[petsc-dev] DMDA VTK viewer regression: field names missing

[Matthew Knepley]

On Wed, Mar 27, 2019 at 10:56 PM Jed Brown via petsc-dev <
petsc-dev at mcs.anl.gov> wrote:

> Prior to this PR, which was merged for 3.10
>
>
> https://bitbucket.org/petsc/petsc/pull-requests/1029/dmda-vtk-viewing-output-multiple-dof/diff
>   https://bitbucket.org/petsc/petsc/commits/ea2d7708fa6
>
> we could have files that look like the following, and thus were easy to
> navigate in Paraview and Visit.
>

Tell me if I am wrong (since I do not run it this way). I think the point
of Patrick's change is a good one, and
necessary to view things with DMStag. What Jed dislikes, rightly, is that
some metadata has gone missing.
Does Xdmf allow you to name the components? The way I do this
petsc_gen_xdmf.py is to write the whole
thing as Patrick does, but then create views into the data using the
component names. It sound like this should
be doable here.

   Matt


> <VTKFile type="StructuredGrid" version="0.1" byte_order="LittleEndian">
>   <StructuredGrid WholeExtent="0 12 0 24 0 24">
>     <Piece Extent="0 12 0 24 0 24">
>       <Points>
>         <DataArray type="Float64" Name="Position" NumberOfComponents="3"
> format="appended" offset="0" />
>       </Points>
>       <PointData Scalars="ScalarPointData">
>         <DataArray type="Float64" Name="Density" NumberOfComponents="1"
> format="appended" offset="195004" />
>         <DataArray type="Float64" Name="MomentumX" NumberOfComponents="1"
> format="appended" offset="260008" />
>         <DataArray type="Float64" Name="MomentumY" NumberOfComponents="1"
> format="appended" offset="325012" />
>         <DataArray type="Float64" Name="MomentumZ" NumberOfComponents="1"
> format="appended" offset="390016" />
>         <DataArray type="Float64" Name="Total Energy"
> NumberOfComponents="1" format="appended" offset="455020" />
>       </PointData>
>     </Piece>
>   </StructuredGrid>
>   <AppendedData encoding="raw">
>
> Now the same viewer setup and VecView yields a file that is far more
> opaque and requires the user to remember what all the field numbers
> mean.
>
> <VTKFile type="StructuredGrid" version="0.1" byte_order="LittleEndian">
>   <StructuredGrid WholeExtent="0 12 0 24 0 24">
>     <Piece Extent="0 12 0 24 0 24">
>       <Points>
>         <DataArray type="Float64" Name="Position" NumberOfComponents="3"
> format="appended" offset="0" />
>       </Points>
>       <PointData Scalars="ScalarPointData">
>         <DataArray type="Float64" Name="Unnamed Vec data"
> NumberOfComponents="5" format="appended" offset="195004" />
>       </PointData>
>     </Piece>
>   </StructuredGrid>
>   <AppendedData encoding="raw">
>
>
> Do others consider this a regression?  Is it feasible to fix for 3.11?
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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