[Paraview] vtkOpenGLProjectedTetrahedraMapper on generic unstructured grid

[Peter Maday]

Dear Paraview users,

I have a .vtk dataset containing an unstructured grid with scalars.
Paraview seems to be able to volume render the dataset (and it
mentions vtkOpenGLProjectedTetrahedraMapper in the progress bar while
doing the rendering). The dataset contains not only tetrahedra, but
other cell types as well.

I would like to do the same volume rendering using VTK only, however
am experiencing some difficulties. The volume rendering mapper gives
an error message stating that only tetrahedral elements are supported
for the rendering. As long as Paraview really relies on
vtkOpenGLProjectedTetrahedraMapper, there has to be a way to modify
the original untructured grid so that the non terahedral cells are
removed / transformed.

My question is if anyone should have some suggestion about how to do
this conversion, or by what means it should be possible to get the
volume rendering working for this kind of dataset.

Thanks a lot,
Peter