Graphics accelerator with improved lighting processor

Abstract

A system and method computes the color of a plurality of vertices of one or more graphic primitives in a graphics accelerator. The method includes the steps of receiving lighting properties of a primitive vertex and determining whether predetermined lighting properties of the vertex are the same as a previously computed vertex. If predetermined lighting properties are the same as the previously computed vertex, then the method retrieves at least one preprocessed value from a storage location; and utilizes the at least one preprocessed value to compute the vertex color. If, however, the predetermined lighting properties are not the same as the previously computed vertex, then the method computes at least one preprocessed value from the received lighting properties of the primitive vertex, stores the at least one computed preprocessed value in a storage location, and utilizes the at least one preprocessed value to compute the vertex color. The system includes at least one processing unit (e.g., ALU) for performing mathematical operations on lighting properties of a vertex of a graphics primitive. It also includes a storage area for storing predetermined values processed by the processing unit. A receiver is included and configured to receive at least two lighting properties defining a primitive vertex, and a lighting property comparator is configured to compare the at least two lighting properties with previously received lighting properties to determine whether they are the same. Finally a controller is provided and adapted to control the storage and retrieval of values from the storage area and the processing unit, the controller including storage control means responsive to the lighting property comparator configured to save newly processed vertex color values in the operational storage register and to retrieve preprocessed values from the storage area.