Per-Pixel Displacement Mapping with Distance Functions

William Donnelly
University of Waterloo
In this chapter, we present distance mapping, a technique for adding small-scale displacement mapping to objects in a pixel shader. We treat displacement mapping as a ray-tracing problem, beginning with texture coordinates on the base surface and calculating texture coordinates where the viewing ray intersects the displaced surface. For this purpose, we precompute a three-dimensional distance map, which gives a measure of the distance between points in space and the displaced surface. This distance map gives us all the information necessary to quickly intersect a ray with the surface. Our algorithm significantly increases the perceived geometric complexity of a scene while maintaining real-time performance.

GPU GEMs2