[vtkusers] Clipping and vtkGPUVolumeRayCastMapper

[Andreas Bruening]

Hi all,
 
there is a strange behaviour when I put some clipplanes into my volumerendering scene. In my program I perform GPU accelerated volumerendering of medical data using vtkGPUVolumeRaycastMapper. I want to add some clipplanes to see what is inside a volume. It is often that the clipplanes clip wrong. The behaviour is similar to the bug reported here: 
http://www.vtk.org/Bug/view.php?id=12377
The mathematics in my code is correct. Origin and normal vector are set correct. When I change the mapper to vtkFixedPointVolumeRaycastMapper everything works fine. And the wrong clipping occurs when I use vtkInteractorStyleTrackballCamera and also when don’t use vtkInteractorStyleTrackballCamera and calculate the cameraposition by my own. 
Also I figured out that the wrong clipping occurs only when the clipplane normal is not orthogonal and it occurs always when the origin is (0, 0, 0).
Is somebody already working on it or does anyone know a workaround? 
 
Thanks in advance
Andi
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