Division-free rasterizer for perspective-correct texture filtering

Perspective-correct texturing for correct 3D graphics images requires per-pixel division, which can be avoided by midpoint algorithms. Previous approaches using midpoint algorithms for perspective-correct texturing evaluate the integer texture coordinates, which are not suitable for trilinear filtering used in most applications. In this paper, we propose a rasterizer architecture which separates the evaluation of the integer part and the computation of the fraction parts. The fraction part of a texture coordinate is computed per cycle in spite of short pipeline depth, consequently much smaller cost than divider. The implemented parallel rasterizer runs at 100 MHz clock and evaluates 400 M pixels and 800 M texture coordinates per second.