Method ProcessRectilinearGrid

Filters/General/vtkAxisAlignedTransformFilter.cxx:767–861

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//----------------------------------------------------------------------------
bool vtkAxisAlignedTransformFilter::ProcessRectilinearGrid(
  vtkRectilinearGrid* inputRG, vtkRectilinearGrid* outputRG, int rotationMatrix[3][3])
{
  outputRG->DeepCopy(inputRG);
  ::ApplyScale(outputRG, Scale);
  if (RotationAngle == ROT0)
  {
    ::ApplyTranslation(outputRG, Translation);
    return true;
  }

  int dims[3];
  outputRG->GetDimensions(dims);

  if (outputRG->GetDataDimension() == 1)
  {
    vtkErrorMacro("Rotations for 1D RectilinearGrid are not supported.");
    return false;
  }

  // Swap dimensions according to rotation
  int newDims[3];
  std::memcpy(newDims, dims, 3 * sizeof(int));
  for (int i = 0; i < 3; ++i)
  {
    for (int j = 0; j < 3; ++j)
    {
      if (rotationMatrix[i][j] != 0)
      {
        newDims[i] = dims[j];
        break;
      }
    }
  }

  vtkDoubleArray* XCoordinate = vtkDoubleArray::SafeDownCast(outputRG->GetXCoordinates());
  vtkDoubleArray* YCoordinate = vtkDoubleArray::SafeDownCast(outputRG->GetYCoordinates());
  vtkDoubleArray* ZCoordinate = vtkDoubleArray::SafeDownCast(outputRG->GetZCoordinates());

  // Compute a translation vector for inverted dimensions
  // after the rotation to stay in the positive quadrant
  int tvec[3] = { 0, 0, 0 };
  for (int i = 0; i < 3; i++)
  {
    for (int j = 0; j < 3; j++)
    {
      if (rotationMatrix[i][j] < 0)
      {
        tvec[j] += std::max(newDims[i] - 1, 1) - 1;
        ::ReverseAxes(j, XCoordinate, YCoordinate, ZCoordinate);
      }
    }
  }

  outputRG->SetDimensions(newDims[0], newDims[1], newDims[2]);
  XCoordinate->Register(nullptr);
  YCoordinate->Register(nullptr);
  ZCoordinate->Register(nullptr);