Hewlett-packard Company

Hewlett-packard Development Company, L.p.

Ethan W Gannett

Calvin L Selig

Kendall F Tidwell

A method of eliminating stale information from a computer graphics buffer. The method facilitates switching from a fast clear mode to a non fast clear mode during the lifetime of a region of interest such as a window: A clear count value associated with a pixel is read and compared with a current clear count. If the counts are not equal, a replacement value is written into the pixel. The process may be repeated for each pixel in the region. Block transfer hardware and fast clear hardware may be used together to perform the procedure in a high-performance manner: A source region and a destination region for the block transfer operation are both set to the region of interest. As the block transfer proceeds, each pixel is written either with its own value or with a replacement value depending on whether the clear count for the pixel is current.

Technique for eliminating stale information from a computer graphics buffer

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.

Fragment visibility pretest system and methodology for improved

A texture mapping computer graphics system includes a host computer having a system memory that stores texture data. A graphics hardware device, coupled to the host computer, renders texture mapped images, and includes a local memory that stores at least a portion of the texture data stored in the system memory at any one time. A software daemon runs on the processor of the host computer and manages transferring texture data from the system memory to the local memory when needed by the hardware device to render an image. The software daemon monitors use by the hardware device of texture data blocks stored in the local memory. The daemon also tracks the priorities of the texture stored in the main memory so that lowest priority and least recently used texture data blocks in the local memory are replaced with texture data blocks needed by the hardware device to render images.

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Ft. Collins, CO, United States of America

Ethan W Gannett