Debugging Performance Issues with GLB Models Containing Lights

When GLB models with lights cause performance issues, there are several approaches you can use to diagnose and resolve the problems.

Performance Debugging Tools

1. Chrome DevTools Performance Panel:

   • Record a performance profile while loading your scene
   • Look for long tasks in the main thread
   • Identify JavaScript execution bottlenecks

2. Stats.js:

   • Add real-time FPS monitoring to your scene:

   JAVASCRIPTCopied
   import Stats from 'three/examples/jsm/libs/stats.module.js';
   
   const stats = new Stats();
   document.body.appendChild(stats.dom);
   
   // In your animation loop
   function animate() {
     requestAnimationFrame(animate);
     stats.begin();
     // render scene
     stats.end();
   }

3. Timer Utility:

   • Use Three.js Timer utility for more detailed performance metrics:

   JAVASCRIPTCopied
   import { Timer } from 'three/examples/jsm/misc/Timer.js';
   
   const timer = new Timer();
   timer.start();
   
   // Later in your code
   console.log(timer.getElapsed());

Common Issues with Lights in GLB Models

1. Shadow Maps: Lights with shadows are computationally expensive. Check if your imported lights have shadows enabled.

2. Light Count: Three.js has performance limitations with multiple lights. WebGL has a limit on the number of lights that can affect a single material.

3. Light Types: Point and spot lights are more expensive than directional lights, especially with shadows.

Solutions to Try

1. Extract and Optimize Lights:

   JAVASCRIPTCopied
   let lightCount = 0;
   
   gltfLoader.load('model.glb', (gltf) => {
     gltf.scene.traverse((child) => {
       // Log any lights found
       if (child.isLight) {
         console.log('Found light in GLB:', child.type, child);
         lightCount++;
         
         // Optionally disable shadows
         child.castShadow = false;
         
         // Or replace with optimized version
         // scene.remove(child);
         // const newLight = new THREE.DirectionalLight(child.color, child.intensity);
         // newLight.position.copy(child.position);
         // scene.add(newLight);
       }
     });
     
     console.log('Total lights found:', lightCount);
     scene.add(gltf.scene);
   });

2. Use BufferGeometryUtils to optimize geometry if your model has complex meshes:

   JAVASCRIPTCopied
   import { BufferGeometryUtils } from 'three/examples/jsm/utils/BufferGeometryUtils.js';
   
   // Merge geometries with the same material
   // This can help if the model has many small parts

3. Disable or Simplify Lights:

   • Consider removing lights from the GLB and adding your own optimized lights
   • Use baked lighting textures instead of real-time lighting when possible

The requestAnimationFrame handler violation warnings typically occur when your render loop takes too long to complete. This is often caused by complex lighting calculations, especially with shadows.

Try these approaches to identify and resolve the specific bottlenecks in your scene.