Clipping-ratio-independent 3D graphics clipping engine by dual-thread algorithm

In this paper, we propose a clipping engine (CE) in 3D graphics. A conventional CE shows lower performance as clipping-ratio increases, because the process time of a clipped triangle is much longer than that of a non-clipped triangle. We focus on conserving performance, while clipping-ratio changes. Proposed architecture separates datapath into clip datapath and perspective division & viewport mapping (PDVM) datapath, which makes it possible for CE to handle two triangles at a time. Its performance gain is up to four times of clipping-ratio. It is implemented with 79 k logic gates and 3 kB SRAM in 0.18 um CMOS technology.