Whittedstyle

Whittedstyle, or Whitted-style ray tracing, is a deterministic rendering algorithm introduced by Turner Whitted in 1980. It extends basic ray casting by recursively tracing rays to model reflection and transmission, enabling accurate rendering of mirror-like surfaces and transparent materials. Local illumination is typically computed using a shading model such as Phong, with shadow rays used to determine visibility to light sources.

In operation, a ray is cast from the camera into the scene and stops at the first surface intersection. The surface color and material properties determine the local illumination; if the material is reflective, a reflection ray is spawned and traced, and if it is transparent, a refraction ray is spawned as well. Each spawned ray is traced to a limited depth, and its contribution is accumulated. For each light source, a shadow ray is cast to test visibility; if blocked by another object, the light's contribution is omitted.

Whitted-style ray tracing excels at producing sharp, accurate reflections and refractions and crisp shadows. It is deterministic and straightforward to implement but computationally intensive, especially with high recursion depths. It does not, by itself, compute global illumination or soft shadows or caustics; such effects typically require extensions, such as radiosity techniques, photon mapping, or stochastic sampling.

Historically, Whitted-style ray tracing was foundational in computer graphics and influenced many later rendering systems. It remains a baseline technique for teaching ray tracing and for production work where specular phenomena are important, serving as a reference implementation and a practical option for high-fidelity imagery.