Uniform Buffer Binding Issue with MeshStandardMaterial

The error you're encountering with uniform buffer objects (UBOs) when extending a MeshStandardMaterial suggests there's an issue with how the uniform buffer is being defined and bound in your shader modification.

The Problem

The error message indicates that your shader is trying to use a uniform buffer that hasn't been properly bound:

GL_INVALID_OPERATION: It is undefined behaviour to have a used but unbound uniform buffer.

This typically happens when:

1. The uniform buffer is declared in the shader but not properly bound in JavaScript
2. There's a mismatch between how the buffer is defined in the shader and how it's created in JavaScript
3. The binding point (index) for the UBO isn't correctly specified

Potential Solutions

Here are some approaches to fix this issue:

1. Ensure Proper UBO Declaration and Binding

Make sure your globalUBO declaration in the shader includes a binding point that matches how you're creating the uniform buffer:

JAVASCRIPTCopied
// In your shader code (globalUBO)
const globalUBO = `
layout(std140, binding = 0) uniform GlobalUniforms {
    // your uniforms here
};
`;

// When creating the uniform buffer
const globalUniforms = new THREE.UniformsGroup();
// Add your uniforms to globalUniforms
// ...
globalUniforms.setName('GlobalUniforms');
globalUniforms.setBindingPoint(0); // This must match the binding in the shader

2. Check Three.js Version Compatibility

Ensure you're using a recent version of Three.js that fully supports uniform buffer objects. This feature was improved in later versions.

3. Alternative Approach Using Standard Uniforms

If you continue to have issues with UBOs, consider using standard uniforms instead:

JAVASCRIPTCopied
material.onBeforeCompile = (shader) => {
    // Add custom uniforms
    shader.uniforms.myCustomUniform = { value: someValue };
    
    // Modify shader code to use the uniform
    shader.vertexShader = shader.vertexShader.replace(
        '#include <common>',
        `
        uniform float myCustomUniform;
        #include <common>
        `
    );
};

4. Ensure Proper Usage of UniformsGroup

When using UniformsGroup, make sure you're adding uniforms correctly:

JAVASCRIPTCopied
const globalUniforms = new THREE.UniformsGroup();
globalUniforms.setName('GlobalUniforms');
globalUniforms.setBindingPoint(0);

// Add uniforms to the group
globalUniforms.add(new THREE.Uniform('someValue'));

// Then in your material setup
material.onBeforeCompile = (shader) => {
    shader.uniformsGroups = [globalUniforms];
    // Rest of your code...
};

Additional Resources

For more detailed information on working with shaders in Three.js, you might want to explore these components:

• ShaderChunk - for reusable shader code snippets
• ShaderLib - for predefined shader programs
• UniformsLib - for standard uniform collections
• UniformsUtils - for utilities to manage uniforms

These resources can help you better understand how Three.js manages shaders and uniforms internally, which might provide insights into solving your specific issue.