Appendix I. Built-In OpenGL Shading Language Variables and Functions
The OpenGL Shading Language, commonly called the “GLSL,” defines a number of variables for matching OpenGL state and large set of convenience functions. This appendix provides a complete list of GLSL built-in variables and functions.
 This appendix is adapted from The OpenGL® Shading Language Specification (Versions 1.30 and 1.40) by John Kessenich.
The OpenGL Shading Language has been updated including deprecating and removing some features.
Version 1.30 of GLSL added numerous new functions and data types, while maintaining complete backward compatibility with previous versions of GLSL. No features were removed through deprecation, although various variables ...