[vtkusers] is whole extent required for multiblock dataset?

[Ufuk Turuncoglu]

Hi Again,

I create following test code to write dummy data (checkerboard with 0 
and 1) using vtkStructuredGrid in multiblock format. Without extent in 
left and top of the tiles the data looks correct but there is a gap 
between pieces (see attached screenshot). To fix the issue, i add a 
extra piece of code to overlap one row and columns (using hasLeft and 
hasTop control). The problem is that when i run the code with this 
modification, i am getting totally wrong grid representation (screen2). 
I just wonder that do i need to set whole extent in somewhere. I tried 
to add following to set whole extent to multiblock dataset,

int extent[6] = {0, N-1, 0, N-1, 0, 0};
mb->GetInformationObject(0)->Set(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(), 
extent, 6);

but it won't work as i expected. Any suggestion? Thanks.

Regards,

--ufuk


#include <iostream>
#include "mpi.h"
#include "vtkStructuredGrid.h"
#include "vtkSmartPointer.h"
#include "vtkMultiBlockDataSet.h"
#include "vtkMultiPieceDataSet.h"
#include "vtkNew.h"
#include "vtkXMLPMultiBlockDataWriter.h"
#include "vtkMPIController.h"
#include "vtkDoubleArray.h"
#include "vtkDataSet.h"
#include "vtkPointData.h"
#include "vtkInformation.h"
#include "vtkStreamingDemandDrivenPipeline.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);

   // setup global controller, true means initialized externally
   vtkNew<vtkMPIController> controller;
   controller->Initialize(&argc, &argv, true);
vtkMultiProcessController::SetGlobalController(controller.Get());

   // 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;

   int istr = myid%tileX*N/tileX;
   int iend = istr+N/tileX-1;
   if (hasLeft) iend = iend+1;
   int jstr = myid/tileX*N/tileY;
   int jend = jstr+N/tileY-1;
   if (hasTop) jend = jend+1;
   int size = (iend-istr+1)*(jend-jstr+1);
   //cout << myid << " of " << nproc << " " << boolalpha << hasLeft << " 
" << hasTop << endl;
   //cout << myid << " " << istr << " " << iend << " " << jstr << " " << 
jend << endl;

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

   // define grid coordinates
   vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
   points->SetNumberOfPoints(size);

   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();

   // add field, checkerboard type data with full of 0/1
   vtkSmartPointer<vtkDoubleArray> field = 
vtkSmartPointer<vtkDoubleArray>::New();
   field->SetName("dummy");
   field->SetNumberOfComponents(1);
   field->SetNumberOfValues(size);

   id = 0;
   for (int i = istr; i <= iend; i++) {
     for (int j = jstr; j <= jend; j++) {
       int val = (i+j)%2 ? 0 : 1;
       field->SetValue(id, val);
       id = id+1;
     }
   }

   // 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());

   // add field
   vtkDataSet *ds = vtkDataSet::SafeDownCast(mpds->GetPiece(myid));
   ds->GetPointData()->AddArray(field);

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

   // finalize the MPI environment.
   MPI_Finalize();

   return 0;
}
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