5.11. Further Information
Many of the built-in functions described in this chapter are used in example shaders in the remainder of this book. All you need to do is keep reading to see them in action.
Some additional detail on the built-in functions can be found in the The OpenGL Shading Language, Version 1.10, by John Kessenich, Dave Baldwin, and Randi Rost (2004).
Various OpenGL Shading Language built-in functions, including the derivative and filter width functions, were inspired by similar functions in RenderMan. Motivation for some of these functions is discussed in The RenderMan Companion: A Programmer's Guide to Realistic Computer Graphics by Steve Upstill (1990) and Advanced RenderMan: Creating CGI for Motion Pictures by Tony Apodaca and Larry Gritz (1999). For additional details on noise functions, see the papers by Perlin and the references provided at the end of Chapter 15.