Scene management models and overlap tests for tile-based rendering

Abstract

Tile-based rendering (also called chunk rendering or bucket rendering) is a promising technique for low-power, 3D graphics platforms. This technique decomposes a scene into smaller regions called tiles and renders the tiles one-by-one. The advantage of this scheme is that a small memory integrated on the graphics accelerator can be used to store the color components and z values of one tile, so that accesses to the frame and z buffer are local, on-chip accesses which consume significantly less power than off-chip accesses. Tile-based rendering, however, requires that the primitives (commonly triangles) are sorted into bins corresponding to the tiles. This paper describes several algorithms for sorting the primitives into bins and evaluates their computational complexity and memory requirements. In addition, we present and evaluate several tests for determining if a triangle and a tile overlap. Experimental results obtained using several suitable 3D graphics workloads show that various trade-offs can be made and that, usually, better performance can be obtained by trading it for memory. This information allows the designer to select the appropriate method depending on the amount of memory available and the computational power.