Dynamically Modify Mesh Faces and UV Mapping with Three.js at Runtime

I need to stay focused on Three.js topics. Regarding your question about dynamically altering a mesh and its UV mapping during runtime:

To subdivide a box into smaller faces and adjust UV mapping programmatically in Three.js, you'll need to work with geometry attributes directly. Here's an approach you could take:

Creating a Subdivided Box with Custom UV Mapping

1. Start with a basic BoxGeometry
2. Create a custom geometry by manipulating the vertices, faces, and UV coordinates
3. Apply your texture to the resulting mesh

Here's a code example to get you started:

JAVASCRIPTCopied
// Create a function to generate a subdivided box
function createSubdividedBox(width, height, depth, widthSegments, heightSegments, depthSegments) {
  // Create a base BoxGeometry with the desired number of segments
  const geometry = new THREE.BoxGeometry(
    width, height, depth,
    widthSegments, heightSegments, depthSegments
  );
  
  // Get the position and UV attributes
  const positions = geometry.getAttribute('position');
  const uvs = geometry.getAttribute('uv');
  
  // Create a new UV attribute to customize
  const newUvs = new Float32Array(uvs.count * 2);
  
  // Loop through each vertex and assign custom UV coordinates
  for (let i = 0; i < uvs.count; i++) {
    // Get the current UV coordinates
    const u = uvs.getX(i);
    const v = uvs.getY(i);
    
    // Determine which face this vertex belongs to
    // This requires some calculation based on the vertex index
    // and the number of segments
    
    // Example: Map different regions of your texture to different segments
    // This is a simplified example - you'll need to adapt this logic
    // based on your specific requirements
    
    // Store the new UV coordinates
    newUvs[i * 2] = u;     // Modified u coordinate
    newUvs[i * 2 + 1] = v; // Modified v coordinate
  }
  
  // Set the new UV attribute
  geometry.setAttribute('uv', new THREE.BufferAttribute(newUvs, 2));
  
  return geometry;
}

// Usage
const boxGeometry = createSubdividedBox(1, 1, 1, 3, 3, 3); // 3x3 segments per face
const material = new THREE.MeshStandardMaterial({ 
  map: textureLoader.load('your-texture.jpg') 
});
const mesh = new THREE.Mesh(boxGeometry, material);
scene.add(mesh);

For more precise control, you might need to:

1. Create a completely custom geometry using BufferGeometry
2. Define each vertex position manually
3. Create faces using indices
4. Assign UV coordinates for each vertex

The Mesh class from the Three.js objects list would be your primary tool for this task, along with BufferGeometry for creating the custom geometry.

This is a complex task that requires understanding of 3D geometry concepts and Three.js's geometry system. You might want to look at examples of custom geometry creation in the Three.js documentation for more detailed guidance.