SGI OpenGL Shader™ Level-of-Detail White Paper

Abstract

Current graphics hardware can render objects using simple procedural shaders inreal-time. However, detailed, high-quality shaders will continue to stress the resourcesof hardware for some time to come. Shaders written for film production and softwarerenderers may stretch to thousands of lines. The difficulty of rendering efficiently iscompounded when there is not just one, but a scene full of shaded objects, surpassing thecapability of any hardware to render. This problem has many similarities to therendering of large models, a problem that has inspired extensive research in geometriclevel-of-detail and geometric simplification. We introduce an analogous process forshading, shader simplification. Starting from an initial detailed shader, shadersimplification produces a new shader with extra level-of-detail parameters that controlthe shader execution. The resulting level-of-detail shader, can automatically adjust itsrendered appearance based on measures of distance, size, or importance as well asphysical limits such as rendering time budget or texture usage.