Transmission Rendering Issues in Complex Models

Based on the screenshots and your description, you're experiencing a common issue with transmission materials in Three.js when used in more complex scenes. Here are some potential causes and solutions:

Possible Causes

1. Transmission Resolution Scale: The default transmission rendering might not have sufficient resolution for your complex model with thin glass elements.

2. Sorting Issues: In complex models with multiple transparent objects, the rendering order can affect how transmission appears.

3. Material Configuration: The combination of transmission and metallicity might need adjustment for the specific geometry of your glasses.

Solutions to Try

1. Adjust Transmission Resolution Scale

The WebGLRenderer has a property called transmissionResolutionScale that controls the quality of transmission rendering. Try increasing this value:

JAVASCRIPTCopied
renderer.transmissionResolutionScale = 1.5; // Default is 1.0, higher values = better quality

2. Customize Transparent Object Sorting

You might need to customize how transparent objects are sorted:

JAVASCRIPTCopied
renderer.setTransparentSort((a, b) => {
  // Custom sorting logic for your specific scene
  // For example, prioritizing the glasses material
  return a.z - b.z; // Simple depth sorting example
});

3. Material Adjustments

For thin glass elements, try these adjustments:

JAVASCRIPTCopied
// For your glass material
material.transmission = 1.0;
material.metalness = 0.2; // Try reducing from 0.38
material.roughness = 0.0; // Lower roughness for clearer glass
material.ior = 1.5; // Index of refraction for glass
material.thickness = 0.01; // For thin glass elements

4. Ensure Proper Material Configuration

Make sure your material is properly configured for transmission:

JAVASCRIPTCopied
material.transparent = true;
material.depthWrite = false; // Sometimes helps with transmission rendering

Try these adjustments one by one to see which resolves your issue. The transmissionResolutionScale is often the most impactful for improving the quality of transmission rendering in complex scenes.