private final transient AtomicCache<KList<CNG>> layerCeilingHeightGenerators = new AtomicCache<>();
     private final transient AtomicCache<KList<CNG>> layerSeaHeightGenerators = new AtomicCache<>();
     private final transient AtomicCache<KList<IrisOreGenerator>> surfaceOreCache = new AtomicCache<>();
     private final transient AtomicCache<KList<IrisOreGenerator>> undergroundOreCache = new AtomicCache<>();

core/src/main/java/art/arcane/iris/engine/object/IrisBiomeLayerGenerator.java

@@ -74,7 +74,7 @@ final class IrisBiomeLayerGenerator {
             IrisBiomePaletteLayer layer = layers.get(i);
             double zoom = layer.getZoom();
             CNG hgen = heightGenerators.get(i);
-            double d = hgen.fit(layer.getMinHeight(), layer.getMaxHeight(), wx / zoom, wz / zoom);
+            int d = hgen.fit(layer.getMinHeight(), layer.getMaxHeight(), wx / zoom, wz / zoom);
 
             IrisSlopeClip sc = layer.getSlopeCondition();
 
@@ -88,17 +88,7 @@ final class IrisBiomeLayerGenerator {
                 continue;
             }
 
-            for (int j = 0; j < d; j++) {
-                if (data.size() >= maxDepth) {
-                    break;
-                }
-
-                try {
-                    data.add(layer.get(random, i + j, (wx + j) / zoom, j, (wz - j) / zoom, rdata));
-                } catch (Throwable e) {
-                    IrisLogging.reportError(e);
-                }
-            }
+            appendLayer(data, layer, i, d, wx, wz, random, maxDepth, rdata);
 
             if (data.size() >= maxDepth) {
                 break;
@@ -132,31 +122,20 @@ final class IrisBiomeLayerGenerator {
             return data;
         }
 
-        KList<CNG> heightGenerators = getLayerHeightGenerators(biome, random, rdata);
-        // Ceiling layers reuse the surface-layer height generators, so entries beyond layers.size() have no generator; skip them.
-        int usableLayers = Math.min(layerCount, heightGenerators.size());
+        KList<CNG> heightGenerators = getHeightGenerators(
+                biome.getLayerCeilingHeightGenerators(), ceilingLayers, 7235, random, rdata);
 
-        for (int i = 0; i < usableLayers; i++) {
+        for (int i = 0; i < layerCount; i++) {
             IrisBiomePaletteLayer layer = ceilingLayers.get(i);
             double zoom = layer.getZoom();
             CNG hgen = heightGenerators.get(i);
-            double d = hgen.fit(layer.getMinHeight(), layer.getMaxHeight(), wx / zoom, wz / zoom);
+            int d = hgen.fit(layer.getMinHeight(), layer.getMaxHeight(), wx / zoom, wz / zoom);
 
             if (d <= 0) {
                 continue;
             }
 
-            for (int j = 0; j < d; j++) {
-                if (data.size() >= maxDepth) {
-                    break;
-                }
-
-                try {
-                    data.add(layer.get(random, i + j, (wx + j) / zoom, j, (wz - j) / zoom, rdata));
-                } catch (Throwable e) {
-                    IrisLogging.reportError(e);
-                }
-            }
+            appendLayer(data, layer, i, d, wx, wz, random, maxDepth, rdata);
 
             if (data.size() >= maxDepth) {
                 break;
@@ -198,7 +177,7 @@ final class IrisBiomeLayerGenerator {
                 IrisBiomePaletteLayer layer = layers.get(i);
                 double zoom = layer.getZoom();
                 CNG hgen = heightGenerators.get(i);
-                double d = hgen.fit(layer.getMinHeight(), layer.getMaxHeight(), wx / zoom, wz / zoom);
+                int d = hgen.fit(layer.getMinHeight(), layer.getMaxHeight(), wx / zoom, wz / zoom);
 
                 IrisSlopeClip sc = layer.getSlopeCondition();
 
@@ -212,13 +191,7 @@ final class IrisBiomeLayerGenerator {
                     continue;
                 }
 
-                for (int j = 0; j < d; j++) {
-                    try {
-                        data.add(layer.get(random, i + j, (wx + j) / zoom, j, (wz - j) / zoom, rdata));
-                    } catch (Throwable e) {
-                        IrisLogging.reportError(e);
-                    }
-                }
+                appendLayer(data, layer, i, d, wx, wz, random, Integer.MAX_VALUE, rdata);
             }
         }
 
@@ -227,9 +200,8 @@ final class IrisBiomeLayerGenerator {
         }
 
         for (int i = 0; i < maxDepth; i++) {
-            int offset = (512 - height) - i;
-            int index = offset % data.size();
-            real.add(data.get(Math.max(index, 0)));
+            long offset = 512L - height - i;
+            real.add(data.get(Math.floorMod(offset, data.size())));
         }
 
         return real;
@@ -264,17 +236,7 @@ final class IrisBiomeLayerGenerator {
                 continue;
             }
 
-            for (int j = 0; j < d; j++) {
-                if (data.size() >= maxDepth) {
-                    break;
-                }
-
-                try {
-                    data.add(layer.get(random, i + j, (wx + j) / zoom, j, (wz - j) / zoom, rdata));
-                } catch (Throwable e) {
-                    IrisLogging.reportError(e);
-                }
-            }
+            appendLayer(data, layer, i, d, wx, wz, random, maxDepth, rdata);
 
             if (data.size() >= maxDepth) {
                 break;
@@ -285,7 +247,16 @@ final class IrisBiomeLayerGenerator {
     }
 
     static KList<CNG> getLayerHeightGenerators(IrisBiome biome, RNG rng, IrisData rdata) {
-        AtomicCache<KList<CNG>> cache = biome.getLayerHeightGenerators();
+        return getHeightGenerators(biome.getLayerHeightGenerators(), biome.getLayers(), 7235, rng, rdata);
+    }
+
+    static KList<CNG> getLayerSeaHeightGenerators(IrisBiome biome, RNG rng, IrisData data) {
+        return getHeightGenerators(biome.getLayerSeaHeightGenerators(), biome.getSeaLayers(), 7735, rng, data);
+    }
+
+    private static KList<CNG> getHeightGenerators(AtomicCache<KList<CNG>> cache,
+                                                  KList<IrisBiomePaletteLayer> layers,
+                                                  int seedOffset, RNG rng, IrisData data) {
         KList<CNG> cached = cache.getIfPresent();
 
         if (cached != null) {
@@ -296,36 +267,28 @@ final class IrisBiomeLayerGenerator {
         {
             KList<CNG> layerHeightGenerators = new KList<>();
 
-            int m = 7235;
+            int m = seedOffset;
 
-            for (IrisBiomePaletteLayer i : biome.getLayers()) {
-                layerHeightGenerators.add(i.getHeightGenerator(rng.nextParallelRNG((m++) * m * m * m), rdata));
+            for (IrisBiomePaletteLayer layer : layers) {
+                layerHeightGenerators.add(layer.getHeightGenerator(rng.nextParallelRNG((m++) * m * m * m), data));
             }
 
             return layerHeightGenerators;
         });
     }
 
-    static KList<CNG> getLayerSeaHeightGenerators(IrisBiome biome, RNG rng, IrisData data) {
-        AtomicCache<KList<CNG>> cache = biome.getLayerSeaHeightGenerators();
-        KList<CNG> cached = cache.getIfPresent();
-
-        if (cached != null) {
-            return cached;
-        }
-
-        return cache.aquire(() ->
-        {
-            KList<CNG> layerSeaHeightGenerators = new KList<>();
-
-            int m = 7735;
-
-            for (IrisBiomePaletteLayer i : biome.getSeaLayers()) {
-                layerSeaHeightGenerators.add(i.getHeightGenerator(rng.nextParallelRNG((m++) * m * m * m), data));
+    private static void appendLayer(KList<PlatformBlockState> blocks, IrisBiomePaletteLayer layer,
+                                    int layerIndex, int thickness, double x, double z,
+                                    RNG random, int maxDepth, IrisData data) {
+        double zoom = layer.getZoom();
+        for (int offset = 0; offset < thickness && blocks.size() < maxDepth; offset++) {
+            try {
+                blocks.add(layer.get(random, layerIndex + offset,
+                        (x + offset) / zoom, offset, (z - offset) / zoom, data));
+            } catch (Throwable error) {
+                IrisLogging.reportError(error);
             }
-
-            return layerSeaHeightGenerators;
-        });
+        }
     }
 
     static PlatformBlockState getSurfaceBlock(IrisBiome biome, int x, int z, RNG rng, IrisData idm) {