[vtkusers] volume rendering using CPU instead of GPU

[Mark Roden]

Hi David,

Thanks for the pointers.  I had been looking at those tests earlier.
I'm considering porting at least the additive test to java, just to
see if it works.  I have a version of the Medical3 test in java, and
doing so will let me know if I should expect this to work, and if not,
to have a concise piece of code to demonstrate the error in the hopes
it can be fixed.

Mark

On Wed, Jan 5, 2011 at 1:58 PM, David Gobbi <david.gobbi at gmail.com> wrote:
> 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
>>
>