Mastering GUI Programming with Python

Programs and shaders

Despite the name, a shader has nothing to do with shadows or shading; it is simply the name for a unit of code that runs on your GPU. In the previous section, we talked about some stages of the rendering pipeline being user-definable; in fact, some of them must be defined, as most OpenGL implementations do not provide default behavior for certain stages. To define those stages, we need to write a shader.

At a minimum, we need to define two shaders:

• The vertex shader: This shader is the first step of the vertex processing stage. Its main job is to determine the spatial coordinates of each vertex.
• The fragment shader: This is the second-to-last stage of the pipeline, and its only required job is to determine the color ...