Method ComputeMagnitudeCellData

Rendering/VolumeOpenGL2/vtkSmartVolumeMapper.cxx:549–586

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//------------------------------------------------------------------------------
void vtkSmartVolumeMapper::ComputeMagnitudeCellData(vtkDataSet* input, vtkDataArray* arr)
{
  vtkImageData* imData = vtkImageData::SafeDownCast(input);
  if (!imData)
  {
    // TODO: Support image magnitude calculation for rectilinear grids
    return;
  }

  vtkNew<vtkImageData> tempInput;
  tempInput->ShallowCopy(imData);

  tempInput->GetCellData()->SetActiveAttribute(arr->GetName(), vtkDataSetAttributes::SCALARS);

  // vtkImageMagnitude can only process point data so, data is transformed first
  // to points and then back to cells.
  vtkNew<vtkCellDataToPointData> cellToPoints;
  cellToPoints->SetInputData(tempInput);
  cellToPoints->Update();
  tempInput->ShallowCopy(cellToPoints->GetOutput());

  const int id =
    tempInput->GetPointData()->SetActiveAttribute(arr->GetName(), vtkDataSetAttributes::SCALARS);
  if (id < 0)
  {
    vtkErrorMacro("Failed to set the active attribute in vtkImageMagnitude's input"
                  " (from cellToPoints)!");
    return;
  }

  this->ImageMagnitude->SetInputData(tempInput);
  this->ImageMagnitude->Update();

  vtkNew<vtkPointDataToCellData> pointsToCells;
  pointsToCells->SetInputConnection(this->ImageMagnitude->GetOutputPort());
  pointsToCells->Update();
  this->InputDataMagnitude->ShallowCopy(pointsToCells->GetOutput());
}

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void vtkSmartVolumeMapper::ComputeMagnitudePointData(vtkDataSet* input, vtkDataArray* arr)