C..2.4 Diffuse Term

The diffuse term needs to take into account whether light falls directly on the vertex, the diffuse color of the light, and the diffuse material property:

$(\max \{l \cdot n, 0\}) \ast \hbox{diffuse}_{light} \ast \hbox{diffuse}_{material}$

where:

$l = (l_{x}, l_{y}, l_{z})$ is the unit vector that points from the vertex to the light position (GL_ POSITION).

$n = (n_{x}, n_{y}, n_{z})$ is the unit normal vector at the vertex.