Beleuchtungsberechnungseinheit und Verfahren für dreidimensionalen Graphikbeschleuniger

摘要

A lighting unit which exhibits improved handling of incoming color values corresponding to a polygon. The lighting unit includes an input buffer for storing a plurality of color values, a mode register including a color mode field specifying whether the plurality of color values corresponds to the front or back side of the polygon. Furthermore, the lighting unit includes a register file for storing color information. The register file includes a first and second plurality of registers for storing front and back side color information, respectively. Still further, the lighting unit includes input/output logic configured to perform a transfer color instruction, which first comprises accessing the mode register to obtain a value of the color mode field, and then transferring the plurality of color values from the input buffer to one or more registers within the register file. The one or more registers are located within the first plurality of registers if the value of the color mode field indicates that the plurality of color values correspond to front side color information, and are located within the second plurality of registers if the value of the color mode field indicates back side color information. The one or more registers are located within the first and second plurality of registers if the value of the color mode field indicates both front and back side color information. Finally, the lighting unit includes a lighting computation unit configured to determine a face direction of the polygon. The lighting unit is further configured to use one or more of the plurality of color values (selected in accordance with the face direction) to perform lighting calculations for the polygon.