[dune-pdelab] Writing subtree of a CompositeGridFunctionSpace to VTK

[Oliver Sander]

Am 22.06.2015 um 12:47 schrieb Jö Fahlke:
> Am Mon, 22. Jun 2015, 06:21:41 +0200 schrieb Oliver Sander:
>> Date: Mon, 22 Jun 2015 06:21:41 +0200
>> From: Oliver Sander <sander at igpm.rwth-aachen.de>
>> To: dune-pdelab mailing list <dune-pdelab at dune-project.org>
>> Subject: [dune-pdelab] Writing subtree of a CompositeGridFunctionSpace to
>>  VTK
>>
>> Dear pdelab team,
>> I have written a program that uses a CompositeGridFunctionSpace with two childen,
>> each of which is a VectorGridFunctionSpace.  Simulation results are written to
>> VTK using [roughly]
>>
>>   VTKWriter<GridView> vtkWriter(grid->leafGridView());
>>   VectorContainer x(compositeGFS);
>>   PDELab::addSolutionToVTKWriter(vtkWriter,compositeGFS,x);
>>
>> which works.  However, I actually only want the first subtree in the file.
>> How do I do that?
> 
> I'm not 100% certain, but I would try the GridFunctionSubspace:
> https://www.dune-project.org/doc-pdelab-2.0.0/doxygen/html/classDune_1_1PDELab_1_1GridFunctionSubSpace.html
> With that your code should become something like that:
> 
>   VTKWriter<GridView> vtkWriter(grid->leafGridView());
>   VectorContainer x(compositeGFS);
>   PDELab::GridFunctionSubSpace<GFS, TypeTree::TreePath<0> >
>     subGFS(stackobject_to_shared_ptr(compositeGFS));
>   PDELab::addSolutionToVTKWriter(vtkWriter,subGFS,x);
> 
> That is quite ugly.  Maybe Steffen knows a better way?

Thanks, Jö!  That works, and I don't even think it is ugly.

There is one problem, though: The first subtree my space is a displacement field.
When using my original code, that subtree appeared in ParaView as one data set 'displacement',
and I could use the warp-by-vector filter, for example.  When using the code snippet you
propose, the three components of the displacement appear as separate scalar fields 'displacement0',
'displacement1', 'displacement2'.  How can I keep them as a single data set?
Thanks,
Oliver




> 
> Regards,
> Jö.
> 


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