Hidden contours on a frame-buffer

Abstract

To comply with drafting practices and because shaded images do not always reveal the internal or hiddenstructures of 3D models, designers need wireframe images with hidden lines dashed and nonconlour tesselation edges removed. Software techniques for wireframe rendering of polyhedra that require the viewpoint-dependent identilication of the visible portions of intersection and contour (i.e. silhouette)edges are too slow for interactive applications. Hardware support in contemporary graphics pipelines is unavailable or at best limited to the identification of contour edges. In this paper, new hardware assisted techniques for hidden-line removal and determination of contour edges are presented. The techniques do not require any face/edge adjacency information and can be implemented easily on any platform that supports a hardware z-buffer.