[vtkusers] "manually" specify extents for vtkXMLPRectilinearGridWriter

[Crni Gorac]

I have set of values, defined on nodes of 3D rectilinear grid, and
generated by an MPI-enabled program.  I want to write results in
parallel, in multiple pieces, into .pvtr format.  I think I have
everything set up properly, except that
vtkXMLPRectilinearGridWriter::SetStartPiece() and
vtkXMLPRectilinearGridWriter::SetEndPiece() are not really woring for
my case.  Namely, the domain decomposition in my case is such that for
example for 200x200x200 grid, first MPI process is generating 50x50x50
block of values starting from point (0,0,0), then second MPI process
is generating block of same size starting from point (50,0,0), then
third MPI process is generating block starting from point (0,50,0),
etc.  So I'd need to specify these extents somehow "manually", but I'm
not able to find how to do it.  I can create vtkExtentTranslator
object, and then employ vtkExtentTranslator::SetWholeExtent() and
vtkExtentTraslator::SetExtent(), that I guess would do the job for me,
but I don't know how to "attach" this vtkExtentTranslator object to
vtkXMLPRectilinearGridWriter object.

Note that I'm using VTK 5.10, and that I really don't have any sort of
VTK pipeline in place - I'm using VTK just for this output operation
(for the purpose of examining results calculated by my code in
ParaView).

Thanks.