Three.js Loading Manager and Asset Caching

Based on the information available in the Three.js documentation, I can help address your questions about asset loading and performance issues in your first-person open-world application.

Asset Caching in Three.js

When you're experiencing freezes on first approach to GLB models despite using LoadingManager for preloading, there are several potential causes:

1. Partial Loading: The LoadingManager only manages the assets that are explicitly loaded through it. If you're using loaders that aren't connected to your manager instance, those assets won't be tracked.

2. Processing vs. Loading: The LoadingManager primarily tracks the download/loading of assets, but not necessarily the processing that happens afterward (like parsing large GLB files or setting up materials).

3. Lazy Loading: Some Three.js components might implement lazy loading strategies where certain processing is deferred until the asset is needed.

Potential Solutions

1. Ensure All Loaders Use Your Manager

Make sure all your loaders (TextureLoader, GLTFLoader, AudioLoader, etc.) are initialized with your LoadingManager:

JAVASCRIPTCopied
const manager = new THREE.LoadingManager();
const textureLoader = new THREE.TextureLoader(manager);
const gltfLoader = new THREE.GLTFLoader(manager);
const audioLoader = new THREE.AudioLoader(manager);

2. Pre-process GLB Models

To address the freeze when approaching models for the first time, you could implement a strategy to pre-process them:

JAVASCRIPTCopied
// During your loading phase
function preProcessModel(gltf) {
    // Force a single frame render of the model
    const tempScene = new THREE.Scene();
    tempScene.add(gltf.scene.clone());
    
    const tempCamera = new THREE.PerspectiveCamera(75, 1, 0.1, 100);
    tempCamera.position.z = 5;
    
    renderer.render(tempScene, tempCamera);
    
    // Clean up
    tempScene.clear();
}

// Use this when loading models
gltfLoader.load('model.glb', (gltf) => {
    preProcessModel(gltf);
    // Continue with your normal handling
    scene.add(gltf.scene);
});

3. Implement Progressive Loading

For large worlds, consider implementing a progressive loading strategy where you:

1. Load low-resolution versions of distant models first
2. Prioritize loading based on player position/direction
3. Use level-of-detail (LOD) techniques

Implementation Recommendations

Based on your specific issue with GLB models causing freezes on first approach:

1. Identify the bottleneck: Use browser performance tools to determine if the freeze is caused by:

   • Shader compilation
   • Geometry processing
   • Texture decoding

2. Pre-compile shaders: If shader compilation is the issue, you can force shader compilation during loading:

JAVASCRIPTCopied
function precompileModelShaders(gltf, renderer) {
    const tempScene = new THREE.Scene();
    tempScene.add(gltf.scene);
    
    // Render from multiple angles to trigger different shader variants
    const tempCamera = new THREE.PerspectiveCamera(75, 1, 0.1, 100);
    const positions = [
        new THREE.Vector3(0, 0, 5),
        new THREE.Vector3(5, 0, 0),
        new THREE.Vector3(0, 5, 0)
    ];
    
    positions.forEach(position => {
        tempCamera.position.copy(position);
        tempCamera.lookAt(0, 0, 0);
        renderer.render(tempScene, tempCamera);
    });
    
    tempScene.clear();
}

3. Implement asset warming: Consider adding a "warming" phase to your loading process where you briefly process each asset before making it available to the main scene.

This approach should help reduce or eliminate the freezes when approaching GLB models for the first time in your application.