1. A method of rendering a visible portion of an image containing a plurality of graphics primitives having a visible common vertex, wherein each primitive has at least two other vertices and edge functions representing lines interconnecting the vertices of each primitive, comprising: forming edge functions for the lines interconnecting the vertices of each primitive using fixed point numbers, wherein the fixed point numbers are either within or on a bounding rectangle that defines the bounds of the fixed point numbers; and rendering the graphics primitives based on the formed edge functions.