Abstract: A system for implementing polygon edging of objects in a graphics display. In a first pass, the system renders the polygon fill with z-buffer comparison and replace enabled, however, for each pixel written to the display frame buffer and z-buffer, an edging plane bit for the pixel is set. A second pass renders the polygon edges with z-buffer comparison and z-buffer replace enabled and uses the edging plane bit as a virgin bit. A third pass re-renders the polygon fill, but only resets the edging plane bit for each pixel. The system may also use a virgin bit available in the z-buffer as the edging plane bit.