🔦 Path Tracing

Path tracing is a physically based rendering algorithm that estimates global illumination by randomly sampling light paths — sequences of rays bouncing between camera, surfaces and light sources — and averaging thousands of noisy samples into a converged image. Introduced by James Kajiya in 1986 as a Monte Carlo solution to the rendering equation, it naturally reproduces soft shadows, indirect bounce lighting, caustics and depth of field without the ad-hoc tricks rasterization needs. Each frame traces many independent light paths per pixel, following each bounce off a surface with a probability weighted by that surface's bidirectional reflectance distribution function (BRDF), so rough diffuse materials scatter light in many directions while polished mirrors and glass concentrate it into narrow specular reflections and refractions. More samples per pixel reduce noise but cost proportionally more computation, which is why real-time and interactive path tracers — including the Cornell-box-style WebGL2 demo below — lean on denoising filters and progressive, frame-by-frame refinement to look clean and stable well before the image has fully converged to a noise-free result.