[vtkusers] volume rendering using CPU instead of GPU

[David Gobbi]

Just one additional note.  I just looked at the code for the various
volume mappers, and only the vtkGPUVolumeRayCastMapper
supports the Additive mode.  This mode is not supported by the
vtkVolumeRayCastMapper or vtkFixedPointVolumeRayCastMapper.

I think that I'll play around with this a bit myself when I get home
(since only my home computer supports this GPU stuff).  I'm kind
of curious about how well this Additive mode works.

  David


On Wed, Jan 5, 2011 at 3:40 PM, Mark Roden <mmroden at gmail.com> wrote:
> 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
>>>
>>
>