Use child mesh in SplatMesh to auto-inject SparkRenderer instead of monkey-patching (#158)

examples/editor/index.html

@@ -79,6 +79,7 @@
     const canvas = document.getElementById("canvas");
     const renderer = new THREE.WebGLRenderer({ canvas });
     const spark = new SparkRenderer({ renderer });
+    scene.add(spark);
 
     function handleResize() {
       const width = canvas.clientWidth;

examples/envmap/index.html

@@ -61,6 +61,7 @@
 
     // Explicitly create a SparkRenderer to render environment maps
     const spark = new SparkRenderer({ renderer });
+    scene.add(spark);
 
     const splatURL = await getAssetFileURL("fireplace.spz");
     const packedSplats = new PackedSplats({ url: splatURL });

examples/multiple-viewpoints/index.html

@@ -47,6 +47,7 @@
 
     // Explicitly create a SparkRenderer in the scene to spawn new viewpoints
     const spark = new SparkRenderer({ renderer });
+    scene.add(spark);
 
     const splatURL = await getAssetFileURL("butterfly.spz");
     const butterfly = new SplatMesh({ url: splatURL });