[vtkusers] volume rendering using CPU instead of GPU

[David Gobbi]

It looks like I might have been wrong about my last statement.
I see this in vtkVolumeMapper.h:

  SetBlendModeToAdditive();

So it looks like at least some of the VTK volume renderers
can do summation.  It looks like there are even some tests:

VolumeRendering/Testing/Cxx/TestGPURayCastAdditive.cxx
VolumeRendering/Testing/Cxx/TestGPURayCastPerspectiveParallel.cxx

Interesting stuff.

  David


On Wed, Jan 5, 2011 at 2:35 PM, David Gobbi <david.gobbi at gmail.com> wrote:
> About all that I can suggest is that you look directly into the code for
> vtkOpenGLGPUVolumeRayCastMapper::LoadExtensions() and see
> what extension is failing.
>
> In LoadExtensions(), the one place where it can fail without printing
> the extension it failed on is right here:
>
>    if(glslMajor<1 || (glslMajor==1 && glslMinor<20))
>      {
>      this->LoadExtensionsSucceeded=0;
>      }
>
> That might provide you with some clues.
>
> Also, don't forget my earlier comment that VTK volume rendering
> does not do averaging or summation, so if averaging is what you
> need, then all of this is moot :)
>
>  David
>
>
> On Wed, Jan 5, 2011 at 2:11 PM, Mark Roden <mmroden at gmail.com> wrote:
>> Hi David,
>>
>> I'm actually doing this on Windows this time.  Sorry I didn't
>> specify-- although it's good to know to not even try on the mac just
>> yet :)
>>
>> Thanks,
>> Mark
>