OpenGL

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Contents 1 OpenGL Shading Language Reference 1.1 Variable Qualifiers 1.1.1 attribute 1.1.2 uniform 1.1.3 varying 1.2 Built-In Variables 1.3 Variable Types 1.3.1 Scalars (regular C-styled variables) 1.3.2 Vectors 1.3.3 Matrices 1.3.4 Texture Map Readers 1.3.5 Arrays

OpenGL Shading Language Reference

Variable Qualifiers

attribute

frequently changing values from application to vertex shader

uniform

infrequently changing values from application to any shader (vertex or fragment)

varying

interpolated variables from vertex shader to fragment shader

Built-In Variables

If it begins with "gl_" it is a built-in variable. Example is gl_FragColor.

Variable Types

Scalars (regular C-styled variables)

float, int, bool are all supported. Integers are fairly limited and don't behave like they do in C. See orange book, page 66.

Vectors

vec2, vec3, or vec4 (all floating point)

Matrices

mat2, mat3, mat4 (2x2, 3x3, 4x4 matrix respectively)

Texture Map Readers

sampler1D for 1D texture map, sampler2D for 2D texture map, higher dimensions are apparently supported. Samplers cannot be modified by the shader! Samplers are read using the texture lookup functions texture1D, texture2D, etc.

Arrays

Arrays of any type can be created. There are no pointers; to access an array, you must use square brackets. Texture coordinates are accessed via the built-in array declared as: varying vec4 gl_TexCoord[];