Implement and validate foliage blocker masks across document systems

src/document/scene-document-validation.ts

@@ -3010,6 +3010,64 @@ function validateTerrain(
       }
     }
   }
+
+  const blockerMask = terrain.foliageBlockerMask;
+  const blockerMaskPath = `${path}.foliageBlockerMask`;
+
+  if (blockerMask.resolutionX !== terrain.sampleCountX) {
+    diagnostics.push(
+      createDiagnostic(
+        "error",
+        "invalid-terrain-foliage-blocker-mask-resolution-x",
+        "Terrain foliage blocker mask resolutionX must match terrain sampleCountX.",
+        `${blockerMaskPath}.resolutionX`
+      )
+    );
+  }
+
+  if (blockerMask.resolutionZ !== terrain.sampleCountZ) {
+    diagnostics.push(
+      createDiagnostic(
+        "error",
+        "invalid-terrain-foliage-blocker-mask-resolution-z",
+        "Terrain foliage blocker mask resolutionZ must match terrain sampleCountZ.",
+        `${blockerMaskPath}.resolutionZ`
+      )
+    );
+  }
+
+  const expectedBlockerMaskValueCount =
+    blockerMask.resolutionX * blockerMask.resolutionZ;
+
+  if (blockerMask.values.length !== expectedBlockerMaskValueCount) {
+    diagnostics.push(
+      createDiagnostic(
+        "error",
+        "invalid-terrain-foliage-blocker-mask-value-count",
+        `Terrain foliage blocker mask values must contain exactly ${expectedBlockerMaskValueCount} samples.`,
+        `${blockerMaskPath}.values`
+      )
+    );
+  }
+
+  if (options.terrainSampleValues !== "skip") {
+    for (let index = 0; index < blockerMask.values.length; index += 1) {
+      const maskValue = blockerMask.values[index];
+
+      if (isFiniteNumber(maskValue) && maskValue >= 0 && maskValue <= 1) {
+        continue;
+      }
+
+      diagnostics.push(
+        createDiagnostic(
+          "error",
+          "invalid-terrain-foliage-blocker-mask-value",
+          "Terrain foliage blocker mask values must remain finite values between 0 and 1.",
+          `${blockerMaskPath}.values.${index}`
+        )
+      );
+    }
+  }
 }
 
 function validateFoliagePrototype(

src/document/terrains.ts

@@ -956,7 +956,10 @@ function getStoredTerrainPaintWeightAtSample(
 }
 
 export function getTerrainFoliageMaskSampleIndex(
-  mask: Pick<TerrainFoliageMask | TerrainFoliageBlockerMask, "resolutionX" | "resolutionZ">,
+  mask: Pick<
+    TerrainFoliageMask | TerrainFoliageBlockerMask,
+    "resolutionX" | "resolutionZ"
+  >,
   sampleX: number,
   sampleZ: number
 ): number {
@@ -1096,26 +1099,12 @@ function sampleTerrainFoliageMaskAtGridCoordinate(
   const maxSampleZ = Math.min(mask.resolutionZ - 1, minSampleZ + 1);
   const blendX = clampedSampleX - minSampleX;
   const blendZ = clampedSampleZ - minSampleZ;
-  const value00 = getTerrainFoliageMaskValueAtSample(
+  const readMaskValue = (x: number, z: number) =>
-    mask as TerrainFoliageMask,
+    mask.values[getTerrainFoliageMaskSampleIndex(mask, x, z)] ?? 0;
-    minSampleX,
+  const value00 = readMaskValue(minSampleX, minSampleZ);
-    minSampleZ
+  const value10 = readMaskValue(maxSampleX, minSampleZ);
-  );
+  const value01 = readMaskValue(minSampleX, maxSampleZ);
-  const value10 = getTerrainFoliageMaskValueAtSample(
+  const value11 = readMaskValue(maxSampleX, maxSampleZ);
-    mask as TerrainFoliageMask,
-    maxSampleX,
-    minSampleZ
-  );
-  const value01 = getTerrainFoliageMaskValueAtSample(
-    mask as TerrainFoliageMask,
-    minSampleX,
-    maxSampleZ
-  );
-  const value11 = getTerrainFoliageMaskValueAtSample(
-    mask as TerrainFoliageMask,
-    maxSampleX,
-    maxSampleZ
-  );
 
   return lerp(
     lerp(value00, value10, blendX),

src/foliage/foliage-scatter.ts

@@ -6,6 +6,7 @@ import {
   getTerrainFootprintWidth,
   getTerrainHeightAtSample,
   isTerrainFoliageMaskEmpty,
+  sampleTerrainFoliageBlockerMaskAtWorldPosition,
   sampleTerrainFoliageMaskAtWorldPosition,
   type Terrain
 } from "../document/terrains";
@@ -91,6 +92,7 @@ interface WeightedFoliagePrototypeSet {
 
 export const DEFAULT_FOLIAGE_SCATTER_CHUNK_SIZE_METERS = 16;
 export const DEFAULT_MAX_FOLIAGE_SCATTER_INSTANCES_PER_CHUNK = 512;
+export const FOLIAGE_BLOCKER_MASK_THRESHOLD = 0.1;
 
 const HASH_OFFSET_BASIS = 2166136261;
 const HASH_PRIME = 16777619;
@@ -512,6 +514,18 @@ function generateChunkInstances(options: {
       continue;
     }
 
+    const blockerValue =
+      sampleTerrainFoliageBlockerMaskAtWorldPosition(
+        terrain,
+        worldX,
+        worldZ,
+        false
+      ) ?? 0;
+
+    if (blockerValue > FOLIAGE_BLOCKER_MASK_THRESHOLD) {
+      continue;
+    }
+
     const noiseValue = sampleValueNoise(
       worldX,
       worldZ,

src/viewport-three/viewport-host.ts

@@ -391,6 +391,7 @@ interface ActiveTerrainBrushStroke {
   heightSampleIndices: Set<number>;
   paintWeightIndices: Set<number>;
   foliageMaskValueKeys: Set<string>;
+  foliageBlockerMaskValueIndices: Set<number>;
   referenceHeight: number | null;
   lastAppliedPoint: {
     x: number;
@@ -498,6 +499,8 @@ const TERRAIN_BRUSH_PREVIEW_FLATTEN_COLOR = 0xf1d37d;
 const TERRAIN_BRUSH_PREVIEW_PAINT_COLOR = 0x8eb9ff;
 const TERRAIN_BRUSH_PREVIEW_FOLIAGE_PAINT_COLOR = 0x65d36e;
 const TERRAIN_BRUSH_PREVIEW_FOLIAGE_ERASE_COLOR = 0xf0a853;
+const TERRAIN_BRUSH_PREVIEW_FOLIAGE_BLOCKER_PAINT_COLOR = 0xdf5e77;
+const TERRAIN_BRUSH_PREVIEW_FOLIAGE_BLOCKER_ERASE_COLOR = 0x5ec6df;
 const TERRAIN_BRUSH_PREVIEW_OFFSET = 0.05;
 const BOX_CREATE_PREVIEW_FILL = 0x89b6ff;
 const BOX_CREATE_PREVIEW_EDGE = 0xf3be8f;