Method and apparatus for controlling compressed Z information in a video graphics system that supports anti-aliasing
US6407741B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 20, 1999 |
| Grant date | Jun 18, 2002 |
| Priority date | — |
| Expiry date | Jul 20, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T9/00
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for managing compressed Z information in a video graphics system that supports anti-aliasing is described. Each pixel in the display frame is represented with a primary Z value, a secondary Z value, a first and second color, and a pixel mask that indicates how the Z values and colors apply to the samples of the pixel. The primary Z values for the pixels in a pixel block are then compressed using a compression algorithm and stored in a Z buffer in a compressed format. A secondary mask that indicates which pixels in the pixel block have valid secondary Z values is also stored in the Z buffer, along with the secondary Z values and the pixel masks in an uncompressed format. A Z mask value for each pixel block in the frame is stored in a Z mask memory, where the Z mask for each pixel block indicates the level of compression of the Z information the corresponding pixel block. When Z information for a pixel block is required for processing operations, a cache is first examined to determine if the Z information for the pixel block is included in the cache. If the Z information is not included in the cache, the Z mask memory is consulted to determine the level of comp…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.