[Fix] Gaussian splatting GPU picker exclude inactive parts

packages/dev/core/src/Collisions/gpuPicker.ts

@@ -399,6 +399,10 @@ export class GPUPicker {
                 this._meshUniqueIdToPickerId[mesh.uniqueId] = pickId;
                 nextFreeId++;
 
+                if (!mesh.isPickable || !mesh.isVisible) {
+                    continue;
+                }
+
                 // Create a GaussianSplattingMaterial with picking plugin for GPU picking
                 const gsPickingMaterial = this._createGaussianSplattingPickingMaterial(scene, mesh);
                 const plugin = gsPickingMaterial.pluginManager!.getPlugin<GaussianSplattingGpuPickingMaterialPlugin>("GaussianSplatGpuPicking")!;
@@ -496,6 +500,11 @@ export class GPUPicker {
             const plugin = gsPickingMaterial.pluginManager!.getPlugin<GaussianSplattingGpuPickingMaterialPlugin>("GaussianSplatGpuPicking")!;
             plugin.isCompound = true;
             plugin.partMeshIds = partMeshIds;
+            // Only active (included, visible, and pickable) parts should contribute to the depth buffer.
+            const activeParts = group.partEntries
+                .filter((e) => (e.proxy as AbstractMesh).isPickable && (e.proxy as AbstractMesh).isVisible)
+                .map((e) => (e.proxy as any).partIndex as number);
+            plugin.setPartActive(activeParts);
 
             gsPickingMaterial.onBindObservable.add(() => {
                 this._meshRenderingCount++;

packages/dev/core/src/Materials/GaussianSplatting/gaussianSplattingGpuPickingMaterialPlugin.ts

@@ -21,6 +21,7 @@ export class GaussianSplattingGpuPickingMaterialPlugin extends MaterialPluginBas
     private _pickingColor: [number, number, number] = [0, 0, 0];
     private _isCompound: boolean = false;
     private _partPickingColors: number[] = [];
+    private _partVisibility: number[] = [];
     private _maxPartCount: number;
 
     /**
@@ -82,6 +83,21 @@ export class GaussianSplattingGpuPickingMaterialPlugin extends MaterialPluginBas
         this._partPickingColors = colors;
     }
 
+    /**
+     * Sets which parts are active (pickable) for the compound picking pass.
+     * Parts not in the set are discarded in the shader by overriding partVisibility to 0.
+     * @param activeParts Array of part indices that should be pickable.
+     */
+    public setPartActive(activeParts: number[]): void {
+        const visibility = new Array(this._maxPartCount).fill(0.0);
+        for (const index of activeParts) {
+            if (index >= 0 && index < this._maxPartCount) {
+                visibility[index] = 1.0;
+            }
+        }
+        this._partVisibility = visibility;
+    }
+
     /**
      * @returns the class name
      */
@@ -154,8 +170,10 @@ uniform vec3 pickingColor;
                 `,
                 CUSTOM_FRAGMENT_BEFORE_FRAGCOLOR: `
 #if IS_COMPOUND
+    if (vColor.a < 0.001) discard;
     finalColor = vec4(partPickingColors[int(vPartIndex + 0.5)], 1.0);
 #else
+    if (vColor.a < 0.001) discard;
     finalColor = vec4(pickingColor, 1.0);
 #endif
                 `,
@@ -188,8 +206,10 @@ uniform pickingColor: vec3f;
                 `,
                 CUSTOM_FRAGMENT_BEFORE_FRAGCOLOR: `
 #if IS_COMPOUND
+    if (fragmentInputs.vColor.a < 0.001) { discard; }
     finalColor = vec4f(uniforms.partPickingColors[i32(fragmentInputs.vPartIndex + 0.5)], 1.0);
 #else
+    if (fragmentInputs.vColor.a < 0.001) { discard; }
     finalColor = vec4f(uniforms.pickingColor, 1.0);
 #endif
                 `,
@@ -228,6 +248,9 @@ uniform pickingColor: vec3f;
 
         if (this._isCompound) {
             effect.setArray3("partPickingColors", this._partPickingColors);
+            // default all visible when setPartActive hasn't been called
+            const visibility = this._partVisibility.length > 0 ? this._partVisibility : new Array(this._maxPartCount).fill(1.0);
+            effect.setArray("partVisibility", visibility);
         } else {
             effect.setFloat3("pickingColor", this._pickingColor[0], this._pickingColor[1], this._pickingColor[2]);
         }