Using Displacement Maps with Three.js

Based on your question about using displacement maps to update mesh geometry, I'll provide guidance on how to approach this in Three.js.

Understanding Displacement Maps

In Three.js, displacement maps affect the position of mesh vertices. Unlike other texture maps that only affect lighting and shading, displacement maps physically alter the mesh's geometry, allowing it to cast shadows and interact with other objects as if it had real geometry.

The displacementMap property in MeshStandardMaterial controls this effect, where:

• Black pixels (value 0) represent no displacement
• White pixels (value 1) represent maximum displacement
• The amount of displacement is controlled by displacementScale (default is 1)

Implementing Displacement in Three.js

Instead of manually updating the geometry with compute shaders, you can use Three.js's built-in displacement mapping:

TYPESCRIPTCopied
import * as THREE from 'three';

function setupDisplacementMap(mesh: THREE.Mesh) {
  // Ensure the mesh has a MeshStandardMaterial
  if (!(mesh.material instanceof THREE.MeshStandardMaterial)) {
    console.error('Mesh must use MeshStandardMaterial for displacement');
    return;
  }

  // Load displacement texture
  const textureLoader = new THREE.TextureLoader();
  const displacementMap = textureLoader.load('path/to/displacement-map.jpg');
  
  // Apply to material
  const material = mesh.material as THREE.MeshStandardMaterial;
  material.displacementMap = displacementMap;
  material.displacementScale = 1.0; // Adjust this value as needed
  
  // Make sure the geometry has enough vertices to show displacement
  // If using a basic geometry like BoxGeometry, you might want to increase its segments
  
  // For best results, the geometry should have UVs
  if (!mesh.geometry.attributes.uv) {
    console.warn('Geometry has no UV coordinates, displacement may not work correctly');
  }
}

Important Considerations

1. Geometry Detail: For displacement to look good, your geometry needs enough vertices. Consider using:

   • Higher segment counts in primitive geometries
   • Subdivision modifiers for complex models

2. UV Mapping: Your geometry must have proper UV coordinates for the displacement map to be applied correctly.

3. Performance: Displacement mapping can be performance-intensive with high-poly meshes.

If you specifically need to implement this with compute shaders for custom behavior, you would need to:

1. Create a compute shader that reads the displacement texture
2. Update the position attribute of your geometry
3. Set the needsUpdate flag on the position attribute

However, for most use cases, the built-in displacement mapping in Three.js should be sufficient.