| XXX - Not complete yet!!! |
| |
| Name |
| |
| SGIX_occlusion_instrument |
| |
| Name Strings |
| |
| GL_SGIX_occlusion_instrument |
| |
| Version |
| |
| $Date: 1998/04/21 03:53:34 $ $Revision: 1.1 $ |
| |
| Number |
| |
| 151 |
| |
| Dependencies |
| |
| SGIX_intruments is required |
| |
| Overview |
| |
| This extension defines an occlusion instrument that can be used by |
| applications to determine whether a set of fragments are completely |
| occluded (i.e., fail the depth test) by fragments already in the |
| frame buffer. |
| |
| Issues |
| |
| * This extension is named like this so that developers have a better |
| idea of what the extension does instead of being obscured by a |
| device-specific name. The extension encompasses functionality that |
| is exposed by the bali_r_extension, but it does not try to address |
| the different mode of retrieving occlusion information. It's |
| possible that Bali may not be able to support this extension easily. |
| |
| |
| New Procedures and Functions |
| |
| None |
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| New Tokens |
| |
| Accepted by the <cap> parameter of Enable, Disable and IsEnabled: |
| |
| OCCLUSION_INSTRUMENT_SGIX 0x6060 |
| |
| Additions to Chapter 2 of the 1.1 Specification (OpenGL Operation) |
| |
| None. |
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| Additions to Chapter 3 of the 1.1 Specification (Rasterization) |
| |
| None. |
| |
| Additions to Chapter 4 of the 1.1 Specification (Per-Fragment Operations |
| and the Frame Buffer) |
| |
| Added to subsection 4.1.5 (Depth buffer test) at the end of the |
| paragraph which begins "If the depth buffer test fails...": |
| |
| If OCCLUSION_INSTRUMENT_SGIX is enabled and instruments have been |
| started via a call to StartInstrumentSGIX, a flag is maintained |
| of whether fragments pass or fail the depth test. The flag's initial |
| state is TRUE and it is set to FALSE whenever a fragment generated |
| during rasterization passes the depth test. |
| |
| The format of the measured occlusion instrument consists of four |
| words: the occlusion instrument enable enum (OCCLUSION_INSTRUMENT_SGIX); |
| the size of the measurement (4); the result of the measurement; and |
| the marker passed in with either StopInstrumentsSGIX or |
| ReadInstrumentsSGIX. |
| |
| Additions to Chapter 5 of the 1.1 Specification (Special Functions) |
| |
| Additions to Chapter 6 of the 1.1 Specification (State and State Requests) |
| |
| Additions to the GLX Specification |
| |
| |
| Errors |
| |
| New State |
| |
| New Implementation Dependent State |
| |
