[vtkusers] CopyAllocate

[McClennan, Scott Andrew]

Hi,

I'm trying to divide a large vtkStructuredGrid data set into smaller vtkUnstructuredGrid data sets to plot individually, but I do not want to make deep copies of the data.  Is there a way to map cell data from the original data set to a sub-grid?

I think vtkDataSetAttributes::CopyAllocate() should help me, but it doesn't work as I think it should.  I pasted the code I have so far below, which does indeed divide the grid up and I don't think it makes deep copies, but the colors are not mapped properly to the sub-grid.  Can anyone help?

Thanks,

Scott

PS. I made the MaterialGridFilter to do what I think vtkThreshold should do, but it didn't seem to work for me.

...
            std::vector< vtkSmartPointer<vtkUnstructuredGrid> > usgVector;
            VTK_NEW_PTR(pusg,vtkUnstructuredGrid);
            pusg->SetPoints(points);
            pusg->Update();
            for(int ic=0; ic<nmat-1; ic++){
                  usgVector.push_back(pusg);
            }
            MaterialGridFilter(usgVector,sgrid);
...

void MaterialGridFilter(std::vector< vtkSmartPointer<vtkUnstructuredGrid> > & usgVector, vtkSmartPointer<vtkStructuredGrid> & sgrid){
      int nmat = usgVector.size();
      // set up cell data for each material
      std::vector< vtkSmartPointer<vtkCellArray> > caVector;
      VTK_NEW_PTR(polys,vtkCellArray);
      for(int ic=0;ic<nmat;ic++){
            caVector.push_back(polys);
      }
      // loop through cells in the base grid
      int niel=nd1-1,njel=nd2-1,nkel=nd3-1;
      if (niel==0) niel=1;
      if (njel==0) njel=1;
      if (nkel==0) nkel=1;
      int nel=niel*njel*nkel;
      int iel=0;
      int imat=0;

      int cid=0;
      VTK_NEW_PTR(nodelist,vtkIdList);
      sgrid->Print(cout);
      for(int k=0; k<nkel; k++){
            for(int j=0; j<njel; j++){
                  for(int i=0; i<niel; i++){
                        imat = (int)sgrid->GetCellData()->GetScalars()->GetComponent(iel,0);
                        // construct Unstructured grid cell
                        if(imat<nmat){
                        cid=caVector[imat]->InsertNextCell(sgrid->GetCell(iel));
                        }
                        iel++;
                  }
            }
      }

      // loop through materials and set cell data for each unstructured grid
      vtkCellData *pd = sgrid->GetCellData();
      int isize=0;
      for(int ic=0;ic<nmat;ic++){
            usgVector[ic]->SetCells(12,caVector[ic]);
            isize = usgVector[ic]->GetNumberOfCells();
            usgVector[ic]->GetCellData()->CopyAllocate(pd,isize,0,1);
            usgVector[ic]->GetCellData()->CopyData(pd,1,1);
            usgVector[ic]->Update();
            usgVector[ic]->Print(cout);
      }

}


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