It uses the OpenGL color lookup table defined using glPixelMap. Our intent is to eventually abstract lookup table specification to allow multiple lookup tables, but currently we only support one color lookup table at a time. The bumpdiff operator leaves a self-shadowing term in alpha which must be used to modulate the bumpspec result. Two special operators are the assignment and cast operators. Both are used as they typically are in C. Assignment implies a cast to the type of the value being set.
Type conversion is discussed in greater detail in a later section describing type conversion.
An important note about the assignment operator.