High speed Z-buffer with dynamic random access memory
US4679041A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 13, 1985 |
| Grant date | Jul 7, 1987 |
| Priority date | — |
| Expiry date | Jun 13, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T15/405
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The present invention provides apparatus and methods which are most advantageously used in conjunction with a computer display system incorporating the use of a Z-buffer to provide three dimensional hidden surface elimination. A buffer memory is provided which is sufficiently large such that each display element (pixel) on the display is represented by a 16-bit Z value. The Z value corresponds to the Z axis depth of the object at the particular point corresponding to the pixel. The buffer comprises a plurality of dynamic random access memories (D-RAMs) having two operation modes: Normal and Read-Modify-Write (RMW). A counter/pointer register is provided which successively addresses values in the buffer representing successive pixels along scan lines of the display. A graphics processor is provided with coordinates defining a three dimensional image to be displayed and, for each point of the object, computes a current Z.sub.c value beginning at an initial coordinate address in memory. The initial address is loaded into the graphics processor and a D-RAM read-modify write (RMW) cycle is initiated concurrent with the calculation of Z.sub.c. This address corresponds to the address for …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.