Copying geometry from poly data clipper to another polydata using original IDs from ID filter

Support
1

Hey! I am looking to copy existing geometry inside a clipper from one polydata to another polydata, using original IDs from vtkIdFilter. I can get the original Ids from the filter, but how would I get around to copying the geometry inside the clipper to the second polydata? All my attempts at iterating over the cells or points are causing the program to crash (i.e. I can’t even create new cells and points into the other polydata so it may be I’m doing something fundamentally wrong). Is there a way to use DeepCopy or ShallowCopy so that it does not reset the second polydata when copying from first to second polydata?

2

Hey, I have gotten one version partially working. Problem is, it only copies the geometry on the first click - if I click again no new geometry copied is visible. Number of points and cells does grow in the poly data to be copied to. Any help would be greatly appreciated!

if (this->selectionModelPolyData->GetPoints() == 0) {
    vtkNew<vtkPoints> initialPoints;
    this->selectionModelPolyData->SetPoints(initialPoints);
}

if (this->selectionModelPolyData->GetNumberOfCells() == 0) {
    vtkNew<vtkCellArray> initialArray;
    this->selectionModelPolyData->SetPolys(initialArray);
}

// Copy new cells from clipped area
this->selectionModelPolyData->BuildLinks();
vtkSmartPointer<vtkCellIterator> iter = clipped->NewCellIterator();

for (iter->InitTraversal(); !iter->IsDoneWithTraversal(); iter->GoToNextCell())
{
    vtkNew<vtkGenericCell> cell;
    iter->GetCell(cell);

    vtkSmartPointer<vtkPoints> iter_points = iter->GetPoints();
    vtkNew<vtkTriangle> tri;
    vtkNew<vtkIdList> temp_pts;

    // Set new IDs for triangle
    for (vtkIdType i = 0; i < iter_points->GetNumberOfPoints(); i++) {
        double pos[3];
        iter_points->GetPoint(i, pos);

        vtkIdType id = this->selectionModelPolyData->GetPoints()->InsertNextPoint(pos);
        
        // Insert point ids for cell
        for (vtkIdType y = 0; y < iter_points->GetNumberOfPoints(); y++) {
            tri->GetPointIds()->SetId(y, id);
        }
        temp_pts->InsertNextId(id);
    }
    
    this->selectionModelPolyData->InsertNextCell(VTKCellType::VTK_TRIANGLE, temp_pts);
}

this->selectionModelPolyData->Modified();