HDR Lighting in Three.js

Three-dimensional scenes in web applications have come a long way, and with frameworks like Three.js, creating immersive 3D experiences has never been more accessible. One crucial aspect of creating realistic 3D scenes is lighting. In this article, we'll explore how to use High Dynamic Range (HDR) lighting in Three.js to achieve stunning, realistic results.

The Power of HDR Lighting

When it comes to lighting 3D scenes, developers have several options:

1. Texture baking
2. Real-time lighting with Three.js (directional, ambient, or point light systems)
3. HDR lighting
4. A combination of these techniques

While each method has its merits, HDR lighting stands out as an excellent solution for achieving both realism and performance. HDR lighting provides accurate illumination and reflections, especially for reflective materials.

What is an HDR Image?

An HDR (High Dynamic Range) image is a panoramic photo captured at different exposure levels. This allows for a wider range of luminosity than standard images, providing more detailed highlights and shadows. In 3D scenes, this translates to more realistic lighting and reflections.

Implementing HDR Lighting in Three.js

Let's look at how to load and connect an HDR image to your Three.js scene:

import { RGBELoader } from 'three/examples/jsm/loaders/RGBELoader.js';

// Load the HDR environment map
new RGBELoader().load('path/to/your/hdr/file.hdr', function(texture) {
  texture.mapping = THREE.EquirectangularReflectionMapping;

  scene.background = texture;
  scene.environment = texture;
});

This code snippet demonstrates how to load an HDR file and set it as both the background and the environment map for your scene.

Using HDR Lighting with React Three Fiber

If you're using React Three Fiber, implementing HDR lighting is even simpler. You can use the Environment component with either a preset or your own HDR file:

import { Canvas } from '@react-three/fiber'
import { Environment } from '@react-three/drei'

function Scene() {
  return (
    <Canvas>
      <Environment preset="sunset" />
      {/* Or use your own HDR: files={['path/to/your/hdr.hdr']} */}
    </Canvas>
  )
}

Best Practices and Tips

To get the most out of HDR lighting in your Three.js scenes, keep these points in mind:

1. Resolution matters: For lighting only, you can use a small HDR (as low as 256x256 pixels). However, if you have metallic materials and care about reflection quality, aim for at least 1024x1024 pixels.

2. HDR vs EXR: Both formats work, but HDR is more widely supported. EXR is newer and theoretically better, but HDR is currently more practical for most use cases.

3. Matching isn't critical: Your HDR doesn't need to exactly match your 3D scene. Focus on finding a color tone that complements your environment.

4. Separate background and environment: You can use the same HDR for both, but it's often better to use a higher resolution JPG or PNG for the background and a smaller HDR for lighting and reflections.

5. Check HDR quality: Not all HDRs found online are true HDR images. A real HDR will retain some brightness even when the exposure is turned down to near-zero. You can verify this in image editing software like Photoshop.

Conclusion

HDR lighting is a powerful technique for creating realistic and performant 3D scenes in Three.js. By following the tips and code examples in this article, you'll be well on your way to crafting stunning, immersive 3D web experiences. Experiment with different HDR images and settings to find the perfect look for your project!