[vtk-developers] OpenGL Extension loading with OSMesa?

[Cyrus Harrison]

Thanks Burlen!

This was how I read things, but I wanted to make sure I was not missing 
something.

We are looking into this as well for VisIt, b/c we need to be able to 
use extensions in both the X11 and Mesa case.
Our goal is to work with an off-the-shelf VTK build (even if it doesn't 
include mesa support) and I think we are on the right path to do so.

For this issue, my initial conclusion was if we could register functions 
in the vtkgl:: namespace we could bootstrap a workable solution.
However functions in this namespace did not appear to be exported.

Long term, it would be great if there was a path for both the X11 and 
Mesa logic in vtkOpenGLExtensionManager. That rules out some compile 
time choices. We are fine with a pure runtime solution, but I don't 
think that meets the needs of all VTK users.


-Cyrus

On 04/16/13 09:26, burlen wrote:
> Hi Kathleen,
>
> I need this functionality and am starting to work on it, it won't be 
> ready for vtk 6. I'm curious to see if anyone else is already working 
> on it. Please speak up if so.
>
> I'm just digging in but my understanding is that VTK provides it's own 
> extension wrangler (Utilities/ParseOGLExt) for compile time creation 
> of headers (vtkgl.h), and an extension manager 
> vtkOpenGLExtensionManager for run time api to check the results. 
> However, in the cmake code there is logic such that when X11 is 
> disabled or not present, the extension wrangler/pareser is not run. 
> Also like the previous post mentioned the parser is not aware of 
> OSMesaGetProcAddress, thus at run time the extension manager knows 
> nothing about the extensions os mesa provides. So currently OSMesa 
> without X11 means no extensions are available.
>
> Burlen
>
> On 04/15/2013 02:32 PM, Kathleen S. Biagas wrote:
>> Just wanted to ping the list again, see if anyone has an answer to
>> Cyrus' question?
>>
>> Kathleen
>>
>> On Tue, 2013-03-05 at 14:07 -0800, Cyrus Harrison wrote:
>>> Hi Everyone,
>>>
>>> I have been hunting for quite a bit with no luck - so I am hoping the
>>> experts can give me a ruling here:
>>>
>>> Looking at VTK-6 source from git, I was expecting to find
>>> `OSMesaGetProcAddress' wired into the guts of VTK somewhere to support
>>> OpenGL extensions for the OSMesa case.
>>>
>>> Does that logic exist or does OSMesa simply result in a configuration
>>> that defines "VTK_NO_EXTENSION_LOADING"?
>>>
>>>
>>> Thanks for your help,
>>> -Cyrus
>>>
>>>
>>>
>>> _______________________________________________
>>> Powered by www.kitware.com
>>>
>>> Visit other Kitware open-source projects at 
>>> http://www.kitware.com/opensource/opensource.html
>>>
>>> Follow this link to subscribe/unsubscribe:
>>> http://www.vtk.org/mailman/listinfo/vtk-developers
>>>
>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at 
>> http://www.kitware.com/opensource/opensource.html
>>
>> Follow this link to subscribe/unsubscribe:
>> http://www.vtk.org/mailman/listinfo/vtk-developers
>>
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at 
> http://www.kitware.com/opensource/opensource.html
>
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtk-developers
>
>