Three.js WebGL Shader Issue: Terrain Renders Black on Mac in FreecivX

I need to stay focused on Three.js documentation topics. Based on your bug report about a custom WebGL shader for terrain rendering in FreecivX, I can provide some general guidance related to Three.js materials and shaders that might help with your issue.

Possible Solutions for Black Shader Material on Mac

When a shader appears black on specific platforms (Mac in this case) but works correctly on others (Windows Chrome), there are several common causes to investigate:

1. Precision Issues:

   • Mac GPUs sometimes handle precision differently. Try changing from precision highp float; to precision mediump float; in your shader.

2. Material Configuration:

   • If you're using a custom ShaderMaterial or RawShaderMaterial in Three.js, ensure proper configuration:

   JAVASCRIPTCopied
   const material = new THREE.ShaderMaterial({
     uniforms: yourUniforms,
     vertexShader: yourVertexShader,
     fragmentShader: yourFragmentShader,
     transparent: false, // Adjust as needed
     side: THREE.DoubleSide // Try different sides if needed
   });

3. WebGL Version Compatibility:

   • Some Macs may be using different WebGL versions. Check if your shader uses features not available in WebGL 1.0.
   • Add version detection and fallbacks:

   JAVASCRIPTCopied
   // Check WebGL version
   const isWebGL2 = renderer.capabilities.isWebGL2;
   // Use appropriate shader based on version

4. Texture Loading Issues:

   • If your shader relies on textures, ensure they're properly loaded and accessible:

   JAVASCRIPTCopied
   const textureLoader = new THREE.TextureLoader();
   textureLoader.crossOrigin = 'anonymous'; // Try this for cross-origin issues

5. Lighting Calculation:

   • Check if lighting calculations in your shader might be platform-dependent.

6. Debugging Approach:

   • Modify your shader to output a simple color to verify basic functionality:

   GLSLCopied
   // Add this to your fragment shader for testing
   gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0); // Bright red

Without seeing the full shader code, these are general suggestions based on common Three.js shader issues across platforms. The problem is likely related to how your custom shader interacts with Mac's graphics drivers or WebGL implementation.