Feature: Implement wind simulation for foliage rendering across renderer, runtime, and viewport hosts

src/foliage/foliage-instanced-renderer.ts

@@ -473,6 +473,8 @@ export class FoliageInstancedRenderer {
   private scatter: FoliageScatterResult | null = null;
   private prototypeRegistry: FoliagePrototypeRegistry = {};
   private quality: FoliageQualitySettings = resolveFoliageQualitySettings(null);
+  private windTime = 0;
+  private windUniforms: FoliageWindUniformSet[] = [];
   private currentView: FoliageRenderView | null = null;
   private viewSignature: string | null = null;
   private renderResourceSignature: string | null = null;
@@ -498,6 +500,18 @@ export class FoliageInstancedRenderer {
     this.group.userData.nonPickable = true;
   }
 
+  updateWind(deltaSeconds: number) {
+    if (!this.shouldApplyWindShader()) {
+      return;
+    }
+
+    if (Number.isFinite(deltaSeconds) && deltaSeconds > 0) {
+      this.windTime += deltaSeconds;
+    }
+
+    this.writeWindUniforms();
+  }
+
   sync(input: FoliageInstancedRendererSyncInput) {
     const terrains = normalizeTerrainRegistry(input.terrains);
     const quality = resolveFoliageQualitySettings(input.quality);
@@ -536,6 +550,7 @@ export class FoliageInstancedRenderer {
       renderResourceSignature === this.renderResourceSignature &&
       this.scatter !== null
     ) {
+      this.writeWindUniforms();
       this.applyCurrentViewToRenderResources();
       return;
     }
@@ -668,6 +683,7 @@ export class FoliageInstancedRenderer {
     this.currentView = null;
     this.viewSignature = null;
     this.renderResourceSignature = null;
+    this.windUniforms = [];
     this.sourceMeshPromisesByBundledPath.clear();
     this.clearActiveBatches();
   }
@@ -677,6 +693,7 @@ export class FoliageInstancedRenderer {
     this.activeBatchKeyByChunkKey.clear();
     this.activeLodLevelByChunkKey.clear();
     this.renderChunks = [];
+    this.windUniforms = [];
 
     if (this.activeBatchGroup === null) {
       return;
@@ -696,6 +713,41 @@ export class FoliageInstancedRenderer {
     console.warn(message);
   }
 
+  private shouldApplyWindShader(): boolean {
+    return (
+      this.quality.enabled &&
+      this.quality.densityMultiplier > 0 &&
+      this.quality.windEnabled
+    );
+  }
+
+  private registerWindUniforms = (uniforms: FoliageWindUniformSet) => {
+    writeFoliageWindUniformValues(uniforms, this.quality, this.windTime);
+    this.windUniforms.push(uniforms);
+  };
+
+  private writeWindUniforms() {
+    if (!this.shouldApplyWindShader()) {
+      return;
+    }
+
+    for (const uniforms of this.windUniforms) {
+      writeFoliageWindUniformValues(uniforms, this.quality, this.windTime);
+    }
+  }
+
+  private getWindMaterialOptions(): FoliageWindMaterialOptions | undefined {
+    if (!this.shouldApplyWindShader()) {
+      return undefined;
+    }
+
+    return {
+      getSettings: () => this.quality,
+      getTime: () => this.windTime,
+      registerUniforms: this.registerWindUniforms
+    };
+  }
+
   private loadTemplateSourceMeshes(
     bundledPath: string
   ): Promise<FoliageTemplateSourceMesh[]> {
@@ -761,8 +813,12 @@ export class FoliageInstancedRenderer {
       batchGroup.userData.foliageLayerId = batch.layerId;
       batchGroup.userData.foliageTerrainId = batch.terrainId;
 
+      const windOptions = this.getWindMaterialOptions();
+
       for (const sourceMesh of sourceMeshes) {
-        batchGroup.add(createInstancedMeshForSource(batch, sourceMesh));
+        batchGroup.add(
+          createInstancedMeshForSource(batch, sourceMesh, windOptions)
+        );
       }
 
       applyRendererRenderCategoryFromMaterial(batchGroup);

src/runtime-three/runtime-host.ts

@@ -5704,6 +5704,7 @@ export class RuntimeHost {
 
     this.updateTerrainLodVisibility();
     this.foliageRenderer.updateView(this.camera);
+    this.foliageRenderer.updateWind(simulationDt);
     this.updateUnderwaterSceneFog();
     this.syncCelestialShadowState();
 

src/viewport-three/viewport-host.ts

@@ -14188,6 +14188,7 @@ export class ViewportHost {
     this.updateTransformGizmoPose();
     this.updateTerrainLodVisibility();
     this.foliageRenderer.updateView(this.getActiveCamera());
+    this.foliageRenderer.updateWind(dt);
     this.volumeTime += dt;
 
     for (const uniform of this.volumeAnimatedUniforms) {

tests/domain/foliage-render-batches.test.ts

@@ -341,7 +341,11 @@ describe("foliage render batch helpers", () => {
           enabled: false,
           densityMultiplier: 1,
           maxDistanceMultiplier: 1,
-          shadows: "near"
+          shadows: "near",
+          windEnabled: true,
+          windStrength: 1,
+          windSpeed: 1,
+          windDirectionDegrees: 35
         }
       }
     );
@@ -373,7 +377,11 @@ describe("foliage render batch helpers", () => {
           enabled: true,
           densityMultiplier: 1,
           maxDistanceMultiplier: 1,
-          shadows: "near"
+          shadows: "near",
+          windEnabled: true,
+          windStrength: 1,
+          windSpeed: 1,
+          windDirectionDegrees: 35
         }
       }
     );