Update viewer.js

viewer.js

@@ -36,6 +36,15 @@ function hexToRgbaArray(hex) {
   }
 }
 
+
+// ----- Utility: Recursive scene traversal -----
+function traverse(entity, callback) {
+    callback(entity);
+    if (entity.children) {
+        entity.children.forEach(child => traverse(child, callback));
+    }
+}
+
 let pc;
 export let app = null;
 let cameraEntity = null;