Converting GLSL to TSL for Three.js WebGPU

I'll address your questions about converting your GLSL ES 3 shader to TSL for the FreecivX project.

Documentation for TSL

The Three.js Shading Language (TSL) documentation in the Three.js wiki is indeed the primary source for learning TSL. The wiki page you referenced provides the core concepts and syntax for TSL.

Handling 'in' and 'out' Parameters in TSL

In TSL, the input/output system works differently than in GLSL. Instead of using 'in' and 'out' qualifiers:

• Input variables are accessed through predefined variables or uniforms
• The output color in a fragment shader is returned from the main function

For example, if your GLSL has:

GLSLCopied
in vec2 vUv;
out vec4 fragColor;

void main() {
    fragColor = vec4(1.0, 0.0, 0.0, 1.0);
}

In TSL, it would become:

GLSLCopied
varying vec2 vUv;

void main() {
    return vec4(1.0, 0.0, 0.0, 1.0);
}

Initializing the Shader in JavaScript

To initialize a shader using TSL in Three.js:

JAVASCRIPTCopied
import * as THREE from 'three';

const terrainShaderMaterial = new THREE.ShaderMaterial({
  glslVersion: THREE.GLSL3, // Use GLSL3 for WebGPU compatibility
  vertexShader: vertexShaderCode,
  fragmentShader: fragmentShaderCode,
  uniforms: {
    // Your uniforms here
  }
});

Specifying Shader Data (Textures)

To pass textures to your shader:

JAVASCRIPTCopied
// Create a texture
const texture = new THREE.TextureLoader().load('path/to/texture.jpg');

// Create the shader material with the texture as a uniform
const terrainShaderMaterial = new THREE.ShaderMaterial({
  glslVersion: THREE.GLSL3,
  vertexShader: vertexShaderCode,
  fragmentShader: fragmentShaderCode,
  uniforms: {
    terrainTexture: { value: texture },
    // Other uniforms
  }
});

In your shader, you would access it as:

GLSLCopied
uniform sampler2D terrainTexture;

void main() {
    vec4 texColor = texture(terrainTexture, vUv);
    // Use texColor in your shader
    return texColor;
}

Applying the Shader to a Terrain Mesh

Once you have your shader material, you can apply it to your terrain mesh:

JAVASCRIPTCopied
// Create your terrain geometry
const terrainGeometry = new THREE.PlaneGeometry(width, height, segments, segments);

// Create the mesh with your geometry and shader material
const terrainMesh = new THREE.Mesh(terrainGeometry, terrainShaderMaterial);

// Add to your scene
scene.add(terrainMesh);

Using WGSL Directly

While Three.js primarily uses its TSL system for WebGPU, you can use WGSL directly for more advanced cases. The example you referenced (webgpu_compute_texture_pingpong.html) demonstrates using WGSL for compute shaders.

For rendering with WGSL directly, you would need to create a custom material that extends THREE.RawShaderMaterial and provide the WGSL code. However, this is more complex and less documented than using the TSL transpiler.

For your terrain shader, I recommend starting with the TSL approach as it provides better integration with Three.js and handles many WebGPU-specific details for you.

Next Steps

1. Convert your GLSL shader to TSL syntax
2. Set up the ShaderMaterial with appropriate uniforms
3. Test with simple cases first before implementing all features
4. Check the Three.js examples for WebGPU implementations

For more detailed guidance, you might want to explore the Three.js examples directory, particularly the WebGPU examples, which demonstrate various shader techniques with the new rendering backend.