Steaming prefetching texture cache for level of detail maps in a 3D-graphics engine

摘要

Disclosed is a texture prefetching method for use in a three-dimensional graphics display system in which texture maps of an object are stored in memory for texels at (u,v) memory locations. The method of fetching texels for use in calculating (x,y) display pixel values comprises the steps of: a) identifying in (u,v) space a geometric shape to be displayed in (x,y) space, b) establishing tiles of pixels within the geometric shape for use in accessing texels, c) computing texel addresses at one side of a tile based on current addresses (topuc, topvc) and first and second derivatives of (u,v) as a function of (x) and a first derivative as a function of (y), d) computing texel addresses at an opposing side of the tile based on current addresses (u0,v0) and first and second derivatives of (u,v) as a function of (x) and a first derivative as a function of (y), and e) fetching texel blocks within the tiles as defined by the addresses in steps c) and d). In a preferred embodiment, the geometric shape is a triangle, and a tile comprises a quadrilateral having top and bottom pixel locations for two opposing sides, and step c) and step d) define comers of the quadrilateral in (u,v) space.