[vtkusers] problem in writing data with vtkXMLMultiBlockDataWriter ...

[Ufuk Turuncoglu]

Hi,

I am trying to create very simple example of creating 
vtkMultiBlockDataSet using vtkStructuredGrid to sole a problem of mine 
in ParaView Catalyst. By this way, i could test some ideas without 
overhead of simulation code. In this case, i wrote following C++ code to 
demonstrate it. The problem is that the result test.vtm file includes 
information only one piece of data,

<?xml version="1.0"?>
<VTKFile type="vtkMultiBlockDataSet" version="1.0" 
byte_order="LittleEndian" header_type="UInt32" 
compressor="vtkZLibDataCompressor">
   <vtkMultiBlockDataSet>
     <Piece index="0">
       <DataSet index="1" file="test/test_1.vts">
       </DataSet>
     </Piece>
   </vtkMultiBlockDataSet>
</VTKFile>

but if i run the code with 4 core the test/ directory contains four 
file. I also observed that the file name written to test.vtm is changing 
based on the fastest core. So, i just wonder that am i missing something 
in here.

Thanks,
Regards,

--ufuk

#include <iostream>
#include "mpi.h"
#include "vtkStructuredGrid.h"
#include "vtkSmartPointer.h"
#include "vtkMultiBlockDataSet.h"
#include "vtkMultiPieceDataSet.h"
#include "vtkNew.h"
#include "vtkXMLMultiBlockDataWriter.h"

using namespace std;

// global variables
int const N = 10;
int const tileX = 2;
int const tileY = 2;

int main(int argc, char** argv) {
   // initialize MPI
   MPI_Init(NULL, NULL);

   // get number of processor and rank
   int nproc, myid;
   MPI_Comm_size(MPI_COMM_WORLD, &nproc);
   MPI_Comm_rank(MPI_COMM_WORLD, &myid);

   // create 2d decomposition parameters
   bool hasLeft = false, hasTop = false;
   if (myid%tileX == 0) hasLeft = true;
   if (myid/tileY == 0) hasTop = true;
   //cout << myid << " of " << nproc << " " << boolalpha << hasLeft << " 
" << hasTop << endl;

   // create structured grid
   vtkSmartPointer<vtkStructuredGrid> grid = 
vtkSmartPointer<vtkStructuredGrid>::New();

   // define grid coordinates
   vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
   points->SetNumberOfPoints(N/tileX*N/tileY);

   int istr = myid%tileX*N/tileX;
   int iend = istr+N/tileX-1;
   int jstr = myid/tileX*N/tileY;
   int jend = jstr+N/tileY-1;
   //cout << myid << " " << istr << " " << iend << " " << jstr << " " << 
jend << endl;

   int id = 0;
   for (int i = istr; i < iend; i++) {
     for (int j = jstr; j < jend; j++) {
       points->SetPoint(id, i, j, 0);
       id = id+1;
     }
   }

   grid->SetPoints(points);
   grid->SetExtent(istr, iend, jstr, jend, 0, 0);
   points->Delete();

   // create multi block grid
   vtkMultiBlockDataSet* mb = vtkMultiBlockDataSet::New();
   vtkNew<vtkMultiPieceDataSet> mpds;
   mpds->SetNumberOfPieces(nproc);
   mpds->SetPiece(myid, grid.GetPointer());
   mb->SetNumberOfBlocks(1);
   mb->SetBlock(0, mpds.GetPointer());

   // create a writer
   vtkSmartPointer<vtkXMLMultiBlockDataWriter> mbw = 
vtkSmartPointer<vtkXMLMultiBlockDataWriter>::New();
   mbw->SetFileName("test.vtm");
   mbw->SetDataModeToAscii();
   mbw->SetInputData(mb);
   mbw->Write();

   // finalize the MPI environment.
   MPI_Finalize();

   return 0;
}