Shader Theory - A tutorial on the basics of shading theory in 3D computer graphics. OpenGL Geometry Shader4 Extension - Specification for OpenGL's geometry shader APIs. Geometry shaders live in between vertex and fragment shaders in OpenGL's pipeline, and are used to introduce new primitives based on incoming vertices. Detailed documentation and pipeline diagram. Hardware-Based Nonlinear Filtering and Segmentation - Whitepaper on using high-level shading languages to provide non-linear image filtering. Includes an abstract, diagrams and metacode. Shading Languages for Graphics Hardware - Language-independent overview of 3D shading language pipelines. Describes application to GPU architectures. Wikipedia: Shading Language - Provides an overview and history of various shading languages. Shader Programming - Dr. Jian Huang's presentation on OpenGL shaders; includes history, overview, rendering examples, and comparisons of ARB vs Cg.