Patent ID: 7158133

Claim:
An apparatus for providing shadow information of a 3D computer graphics object as an output for a graphics computer system, comprising: polygon selection means for selecting a polygon from a plurality of polygons defining the object; rendering information determining means coupled to the polygon selection means for determining rendering information for the polygon in a 3D process; polygon rendering means coupled to the rendering information determining means for rendering the polygon in the 3D process; shadow generation information determining means coupled to the rendering information determining means and the polygon rendering means for determining shadow generation information for pixels of the polygon in the 3D process; a shadow buffer for storing depth values, wherein the shadow generation information determining means uses the depth values to update a previous depth value in a corresponding location stored in the shadow buffer; shading means coupled to the shadow generation information determining means for producing color values in a 2D process using the shadow generation information; a frame buffer for storing attributes of the each pixel; and a memory coupled to the shadow buffer and the frame buffer, the memory including indicator table means for establishing a correspondence between a location of one of the each pixel stored in the frame buffer and the location stored in the shadow buffer.