Method ExtractSelectedPoints

Filters/Extraction/vtkExtractSelection.cxx:969–1097

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//------------------------------------------------------------------------------
void vtkExtractSelection::ExtractSelectedPoints(
  vtkDataSet* input, vtkUnstructuredGrid* output, vtkSignedCharArray* pointInside, bool extractAll)
{
  vtkIdType numPts = input->GetNumberOfPoints();

  vtkPointData* pd = input->GetPointData();
  vtkPointData* outputPD = output->GetPointData();

  // To copy points in a type agnostic way later
  auto pointSet = vtkPointSet::SafeDownCast(input);

  outputPD->SetCopyGlobalIds(1);
  outputPD->CopyFieldOff("vtkOriginalPointIds");
  outputPD->CopyAllocate(pd);

  vtkNew<vtkIdTypeArray> originalPointIds;
  originalPointIds->SetNumberOfComponents(1);
  originalPointIds->SetName("vtkOriginalPointIds");
  outputPD->AddArray(originalPointIds);

  vtkNew<vtkPoints> newPts;
  if (!extractAll)
  {
    if (pointSet)
    {
      newPts->SetDataType(pointSet->GetPoints()->GetDataType());
    }
    vtkNew<vtkIdList> ids;
    ids->Allocate(numPts);
    vtkUnsignedCharArray* ghostArray = input->GetPointGhostArray();
    for (vtkIdType cc = 0; cc < numPts; ++cc)
    {
      if (ghostArray && ghostArray->GetValue(cc) == vtkDataSetAttributes::HIDDENPOINT)
      {
        // skip this point
        continue;
      }
      if (pointInside->GetValue(cc) != 0)
      {
        ids->InsertNextId(cc);
      }
    }
    const vtkIdType numNewPts = ids->GetNumberOfIds();
    // copy points
    newPts->SetNumberOfPoints(numNewPts);
    vtkSMPTools::For(0, numNewPts,
      [&](vtkIdType begin, vtkIdType end)
      {
        double point[3];
        auto idsPtr = ids->GetPointer(0);
        for (vtkIdType ptId = begin; ptId < end; ++ptId)
        {
          input->GetPoint(idsPtr[ptId], point);
          newPts->SetPoint(ptId, point);
        }
      });
    // copy point data
    outputPD->SetNumberOfTuples(numNewPts);