Debugging CubeCamera Rendering Issues in Three.js

Based on your description, you're experiencing an issue where textures turn black when updating a CubeCamera, and you've traced it to specific attribute formats (u16_norm for color and f32 for normal) in one of your objects.

Potential Causes

This issue could be related to several factors:

1. Shader Compatibility: The shader snippet you shared uses the color and normal attributes in displacement calculations, which might be causing issues during the cube map rendering pass.

2. Render Target Configuration: Your use of HalfFloatType might be incompatible with certain shader operations or attribute formats.

3. Attribute Format Conflicts: The specific combination of u16_norm and f32 formats might be causing issues during the cube camera rendering pass.

Debugging Steps

Here are some approaches to debug this issue:

1. Check WebGL Errors

Add error checking to see if any WebGL errors are occurring:

JAVASCRIPTCopied
cubeCamera.update(renderer, scene);
console.error(renderer.getContext().getError()); // Check for WebGL errors

2. Isolate the Problematic Object

Try rendering the scene with only the problematic object to confirm it's the source:

JAVASCRIPTCopied
// Store original visibility
const originalVisibility = {};
scene.traverse(obj => {
  if (obj !== problematicObject && obj.visible) {
    originalVisibility[obj.id] = true;
    obj.visible = false;
  }
});

// Test cube camera update
cubeCamera.update(renderer, scene);

// Restore visibility
scene.traverse(obj => {
  if (originalVisibility[obj.id]) {
    obj.visible = true;
  }
});

3. Modify Render Target Settings

Try different render target configurations:

JAVASCRIPTCopied
const renderTarget = new WebGLCubeRenderTarget(dim, { 
  type: HalfFloatType,
  format: RGBAFormat,
  encoding: sRGBEncoding, // Try different encodings
  generateMipmaps: false  // Disable mipmaps to see if that helps
});

4. Simplify the Shader

Create a simplified version of your shader that doesn't use the problematic attributes or operations to confirm the issue:

JAVASCRIPTCopied
// Create a test material without the complex shader operations
const testMaterial = new MeshBasicMaterial({ color: 0xff0000 });
const originalMaterial = problematicObject.material;
problematicObject.material = testMaterial;

// Test cube camera update
cubeCamera.update(renderer, scene);

// Restore original material
problematicObject.material = originalMaterial;

5. Check for Precision Issues

If you're using high-precision calculations in your shader, try adding precision hints:

GLSLCopied
precision highp float;
precision highp int;

6. Renderer Console Output

Enable debug mode in your renderer to get more information:

JAVASCRIPTCopied
renderer.debug.checkShaderErrors = true;

7. Examine Render Targets

Check if the render target is being properly created and used:

JAVASCRIPTCopied
// After cube camera update
console.log('Render target texture valid:', renderTarget.texture !== null);
console.log('Render target texture properties:', {
  format: renderTarget.texture.format,
  type: renderTarget.texture.type,
  encoding: renderTarget.texture.encoding
});

Given that changing attribute formats resolves the issue, you might need to adjust how these attributes are defined or used in your shader. The problem could be related to precision issues or how the CubeCamera's internal rendering process handles these specific attribute formats.