Spectral Rendering in Three.js

While the provided context doesn't directly address spectral rendering implementation in Three.js, I can offer some guidance based on the available information about Three.js rendering capabilities.

To implement spectral rendering similar to POV-Ray in Three.js, you would likely need to work with custom shaders and potentially leverage the WebGLRenderer's color space handling.

Potential Approach

1. Custom Fragment Shader: Create a shader that can process multiple wavelength-specific grayscale renders.

2. Render Targets: Use multiple render targets to generate the grayscale images for different wavelengths.

3. Color Space Handling: Utilize Three.js's color space capabilities (like the outputColorSpace property of WebGLRenderer) to properly combine the spectral data.

Implementation Outline

JAVASCRIPTCopied
// Create a custom shader material
const spectralMaterial = new THREE.ShaderMaterial({
  uniforms: {
    // Array of textures for different wavelengths
    wavelengthTextures: { value: [] },
    // CIE color matching function data
    cieMatchingFunction: { value: [] }
  },
  vertexShader: /* your vertex shader */,
  fragmentShader: /* your fragment shader that implements spectral combination */
});

// Set up render targets for each wavelength
const renderTargets = [];
for (let i = 0; i < numberOfWavelengths; i++) {
  const renderTarget = new THREE.WebGLRenderTarget(width, height);
  renderTargets.push(renderTarget);
}

// Render each wavelength to its target
wavelengths.forEach((wavelength, index) => {
  // Set material properties for this wavelength
  // ...
  
  // Render to the specific target
  renderer.setRenderTarget(renderTargets[index]);
  renderer.render(scene, camera);
});

// Combine the renders using the spectral material
// ...

// Final render with proper color space
renderer.outputColorSpace = THREE.SRGBColorSpace;
renderer.setRenderTarget(null);
renderer.render(finalScene, camera);

This is a conceptual approach and would require significant customization of shaders to implement the CIE color matching function and properly combine the spectral data.

You might also want to explore the CSS3DRenderer or SVGRenderer if your approach involves compositing multiple renders, though WebGLRenderer would likely be more efficient for this specific use case.