Method GetNextCells

Rendering/Core/vtkCellCenterDepthSort.cxx:183–239

}

vtkIdTypeArray* vtkCellCenterDepthSort::GetNextCells()
{
  if (this->ToSort->Stack.empty())
  {
    // Already sorted and returned everything.
    return nullptr;
  }

  vtkIdType* cellIds = this->SortedCells->GetPointer(0);
  float* cellDepths = this->CellDepths->GetPointer(0);
  vtkIdPair partition;

  partition = this->ToSort->Stack.top();
  this->ToSort->Stack.pop();
  while (partition.second - partition.first > this->MaxCellsReturned)
  {
    vtkIdType left = partition.first;
    vtkIdType right = partition.second - 1;
    float pivot = cellDepths[static_cast<vtkIdType>(vtkMath::Random(left, right))];
    while (left <= right)
    {
      while ((left <= right) && (cellDepths[left] < pivot))
        left++;
      while ((left <= right) && (cellDepths[right] > pivot))
        right--;

      if (left > right)
        break;

      std::swap(cellIds[left], cellIds[right]);
      std::swap(cellDepths[left], cellDepths[right]);

      left++;
      right--;
    }

    this->ToSort->Stack.emplace(left, partition.second);
    partition.second = left;
  }

  if (partition.second <= partition.first)
  {
    // Got a partition of zero size.  Just recurse to get the next one.
    return this->GetNextCells();
  }

  vtkIdType firstcell = partition.first;
  vtkIdType numcells = partition.second - partition.first;

  this->SortedCellPartition->SetArray(cellIds + firstcell, numcells, 1);
  this->SortedCellPartition->SetNumberOfTuples(numcells);
  this->CellPartitionDepths->SetArray(cellDepths + firstcell, numcells, 1);
  this->CellPartitionDepths->SetNumberOfTuples(numcells);

  vtkSortDataArray::Sort(this->CellPartitionDepths, this->SortedCellPartition);
  return this->SortedCellPartition;
}
VTK_ABI_NAMESPACE_END