Paving Procedural Roads with Pixel Shaders

Abstract

Modern graphics hardware can be used to create procedural geometry. Our proposal details an optimized method to form roads and similar 3D objects by cookie-cutting them from slightly oversized polygons. The roads follow spline-like curves on a plane. The curves and their offset variants are cast into an approximated, implicit description. This can efficiently be evaluated within a pixel shader to discard pixels that are part of the oversized polygons but not part of the roads. Our method guarantees smooth geometry and smooth texturing. To achieve comparable results with roads formed from polygons in the usual way requires level-of-detail or similar mechanisms which not only complicate development and scene management, but also add load on the CPU.