patch_waterfall.patch

--- src/foliage/waterfall-batcher.ts
+++ src/foliage/waterfall-batcher.ts
@@ -47,6 +47,7 @@
     // Splash Attributes
     private splashOrigin: THREE.InstancedBufferAttribute | null = null;
     private splashVelocity: THREE.InstancedBufferAttribute | null = null; // Stores random velocity params
+    private baseThickness: Float32Array | null = null;

     private constructor() {}

@@ -107,6 +108,7 @@
         this.mesh.instanceMatrix.setUsage(THREE.DynamicDrawUsage);
         this.mesh.count = 0;
         this.mesh.frustumCulled = false;
+        this.baseThickness = new Float32Array(MAX_WATERFALLS);

         // 2. Setup Splash Particles
         // Using 1 triangle for splash drops to save geometry (billboarded in shader)
@@ -265,6 +267,7 @@

         this.idToIndex.set(id, index);
         this.indexToId[index] = id;
+        this.baseThickness![index] = width;

         // 1. Setup Column
         // Cylinder Base: R=1, H=1.
@@ -384,33 +387,17 @@
         if (!this.initialized || !this.idToIndex.has(id)) return;

-        // Note: We need to know the original scale to modify it.
-        // But we didn't store it.
-        // We can get it from matrix.
         const index = this.idToIndex.get(id)!;

         // ⚡ OPTIMIZATION: Bypassed .getMatrixAt() and .decompose() overhead.
-        // Scale is encoded in the lengths of the column vectors of the 4x4 matrix.
         // We need to change the Z scale. We can modify the 3rd column directly.
         const matrixArray = this.mesh!.instanceMatrix.array as Float32Array;
         const offset = index * 16;

-        // Assuming X and Z were equal initially (circular).
-        // Current X scale is the magnitude of the 1st column.
-        const m00 = matrixArray[offset + 0], m01 = matrixArray[offset + 1], m02 = matrixArray[offset + 2];
-        const scaleX = Math.sqrt(m00 * m00 + m01 * m01 + m02 * m02);
-
-        // Current Z scale is the magnitude of the 3rd column.
-        const m20 = matrixArray[offset + 8], m21 = matrixArray[offset + 9], m22 = matrixArray[offset + 10];
-        const currentScaleZ = Math.sqrt(m20 * m20 + m21 * m21 + m22 * m22);
-
-        // Compute target scale
-        const targetScaleZ = scaleX * thicknessScale;
-
-        // Apply scaling factor to the 3rd column
-        if (currentScaleZ > 0.0001) {
-            const ratio = targetScaleZ / currentScaleZ;
-            matrixArray[offset + 8] *= ratio;
-            matrixArray[offset + 9] *= ratio;
-            matrixArray[offset + 10] *= ratio;
-        }
+        // ⚡ OPTIMIZATION: Tracked base thickness in Float32Array to avoid Math.sqrt() overhead.
+        // Since rotation is strictly identity at creation, Z scale corresponds exactly to m22 (offset + 10).
+        const targetScaleZ = this.baseThickness![index] * thicknessScale;
+
+        // Avoid math/ratios and overwrite Z-scale directly.
+        matrixArray[offset + 10] = targetScaleZ;

         this.mesh!.instanceMatrix.needsUpdate = true;