[Xquartz-dev] glx and multi-sampling

[Ben Byer]

On Feb 5, 2008, at 4:12 PM, Luc Bourhis wrote:

> Hi,
>
> running glxinfo with the latest version (2.1.2), it turns out that  
> glx is at version 1.2, that GLX_ARB_multisample is available on the  
> both of the server and the client side but that multi-sampling is  
> actuall off:
>
> Visual ID: 27  depth=24  class=TrueColor
>    bufferSize=32 level=0 renderType=rgba doubleBuffer=0 stereo=0
>    rgba: redSize=8 greenSize=8 blueSize=8 alphaSize=8
>    auxBuffers=0 depthSize=16 stencilSize=8
>    accum: redSize=16 greenSize=16 blueSize=16 alphaSize=16
>    multiSample=0  multiSampleBuffers=0
>    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>    visualCaveat=None

FWIW, there is a known "issue" with the visuals, in that the list is  
incomplete.  Specifically, consider the following code:

http://cgit.freedesktop.org/xorg/xserver/tree/GL/apple/indirect.c#n929

/* count num configs:
941	        2 stereo (on, off) (optional)
942	        2 Z buffer (0, 24 bit)
943	        2 AUX buffer (0, 2)
944	        2 buffers (single, double)
945	        2 stencil (0, 8 bit)
946	        2 accum (0, 64 bit)
947	        = 64 configs with stereo, or 32 without */

This code is trying to create a list of all of the possible visuals by  
permuting all of the different possible features.  Not only does this  
not take into account what features are actually available to Quartz  
on the hardware, it also doesn't cover all features (like  
multisampling).  This covers the indirect case, but I believe the code  
in the direct case is similar.

What's needed is code that can correctly query the hardware to  
determine its capabilities, and then (intelligently? correctly?)  
generate a list of visuals.

Just thought I'd throw that out there. :)
-b

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