Fragment visibility pretest system and methodology for improved

Abstract

Methods and apparatus for processing graphics information in a computer graphics system for processing graphics information to be rendered on a display screen are provided. The computer graphics system includes a graphics library and graphics hardware together defining a graphics pipeline, and a graphics application program invoking operations in the graphics pipeline through an application program interface provided by the graphics library. The graphics pipeline includes a visibility pretest module, located at a first operational position in the graphics pipeline, configured to determine whether a pixel will be visible or non-visible on the display screen. The pipeline also includes one or more time-intensive modules operationally located at a second position in the graphics pipeline subsequent said first operational position; and a process controller configured to prevent said one or more time-intensive modules from performing operations related to said non-visible pixels. Advantageously, the present invention enables the graphics system to selectively perform graphics pipeline operations which are related to pixels which are ultimately displayed on the display. The processing associated with performing operations on non-displayed pixels is avoided thereby providing the graphics system with significant performance enhancements.