A process which stores a representation of a polygon forming a portion of a three-dimensional object and compares the polygon to pixels from a scan line as they are passed by. The processor stores a representation of a polygon and compares each pixel passed by the processor to the polygon to determine whether the pixel is within the polygon. If the pixel is within the polygon, its Z position (depth) is compared to the Z position of a corresponding position in the polygon. If the Z position of the polygon position is in front of the Z position of the pixel so that the polygon would obscure the previous pixel description, the Z position and an associates material value (e.g., color) of the polygon is substituted for the Z position of the pixel. The three-dimensional object is preferably represented with triangles and each polygon processor is preferably a triangle processor, with a series of triangle processors arranged in a pipeline. Two pipelines may be provided in parallel. Several triangle processors can be placed on a single semiconductor chip with input and output buffers for performing multiplexing, delaying and skewing. An X counter on the chip rederives the pixel X position, eliminating the need for this input.