Method RequestData

Filters/Parallel/vtkAlignImageDataSetFilter.cxx:114–188

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//------------------------------------------------------------------------------
int vtkAlignImageDataSetFilter::RequestData(
  vtkInformation*, vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  auto outputCD = vtkCompositeDataSet::GetData(outputVector, 0);
  outputCD->ShallowCopy(vtkDataObject::GetData(inputVector[0], 0));
  auto images = vtkCompositeDataSet::GetDataSets<vtkImageData>(outputCD);

  auto controller = this->GetController()
    ? vtk::MakeSmartPointer(this->GetController())
    : vtk::TakeSmartPointer<vtkMultiProcessController>(vtkDummyController::New());

  int countLocal = static_cast<int>(images.size());
  int countGlobal = countLocal;
  controller->AllReduce(&countLocal, &countGlobal, 1, vtkCommunicator::SUM_OP);
  if (countGlobal == 0)
  {
    // no images present. nothing to do.
    return 1;
  }

  // the origin that all output image datas will have
  vtkVector3d globalOrigin(VTK_DOUBLE_MAX);
  if (!::ComputeGlobalOrigin(globalOrigin, images, controller, this->MinimumExtent))
  {
    vtkErrorMacro("Failed to compute global origin.");
    return 0;
  }

  int illalignedOrigins = 0;
  // adjust image extents
  for (auto* image : images)
  {
    if (image->GetNumberOfPoints() == 0)
    {
      continue;
    }

    const vtkVector3d imgOrigin(image->GetOrigin());
    const vtkVector3d imgSpacing(image->GetSpacing());

    // we know the relationship is:
    // inputOrigin+inputExtent[any]*spacing=globalOrigin+outputExtent[any]*spacing
    // remember that spacing is the same for input and output imagedatas
    int outputExtent[6], inputExtent[6], dims[3];
    image->GetExtent(inputExtent);
    image->GetDimensions(dims);
    for (int cc = 0; cc < 3; ++cc)
    {
      outputExtent[2 * cc] = static_cast<int>(
        (imgOrigin[cc] + inputExtent[2 * cc] * imgSpacing[cc]) - globalOrigin[cc] / imgSpacing[cc]);
      // we compute the max extent based on the imagedata extent to reduce
      // the chance of round-off error that may change the number of
      // points and cells in the imagedata
      outputExtent[2 * cc + 1] = outputExtent[2 * cc] + dims[cc] - 1;
    }

    const vtkVector3d pt0(image->GetPoint(0));
    image->SetOrigin(globalOrigin.GetData());