[Mesa-dev] [RFC] [PATCH 1/2] mesa: let GL3 buf obj queries not depend on opengl major version

[Ian Romanick]

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On 09/19/2011 10:12 AM, Jose Fonseca wrote:
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>> 
>> On 09/19/2011 07:20 AM, Brian Paul wrote:
>>> On 09/19/2011 04:25 AM, Yuanhan Liu wrote:
>>>> If I understand correctly, the new GL3 buffer object queries 
>>>> parameters, like BUFFER_MAP_ACCESS_FLAGS, depends on 
>>>> ARB_map_buffer_range extension.
>>> 
>>> That would make sense, but in fact the extension spec 
>>> (http://www.opengl.org/registry/specs/ARB/map_buffer_range.txt)
>>>
>>> 
says nothing about these queries.  They were added in GL 3.0.
>> 
>> It seems like this could be an error in the extension spec.  This
>> is one of the extensions, like ARB_framebuffer_object, that "back
>> ports" OpenGL 3.0 functionality to previous versions.  These
>> extensions are supposed to provide *identical* functionality to
>> OpenGL 3.0.  The other cases of mismatches have been determined
>> to be bugs in the extension specs.
> 
> FWIW, this ability would be useful for GL debuggers such as
> apitrace.  Otherwise the ARB_map_buffer_range extension is
> unbalanced: it adds new state that can never be queried.
> 
>> The question is, what do other implementations do?  The other
>> other question is, are there any implementations that support 
>> ARB_map_buffer_range but not OpenGL 3.0?
> 
> Very good questions...
> 
> The answer to the later question can be obtained by data mining
> openbenchmarking.org, by entering this query on google:
> 
> site:openbenchmarking.org GL_ARB_map_buffer_range glxinfo "OpenGL
> version string: 2.1" -mesa
> 
> and there are a few NVIDIA cards / driver combinations out there
> that hit this:
> 
> OpenGL vendor string: NVIDIA Corporation OpenGL renderer string:
> GeForce 7900 GT/GTO/PCI/SSE2 OpenGL version string: 2.1.2 NVIDIA
> 260.19.36

Excellent!  I have a couple Geforce7-class cards at home.  Of course,
I won't be home until next week...

> OpenGL vendor string: NVIDIA Corporation OpenGL renderer string:
> Quadro FX 3450/4000 SDI/PCI/SSE2 OpenGL version string: 2.1.2
> NVIDIA 195.36.31
> 
> OpenGL vendor string: NVIDIA Corporation OpenGL renderer string:
> GeForce Go 7400/PCI/SSE2 OpenGL version string: 2.1.2 NVIDIA
> 270.29
> 
> OpenGL vendor string: NVIDIA Corporation OpenGL renderer string:
> GeForce Go 7900 GS/PCI/SSE2 OpenGL version string: 2.1.2 NVIDIA
> 260.19.06
> 
> OpenGL vendor string: NVIDIA Corporation OpenGL renderer string:
> GeForce 7600 GT/PCI/SSE2 OpenGL version string: 2.1.2 NVIDIA
> 270.30
> 
> If anybody had one of these, we could tell for sure.
> 
> Jose
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