Method RequestData

Filters/ParallelMPI/vtkPExtractGrid.cxx:85–238

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
int vtkPExtractGrid::RequestData(
  vtkInformation* request, vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  DEBUG_OUT("########### RequestData\n");

  bool isSubSampling =
    this->SampleRate[0] != 1 || this->SampleRate[1] != 1 || this->SampleRate[2] != 1;

  // No MPI, or no subsampling? Just run the serial implementation.
  if (!this->Controller || !isSubSampling)
  {
    return this->Superclass::RequestData(request, inputVector, outputVector);
  }

  if (!this->Internal->IsValid())
  {
    return 0;
  }

  // Collect information:
  vtkInformation* inInfo = inputVector[0]->GetInformationObject(0);
  vtkInformation* outInfo = outputVector->GetInformationObject(0);

  int inputWholeExtent[6];
  inInfo->Get(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(), inputWholeExtent);
  int outputWholeExtent[6];
  outInfo->Get(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(), outputWholeExtent);

  vtkStructuredGrid* input =
    vtkStructuredGrid::SafeDownCast(inInfo->Get(vtkDataObject::DATA_OBJECT()));
  vtkStructuredGrid* output =
    vtkStructuredGrid::SafeDownCast(outInfo->Get(vtkDataObject::DATA_OBJECT()));

  int inputExtent[6];
  input->GetExtent(inputExtent);

  // Clamp the global VOI to the whole extent:
  int globalVOI[6];
  std::copy(this->VOI, this->VOI + 6, globalVOI);
  vtkStructuredExtent::Clamp(globalVOI, inputWholeExtent);

  // 1D Example:
  //   InputWholeExtent = [0, 20]
  //   GlobalVOI = [3, 17]
  //   SampleRate = 2
  //   OutputWholeExtent = [0, 7]
  //   Processes = 2
  //
  // Process 0:
  //   PartitionedInputExtent = [0, 10]
  //   PartitionedVOI = [3, 9] (due to sampling)
  //   OutputExtent = [0, 3]
  //   SerialOutputExtent = [0, 3]
  //   FinalOutputExtent = [0, 4] (after gap closing)
  //
  // Process 1:
  //   PartitionedInputExtent = [10, 20]
  //   PartitionedVOI = [11, 17] (offset due to sampling)