[vtkusers] Re: Rendering slowed down after recent CVS update

[Francois Bertel]

Hi Paul,

By card upgrade, try a driver upgrade first. http://www.nvidia.com/object/unix.html

You card is listed in the legacy section:
http://www.nvidia.com/object/IO_32667.html

It means you have to deal with the latest legacy driver available for Linux:

http://www.nvidia.com/object/linux_display_x86_96.43.01.html

Once you try this new driver, two cases:

1. it works, just let us know
2. it is still slow, I'll try to make the vtkOpenGLExtensionManager aware of this particular card and of this software fallback. I will need the output of glxinfo:
 $ glxinfo > output.txt

Regards.


Paul Melis wrote:
> Paul Melis wrote:
> 
>> Sean McBride wrote:
>>
>>> /On 1/16/08 4:24 PM, Paul Melis said:
>> />/
>> />>/And another reply to myself...
>> />>/After going back to a CVS version of VTK of October 1st the
>> problem />>/seems to be gone. So something changed in VTK between
>> october and today />>/that influences the render performance, probably
>> due to a software />>/fallback suddenly being used in the NVidia driver.
>> />>/    />>/
>> />/
>> />/Next try Nov 1, Dec 1, etc. until you have it narrowed down to
>> between 2
>> />/days... tedious, but easy.  You'll probably find the problem this way.
>> />/  />/
>> /Well, I made a little script that did all the hard work of checking
>> out a CVS version for specific date, configuring it with cmake,
>> building it, setting appropriate environment variables and then
>> running a little test application. The results indicate that the
>> problems start with commits done on October 27. I suspect the changes
>> relating to alpha handing (for bug 2347) in vtkOpenGLRenderWindow.cxx
>> and friends, although I don't see anything suspicious in the code.
>> Most of the changes seem related to depth peeling and using different
>> blending, but I'm not enabling depth peeling and are also not using
>> any transparent geometry.
>>
>>  
>>
> 
> Okay, further testing shows it is indeed related to using a different
> blending function. If I take the faulty revision and only comment out
> the calls to glBlendFuncSeparate in vtkOpenGLRenderer.cxx and
> vtkOpenGLRenderWindow.cxx the problem goes away, i.e. performance is
> restored. So it looks like a software fallback is used as side-effect of
> this call. Yuck. The card (actually driver) says it's OpenGL 1.5
> capable, and glBlendFuncSeparate was introduced in 1.4. But it doesn't
> seem to be hw-accelerated...
> 
> I guess there's not much of a work-around for this, except a card
> upgrade :-/
> 
> Paul
> 
> 
> _______________________________________________
> This is the private VTK discussion list. Please keep messages on-topic.
> Check the FAQ at: http://www.vtk.org/Wiki/VTK_FAQ
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
> 


-- 
François Bertel, PhD  | Kitware Inc. Suite 204
1 (518) 371 3971 x113 | 28 Corporate Drive
                      | Clifton Park NY 12065, USA