A simplified lighting computation applies in color index mode
that uses many of the parameters controlling RGBA lighting,
but none of the RGBA material parameters.
First,
the RGBA diffuse and specular intensities
of light i (
and 
, respectively)
determine
color index diffuse and specular light intensities, 
and
from
and
indicates the R component of the color 
and similarly for 
and 
.
Next, let
where 
and 
are
given by equations 2.4 and 2.5,
respectively,
and 
and 
are given by equations 2.2
and 2.3, respectively.
Let 
.
Finally,
let
Then color index lighting produces a value c, given by
The final color index is
The values 
, 
and 
are material properties
described in Tables 2.7 and 2.8.
Any ambient light intensities are incorporated into 
.
As with RGBA lighting, disabled lights cause the corresponding
terms from the summations to be omitted.
The interpretation of 
and the calculation of front
and back colors is carried out as has already been described
for RGBA lighting.
The values 
, 
, and 
are set with
Material using prop of COLOR_INDEXES.
Their initial values are 0, 1, and 1,
respectively.
The additional state consists of three floating-point values.
These values have no effect on RGBA lighting.