Re: [Libmesh-users] problems with mesh output: possible solution

[Michael P. <mpo...@pu...>]

On 06/13/2018 03:15 PM, John Peterson wrote:
>
>
> On Wed, Jun 13, 2018 at 11:03 AM, Michael Povolotskyi 
> <mpo...@pu... <mailto:mpo...@pu...>> wrote:
>
>     Hello John,
>
>     I played with it, and this is what worked for me.
>
>     #include <vector>
>     #include <sstream>
>     using namespace std;
>
>     #define private public//to get access to
>     libMesh::LibMeshInit._vtk_mpi_controller
>
>     #include "libmesh/mesh_generation.h"
>     #include "libmesh/mesh.h"
>     #include "libmesh/vtk_io.h"
>     #include "libmesh/libmesh.h"
>     #include "vtkMPIController.h"
>     int main(int argc, char ** argv)
>     {
>
>       MPI_Init(&argc, &argv);
>
>       {
>         libMesh::LibMeshInit init (argc, argv,MPI_COMM_WORLD);
>         int rank;
>         MPI_Comm_rank(MPI_COMM_WORLD, &rank);
>
>         vtkMPICommunicator* mcomm =
>     vtkMPICommunicator::GetWorldCommunicator()->NewInstance ();
>         mcomm->SplitInitialize (mcomm, rank, 0);
>
>         init._vtk_mpi_controller->SetCommunicator (mcomm);
>
>         libMesh::Mesh
>     mesh(libMesh::Parallel::Communicator(MPI_COMM_SELF));
>         libMesh::MeshTools::Generation::build_cube (mesh,
>     10, 10, 5, 0.0, 2.0, 0.0, 3.0, 0.0, 4.0,libMesh::HEX8);
>
>
>         if (rank == 0)
>         {
>           libMesh::VTKIO out(mesh);
>           out.write("mesh1.pvtu");
>         }
>       }
>       MPI_Finalize();
>       return 0;
>
>
>
>     }
>
>
>     What do you think? Can you provide an access to
>     libMesh::LibMeshInit._vtk_mpi_controller?
>     Or there is a better solution?
>
>
> I think it would be reasonable to provide a public accessor for 
> _vtk_mpi_controller, as long as we can still get away with a forward 
> declaration for vtkMPIController.
>
> Would it be possible to do the same algorithm from within 
> VTKIO::read()? At that point, we have a Communicator (mesh.comm()) for 
> the Mesh we are currently writing, so we could probably do the same 
> New/Split/Set series of steps there, but unfortunately we don't have 
> access to the LibMeshInit at that point...
>
> -- 
> John
Would you add the access to _vtk_mpi_controller for me?
I can do it myself, but I prefer to be consistent with you.

It looks to me that for a regular solution you need to reset the 
vtkMPICommunicator before any read/write event. Can you store the 
vtkMPICommunicator inside the mesh class?

Michael.