Transmission Material and Specular Highlights Issue

Based on your description, you're experiencing an issue with specular highlights fading when using transmission materials for transparent ink effects. This is a common challenge when working with transmission materials in Three.js.

Possible Solutions

1. Adjust the transmissionResolutionScale:
   The WebGLRenderer has a property called transmissionResolutionScale that can affect the quality of transmission materials. The default value is 1, but you might want to experiment with different values:

   JAVASCRIPTCopied
   renderer.transmissionResolutionScale = 1.5; // Try increasing this value

   Increasing this value might improve the visual quality of your transmission materials, though it could impact performance.

2. Use emissive properties for highlights:
   Since your specular highlights are fading, you could try using the emissive properties of MeshStandardMaterial to simulate highlights in the transparent areas:

   JAVASCRIPTCopied
   material.emissive.set(0xffffff); // Set to white or another color
   material.emissiveIntensity = 0.5; // Adjust intensity as needed

   If you're using specific areas for highlights, you could use an emissive map:

   JAVASCRIPTCopied
   material.emissiveMap = emissiveTexture;

   Remember that if you use an emissive map, you should set the emissive color to something other than black.

3. Adjust lightMapIntensity:
   If you're using light maps, you could try increasing the light map intensity:

   JAVASCRIPTCopied
   material.lightMapIntensity = 1.5; // Default is 1

These adjustments might help restore the specular highlights in your transparent ink areas while maintaining the transmission effect you're looking for.

I recommend experimenting with these settings to find the right balance for your specific use case.