Method GetCellBounds

Common/DataModel/vtkImageData.cxx:251–309

------------------------------------------------------------------------------ Fast implementation of GetCellBounds(). Bounds are calculated without constructing a cell.

// Fast implementation of GetCellBounds().  Bounds are calculated without
// constructing a cell.
void vtkImageData::GetCellBounds(vtkIdType cellId, double bounds[6])
{
  if (this->GetCells()->GetCellSize(cellId) == 0)
  {
    bounds[0] = bounds[1] = bounds[2] = bounds[3] = bounds[4] = bounds[5] = 0.0;
    return;
  }
  int ijkMin[3], ijkMax[3];
  vtkStructuredData::ComputeCellStructuredMinMaxCoords(
    cellId, this->GetDimensions(), ijkMin, ijkMax, this->GetDataDescription());

  vtkPoints* points = this->GetPoints();
  const auto pointsBackend =
    static_cast<vtkStructuredPointArray<double>*>(points->GetData())->GetBackend();
  int loc[3];
  double point[3];
  bounds[0] = bounds[2] = bounds[4] = VTK_DOUBLE_MAX;
  bounds[1] = bounds[3] = bounds[5] = VTK_DOUBLE_MIN;
  if (this->DirectionMatrixIsIdentity)
  {
    for (loc[2] = ijkMin[2]; loc[2] <= ijkMax[2]; loc[2]++)
    {
      point[2] = pointsBackend->mapStructuredZComponent(loc[2]);
      bounds[4] = std::min(bounds[4], point[2]);
      bounds[5] = std::max(bounds[5], point[2]);
    }
    for (loc[1] = ijkMin[1]; loc[1] <= ijkMax[1]; loc[1]++)
    {
      point[1] = pointsBackend->mapStructuredYComponent(loc[1]);
      bounds[2] = std::min(bounds[2], point[1]);
      bounds[3] = std::max(bounds[3], point[1]);
    }
    for (loc[0] = ijkMin[0]; loc[0] <= ijkMax[0]; loc[0]++)
    {
      point[0] = pointsBackend->mapStructuredXComponent(loc[0]);
      bounds[0] = std::min(bounds[0], point[0]);
      bounds[1] = std::max(bounds[1], point[0]);
    }
  }
  else
  {
    for (loc[2] = ijkMin[2]; loc[2] <= ijkMax[2]; loc[2]++)
    {
      for (loc[1] = ijkMin[1]; loc[1] <= ijkMax[1]; loc[1]++)
      {
        for (loc[0] = ijkMin[0]; loc[0] <= ijkMax[0]; loc[0]++)
        {
          pointsBackend->mapStructuredTuple(loc, point);
          bounds[0] = std::min(bounds[0], point[0]);
          bounds[1] = std::max(bounds[1], point[0]);
          bounds[2] = std::min(bounds[2], point[1]);
          bounds[3] = std::max(bounds[3], point[1]);
          bounds[4] = std::min(bounds[4], point[2]);
          bounds[5] = std::max(bounds[5], point[2]);
        }
      }
    }
  }