[Paraview] Explicit numbering of nodes indexes in Xdmf/h5

[Andrew Parker]

All,

I thought I'd forward this onto the paraview lists in case somebody could
think of a way to do this?  Please see my email below which I originally
sent to the vtk user list.  Any help would be very much appreciated,
including the fact that it just cannot be done.  I would in particular
welcome thoughts from those who have helped develop the xdmf2 lib within
the paraview source.

Many thanks again,
Andy

---------- Forwarded message ----------
Date: 23 November 2013 17:13
Subject: [vtkusers] Explicit numbering of nodes for Xdmf/h5
To: "vtkusers at vtk.org" <vtkusers at vtk.org>


All,

In an effort to spark some comments I thought I'd try to provide a small
example for what I want to do in case my previous post (below) was unclear.
 Below is a valid xdmf file that paraview understands for a plane.

<?xml version="1.0"?>
<!DOCTYPE Xdmf SYSTEM "Xdmf.dtd">
<Xdmf xmlns:xi="http://www.w3.org/2003/XInclude" Version="2.2">
  <Domain>
    <Grid GridType="Uniform">
      <Topology TopologyType="Quadrilateral" Dimensions="1">
        <DataItem Dimensions="1 4" NumberType="Int" Precision="8"
Format="XML">
           0 1 3 2
</DataItem>
      </Topology>
      <Geometry GeometryType="XYZ">
        <DataItem Dimensions="4 3" NumberType="Float" Precision="4"
Format="XML">
  -0.5 -0.5 0
  0.5 -0.5 0
  -0.5 0.5 0
  0.5 0.5 0
</DataItem>
      </Geometry>
    </Grid>
  </Domain>
</Xdmf>

---  Now, what I want to do is to allow for the fact that the nodes
defining this plane, may happen to be labelled 300, 20, 22, 80 instead of
0->3.  The key point being that there is still only 4 nodes, not 300 in the
file for which I only need 4 to define the geom, but need to write out 300
to all for the 0-based implicit ordering.  Therefore, I'd like a section in
the geom part of the xmf file to qualify this numbering.  It doesn't bother
me if they're subsequently renumbered inside paraview/vtk, only that I
don't have to, as this is a simplistic version of something more
complicated.  So to be verbose, it should now look like:

<?xml version="1.0"?>
<!DOCTYPE Xdmf SYSTEM "Xdmf.dtd">
<Xdmf xmlns:xi="http://www.w3.org/2003/XInclude" Version="2.2">
  <Domain>
    <Grid GridType="Uniform">
      <Topology TopologyType="Quadrilateral" Dimensions="1">
        <DataItem Dimensions="1 4" NumberType="Int" Precision="8"
Format="XML">
          * 300 20 22 80 *
</DataItem>
      </Topology>
      <Geometry GeometryType="*XYZ_Explicit*">
        <DataItem Dimensions="4 3" NumberType="Float" Precision="4"
Format="XML">
*   20 -0.5 -0.5 0 *
*   22 0.5 -0.5 0 *
*   80 -0.5 0.5 0 *
*   300 0.5 0.5 0 *
 </DataItem>
      </Geometry>
    </Grid>
  </Domain>
</Xdmf>

Can this be done, or could this be done in the future?  Am I being daft and
there is an easy way to do this?

Cheers again,
Andy
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