Real-time volumetric lighting with post-processing and raymarching for React Three Fiber and Three.js. Implements god rays, light beams, atmospheric fog, and shadow-casting volumetric effects as custom postprocessing Effects. Use when: (1) Adding volumetric lighting, god rays, or light shafts to a React Three Fiber or Three.js scene, (2) Implementing raymarched light effects as post-processing passes, (3) Creating atmospheric fog or cloud effects with light scattering, (4) Building shadow-mapped volumetric lights with occlusion, (5) Shaping light using SDFs (cone, cylinder, sphere, torus), (6) Setting up multi-light volumetric setups, (7) Optimizing raymarching performance with blue noise dithering, (8) Working with coordinate space transformations between screen space and world space for post-processing effects, (9) Creating custom pmndrs/postprocessing Effect classes with depth buffer access.