192 Chapter 3 Renderers
inverses, and inverse transposes. These also include light and material parameters,
fog parameters, and camera and projector coordinate frame information. The 38
functions mentioned in the previous code block implement setting the registers
for these constants. The current values of the renderer constants are automatically
used.
2. Numerical constants. Direct3D requires you to set various numerical constants
used by the shader programs. OpenGL and the software renderer do not.
3. User-defined constants. When writing shader programs, you can have constants
that you will modify within your own application code. These tend to be related
to the physical model of what you are trying to draw. For example, a refraction
effect requir