Appeal No. 2005-0342
Application No. 09/758,787
Invention
The invention relates to a lighting processor circuit that efficiently
determines primary and secondary colors in a computer graphics system. See
page 1 of appellant’s specification. Lighting equations using floating point
calculations are used to determine the color values. See page 2 of appellant’s
specification
Claim 1 is representative of the invention and reproduced below:
1. A lighting circuit for use in a graphics adapter of a data
processing system supporting a set of light sources, comprising:
a geometry stage configured to receive the coordinates of a graphic
primitive vertex and the vertex's normal vector and further
configured to:
calculate a first set of floating point values, wherein each of
the first set of values is indicative of the dot product of the
normal vector and a unit vector from the vertex to a
corresponding light source;
calculate a second set of floating point values wherein each
of the second set of values is indicative of the dot product of
the normal vector and a unit half vector, wherein the unit half
vector represents the vector sum of the unit vector from the
vertex to the corresponding light source and the unit vector
from the vertex to an eye point; and
calculate a third set of floating point values wherein each of
the third set of values is indicative of the product of an
attenuation factor associated with each light source and a
spotlight factor associated with each light source, wherein
the attenuation factor decreases as the magnitude of the unit
vector from the vertex to the corresponding light source
increases; and
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Last modified: November 3, 2007