Polygon vertex data is processed in three steps to create a graphics display without hidden lines and without gaps in the displayed lines. The technique permits the processing of triangles rather than polygons having four or more sides. In the first step, the Z values for the display points for the visible...http://www.google.com/patents/US4855938?utm_source=gb-gplus-sharePatent US4855938 - Hidden line removal method with modified depth buffer
