Programmable Shaders

• Manipulate the light and color using arbitrary user programs
• Applied to either vertices or pixels (also called fragments)
• Applied uniformly to all elements
• Commonly programmed in the following languages: Assembly, Cg, GLSL, HLSL

Vertex Shader

• Manipulates vertex's position, normal, color, or texture coordinate
• Can also access arbitrary data designated by the programmer
• Typically applied before vertices are clipped

Pixel Shader

• Manipulates pixel's color and depth
• Can also access arbitrary data designated by the programmer
• Depending on resolution, an excess of 2 million pixels may need to be rendered, lit, shaded, and colored for each frame

References

• Introduction to GLSL by Marco Benvegnù
• GLSL Orange Book reference site
• NVIDIA Sample Demos