Resolving MMDLoader Shader Compilation Error

Based on your code and the error message "Vertex shader is not compiled" when using MMDLoader in Three.js r171, there are several potential solutions to consider.

Common Causes and Solutions

1. Missing Dependencies: MMDLoader requires additional dependencies to work properly.

2. Shader Initialization: The error suggests that the vertex shader isn't being compiled correctly, which could be related to how the MMDLoader is initialized.

Recommended Solution

Try initializing the MMDLoader with all required dependencies:

JAVASCRIPTCopied
// Import necessary dependencies
import * as THREE from 'three';
import { MMDLoader } from 'three/examples/jsm/loaders/MMDLoader.js';
import { MMDAnimationHelper } from 'three/examples/jsm/animation/MMDAnimationHelper.js';

// Initialize the loader with proper dependencies
const loader = new MMDLoader();
const helper = new MMDAnimationHelper();

// Set up the animation helper
helper.enable('physics', true);
helper.enable('ik', true);

// Load the model
loader.load(
  modelURL,
  (object) => {
    // Add to helper for proper animation and physics
    helper.add(object);
    app.currentMesh = object;
    app.scene.add(app.currentMesh);
  },
  (xhr) => {
    console.log((xhr.loaded / xhr.total) * 100 + "% loaded");
  },
  (error) => {
    console.error("Error loading PMX:", error);
  }
);

Additional Troubleshooting Steps

1. Check WebGL Compatibility: Ensure your browser and hardware support the WebGL features required by the shaders.

2. Verify Model Format: Make sure the model file is valid and compatible with MMDLoader.

3. Check Console for Additional Errors: Look for other error messages that might provide more context.

4. Update Three.js: If possible, try using a different version of Three.js to see if the issue is version-specific.

5. Inspect Shader Code: If you have access to the shader code, check for syntax errors or compatibility issues.

If the issue persists, you might need to examine the specific shader code that's failing to compile, which would require more detailed debugging.