Method and apparatus for rasterizing in a hierarchical tile order

• Main Authors: Hussain, Zahid S, Millet, Timothy J
• Format: Patent
• Language: English
• Published: 09.05.2006

A method and apparatus for efficiently rasterizing graphics is provided. The method is intended to be used in combination with a frame buffer that provides fast tile-based addressing. Within this environment, frame buffer memory locations are organized into a tile hierarchy. For this hierarchy, smaller low-level tiles combine to form larger mid-level tiles. Mid-level tiles combine to form high-level tiles. The tile hierarchy may be expanded to include more levels, or collapsed to included fewer levels. A graphics primitive is rasterized by selecting an starting vertex. The low-level tile that includes the starting vertex is then rasterized. The remaining low-level tiles that are included in the same mid-level tile as the starting vertex are then rasterized. Rasterization continues with the mid-level tiles that are included in the same high-level tile as the starting vertex. These mid-level tiles are rasterized by rasterizing their component low-level tiles. The rasterization process proceeds bottom-up completing at each lower level before completing at higher levels. In this way, the present invention provides a method for rasterizing graphics primitives that accesses memory tiles in an orderly fashion. This reduces page misses within the frame buffer and enhances graphics performance.