Function SetMixedPolyhedralCells

IO/CatalystConduit/vtkConduitToDataObject.cxx:892–967

* See CreateMixedUnstructuredGrid. */

 * See CreateMixedUnstructuredGrid.
 */
void SetMixedPolyhedralCells(
  vtkUnstructuredGrid* ug, vtkDataArray* shapes, vtkCellArray* elements, vtkCellArray* subelements)
{
  // if there are no subelements
  if (!subelements || subelements->GetNumberOfCells() == 0)
  {
    // This is a simple case where we have a mixed cell type, but no polyhedra.
    ug->SetPolyhedralCells(shapes, elements, nullptr, nullptr);
    return;
  }

  vtkNew<vtkCellArray> connectivity;
  vtkNew<vtkCellArray> faces;
  vtkNew<vtkCellArray> faceLocations;
  subelements->IsStorage64Bit()
    ? faces->ConvertTo64BitStorage() && faceLocations->ConvertTo64BitStorage()
    : faces->ConvertTo64BitStorage() && faceLocations->ConvertTo32BitStorage();

  connectivity->AllocateEstimate(elements->GetNumberOfCells(), 10);
  faces->AllocateExact(
    subelements->GetNumberOfCells(), subelements->GetConnectivityArray()->GetNumberOfTuples());
  faceLocations->AllocateExact(elements->GetNumberOfCells(), subelements->GetNumberOfCells());

  vtkIdType numCellFaces, numFacePointIDs, numCellPointIDs;
  const vtkIdType *cellGlobalFaceIDs, *facePointIDs, *cellPointIDs;
  std::set<vtkIdType> cellPointIDsSet;
  vtkIdType globalFaceId = 0;
  auto cellTypes = vtk::DataArrayValueRange<1, unsigned char>(shapes);
  for (vtkIdType i = 0, numCells = elements->GetNumberOfCells(); i < numCells; ++i)
  {
    const unsigned char& cellType = cellTypes[i];
    if (cellType == VTK_POLYHEDRON)
    {
      cellPointIDsSet.clear();
      // https://llnl-conduit.readthedocs.io/en/latest/blueprint_mesh.html#polyhedra
      // This in conduit describes a polyhedron' global face IDs, and not its point IDs.
      // Even after https://gitlab.kitware.com/vtk/vtk/-/issues/18190 was resolved, the conduit
      // format is still different from the VTK format, so we need to do some conversions for VTK.
      elements->GetCellAtId(i, numCellFaces, cellGlobalFaceIDs);

      faceLocations->InsertNextCell(numCellFaces);
      for (vtkIdType j = 0; j < numCellFaces; ++j)
      {
        faceLocations->InsertCellPoint(globalFaceId++);

        subelements->GetCellAtId(cellGlobalFaceIDs[j], numFacePointIDs, facePointIDs);
        // If VTK' polyhedron format had a notion of global face IDs, we could just use
        // subelements as faces, instead of copying each face, but sadly that's not true.
        faces->InsertNextCell(numFacePointIDs, facePointIDs);
        // accumulate point IDs from all faces in this polyhedron
        cellPointIDsSet.insert(facePointIDs, facePointIDs + numFacePointIDs);
      }

      // Insert the points IDs of this polyhedron into the 'connectivity' array.
      connectivity->InsertNextCell(static_cast<int>(cellPointIDsSet.size()));
      for (const auto& pt : cellPointIDsSet)
      {
        connectivity->InsertCellPoint(pt);