[Paraview] vtkVolumeRayCastSpaceLeapingImageFilter segfault

[Burlen Loring]

Hi,

In 3.12 when volume rendering on image data I'm experiencing segfaults 
in vtkVolumeRayCastSpaceLeapingImageFilter in 
vtkVolumeRayCastSpaceLeapingImageFilterMinMaxExecute. The issue seems to 
be that vtkImageData::ComputeIncrements relies on active scalars being 
set. However, for use with ParaView I don't think this can be 
guaranteed. for instance how would an object that produces multiple 
arrays, eg a reader, correctly set active scalars?

A quick fix is below, the real fix probably is quite a bit more involved.

bug filed http://www.paraview.org/Bug/view.php?id=12842

--- 
ParaView-3.12.0-base/VTK/VolumeRendering/vtkVolumeRayCastSpaceLeapingImageFilter.cxx        
2011-11-08 12:56:45.000000000 -0800
+++ 
ParaView-3.12.0/VTK/VolumeRendering/vtkVolumeRayCastSpaceLeapingImageFilter.cxx     
2012-01-05 16:34:06.217415840 -0800
@@ -801,6 +801,10 @@
      return;
      }

+  // FIXME --- this keeps things running smoothly when active scalars
+  // are not set but modifies the input
+  inData[0][0]->GetPointData()->SetScalars(this->GetCurrentScalars())
+
    const int components = 
this->GetCurrentScalars()->GetNumberOfComponents();
    const unsigned int nComponents = (this->GetIndependentComponents()) 
? components : 1;