A method and apparatus for performing tessellation lighting operations for
video graphics primitives in a video graphics system is presented. When
the vertex parameters corresponding to the vertices of a video graphics
primitive are received, a tessellation operation is performed such that a
number of component primitives are generated. The vertex parameters
corresponding to the vertices of the component primitives are then
calculated utilizing the vertex parameters for the original video
graphics primitive. Such calculation operations include determining a
corresponding normal vector for each component primitive vertex. Each of
the component primitives is then individually processed. Such processing
may include calculating the lighting effects for each component primitive
and performing additional processing operations that generate pixel
fragments for the primitive. The resulting pixel fragments are blended
with image data stored in a frame buffer, where the image data is used in
generating a displayed image.