Method Prepend

Filters/ParallelFlowPaths/vtkPStreamTracer.cxx:1838–1887

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
void vtkPStreamTracer::Prepend(vtkPolyData* pathPoly, vtkPolyData* headPoly)
{
  vtkCellArray* pathCells = pathPoly->GetLines();
  AssertEq(pathCells->GetNumberOfCells(), 1);
  AssertEq(headPoly->GetNumberOfPoints(), 1);

  double* newPoint = headPoly->GetPoint(0);
  AssertEq(
    headPoly->GetPointData()->GetNumberOfArrays(), pathPoly->GetPointData()->GetNumberOfArrays());

  const vtkIdType* path(nullptr);
  vtkIdType nPoints(0);
  pathCells->InitTraversal();
  pathCells->GetNextCell(nPoints, path);
  AssertNe(path, nullptr);
  AssertEq(nPoints, pathPoly->GetNumberOfPoints());

  vtkIdType newPointId = pathPoly->GetPoints()->InsertNextPoint(newPoint);

  vtkPointData* headData = headPoly->GetPointData();
  vtkPointData* pathData = pathPoly->GetPointData();
  Assert(SameShape(headData, pathData), "Prepend failure");

  int numArrays(headData->GetNumberOfArrays());
  for (int i = 0; i < numArrays; i++)
  {
    pathData->CopyTuple(
      headData->GetAbstractArray(i), pathData->GetAbstractArray(i), 0, newPointId);
  }

  PRINT("Prepend Point " << newPointId << " " << newPoint[0] << " " << newPoint[1] << " "
                         << newPoint[2]);
  vtkNew<vtkIdList> newPath;
  newPath->InsertNextId(newPointId);
  for (int i = 0; i < nPoints; i++)
  {
    newPath->InsertNextId(path[i]);
  }

  pathCells->Reset();
  if (newPath->GetNumberOfIds() > 1)
  {
    pathCells->InsertNextCell(newPath);
  }
  AssertEq(pathCells->GetNumberOfCells(), 1);
  vtkIdType newNumPoints(0);
  pathCells->GetNextCell(newNumPoints, path);
  AssertEq(newNumPoints, nPoints + 1);
  AssertEq(newNumPoints, pathPoly->GetNumberOfPoints());
}
VTK_ABI_NAMESPACE_END