Displacement mapping by using two passes through the same rasterizer

Abstract

A processing pipeline and method are disclosed that may enable real time video rate displacement mapping. The pipeline may include one or more: render units, texture units, memories, and displacement units. Render units may tessellate a geometric primitive into micropolygons and interpolate parameter values for each new vertex. The micropolygons may be defined by the intersection of the geometric primitive and boundaries projected from specified screen space regions. Texture units retrieve displacement values from a displacement map stored in memory. Displacement units displace each vertex of a micropolygon in the direction of the normal at each vertex by a distance based on the displacement value determined for the vertex location. Micropolygons that are displaced across a projected boundary may be returned to the render units and re-tessellated according to the projected boundaries. Parameter values for new vertices may be determined subject to an edge contract to prevent surface cracks.