BDRF map

BRDF stands for Bidirectional Radiance Distribution Function, a way for describing how a surface reflects light. In game shaders BRDF is usually a rougher approximation, simplified for faster rendering. A BRDF map is a vertical gradient mixed with a horizontal gradient, each controlling how the surface reflects light relative to a different angle: one for the camera, and the other for the main light.

BRDF Shaders
1. Brice Vandemoortele and Cedric Caillaud's BRDF shader for Maya supports a BRDF map. It's also been ported to 3ds Max by Christoph "CrazyButcher" Kubisch. More info in the Polycount thread Free Maya/max cgfx/fx Shader. Update: New version here with many updates, including object-space normal maps, relief mapping, self-shadowing, etc.

2. Kostas "Kodde" Gialitakis' Maya CG shader also supports a BRDF map. More info in the Polycount thread "KoddeShader", a Maya CGFX shader.

3. Laurens "Xoliul" Corijn's 3ds Max viewport shader supports Rim Lighting and other techniques similar to BRDF. More info in the Polycount thread TF2 and TOON realtime viewport shader (3ds max).

4. Till "Rollin" Maginot's TF2 Shader for 3ds Max and Toon/Comic Shader for 3ds Max support various lighting techniques similar to BRDF... litsphere, ramp texture, half-Lambert, etc. More info in the Polycount thread TF2 and TOON realtime viewport shader (3ds max).

More shaders are available on the page.