Method and apparatus for controlling compressed Z information in a video graphics system
US6636226B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 2002 |
| Grant date | Oct 21, 2003 |
| Priority date | — |
| Expiry date | Nov 25, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T15/405
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for managing compressed Z information in a video graphics system is described. Pixels in a display frame are grouped into a plurality of pixel blocks, where each pixel block includes a plurality of pixels. When possible, the Z information corresponding to the plurality of pixels in a pixel block is compressed and stored in a Z buffer in a compressed 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 a level of compression of the Z information for each of the pixel blocks. 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 compression of the Z information for the particular pixel block. Based on the indication provided by the Z mask memory as to the level of compression, a predetermined amount of data is retrieved from the Z buffer, and when the Z information is in compressed format, it is decompressed. The fetched Z information is then stored…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.