Geometric processing stage for a pipelined graphic engine, corresponding method and computer program product therefor

Abstract

A geometric processing stage for a pipelined engine for processing video signals and generating processed video signal in space coordinates (S) adapted for display on a screen. The geometric processing stage includes: a model view module for generating projection coordinates of primitives of the video signals in a view space, said primitives including visible and non-visible primitives, a back face culling module arranged downstream of the model view module for at least partially eliminating the non visible primitives, a projection transform module for transforming the coordinates of the video signals from view space coordinates into normalized projection coordinates (P), and a perspective divide module for transforming the coordinates of the video signals from normalized projection (P) coordinates into screen space coordinates (S). The back face culling module is arranged downstream the projection transform module and operates on normalized projection (P) coordinates of said primitives. The perspective divide module is arranged downstream the back face culling module for transforming the coordinates of the video signals from normalized projection (P) coordinates into screen space coordinates (S). A circuit in the back face culling module can be shared with a standard three dimension back face culling operation when necessary. An application is in graphic engines using standard graphics language like OpenGL and NokiaGL.