An Implementation of Quad-fragment Merging for Micropolygon Rendering

Current graphics cards (GPUs) shade small polygons inefficiently. When surfaces are represented using micropolygons of less than a pixel in size, many shading computations performed by a GPU are redundant. Since shading is typically the most expensive operation in a graphics pipeline, this leads to poor rendering performance.
This thesis presents a prototype implementation of quad-fragment merging, which reduces redundant shading work by buffering and selectively merging rasterized fragments prior to shading. The prototype quad-fragment merger is described in detail, and evidence is presented that it is amenable to implementation in fixed-function hardware. Performance results indicate that our implementation decreases shader executions by a factor of eight when rendering micropolygons, and effectively makes use of a number of optimizations to yield high performance. Finally, an early prototype of a corollary technique that shades scenes with motion blur is described, and preliminary results are presented.