[vtkusers] vtkUnstructuredGridVolumeRayCastMapper

[Paul McGuinness]

Hi vtk users,

I hope that someone will be able to help me. This is my problem:

I create a vtkUnstructuredGrid and create cells inside this grid by doing
the following:

ugrid->Allocate(num_of_vertices_per_facet, num_of_vertices_per_facet);
  ugrid->Initialize();

for (i=0; i<number_of_facets; i++)
	ugrid->InsertNextCell(VTK_TRIANGLE, num_of_vertices_per_facet,
facet_vertices[i]);

ugrid->SetPoints(points);   //coordinates of vertices
  points->Delete();

ugrid->GetPointData()->SetScalars(scalars); //scalar values at vertices
  scalars->Delete();

OK so that is pretty basic stuff.
But here is the problem I want to create a volume rendering of this grid.
So I just do the following:

vtkPiecewiseFunction *opacityTransferFunction2 = vtkPiecewiseFunction::New();
   opacityTransferFunction2->AddPoint(0.0,   0.1);
  opacityTransferFunction2->AddPoint(5.0,  0.3);
  opacityTransferFunction2->AddPoint(10,  0.6);

  vtkColorTransferFunction *colorTransferFunction2 = vtkColorTransferFunction::New();
  colorTransferFunction2->AddRGBPoint( 0.0, 0.0, 0.0, 0.0);
  colorTransferFunction2->AddRGBPoint( 5, 1.0, 1.0, 1.0);
  colorTransferFunction2->AddRGBPoint( 10, 1, 1, 1);


  vtkVolumeProperty *volumeProperty2 = vtkVolumeProperty::New();
  volumeProperty2->SetColor(colorTransferFunction2);
  volumeProperty2->SetScalarOpacity(opacityTransferFunction2);
  volumeProperty2->SetInterpolationTypeToLinear();

    vtkUnstructuredGridVolumeRayCastMapper *volumeMapper2 = vtkUnstructuredGridVolumeRayCastMapper::New();
        volumeMapper2->SetInput(ugrid);

etc......

When I run my program I get no image, I also get the following warning
message:

Warning: In /cphys/pgrad/mcguinpg/vtk/VTK/Rendering/vtkUnstructuredGridBunykRayCastFunction.cxx, line 583
vtkUnstructuredGridBunykRayCastFunction (0x84cdfb0): Input contains more than tetrahedra - only tetrahedra are supported


Does anyone know what is going on here, I am lost on this one?

Thank you,
Paul.