2.13.1 Lighting

GL lighting computes a color for each vertex sent to the GL. This is accomplished by applying an equation defined by a client-specified lighting model to a collection of parameters that can include the vertex coordinates, the coordinates of one or more light sources, the current normal, and parameters defining the characteristics of the light sources and a current material. The following discussion assumes that the GL is in RGBA mode. (Color index lighting is described in section 2.13.5.)

Lighting may be in one of two states:

1. Lighting Off. In this state the color assigned to a vertex is the current color.
2. Lighting On. In this state, a vertex's color is found by computing a value given the current lighting parameters.

• Lighting Operation