OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Color and OpenGL

How do we use color in OpenGL? As you’ve seen, it’s the job of the fragment shader to assign a fragment’s color. There are many ways this can be done.

• The fragment shader can generate the fragment’s color without using any “external” data (i.e., data passed into the fragment shader). A very limited example of this was done in our shaders from Chapter 1 where we assigned a constant color to each fragment.

• Additional color data could be provided with each input vertex, potentially modified by another shading stage (e.g., vertex shading), and passed to the fragment shader, which uses that data to determine a color. We’ll demonstrate that in “Vertex Colors” on Page 150 in this chapter.

• Supplemental data—but not specifically ...