Function GatherMidpoints

IO/ParallelNetCDF/vtkPSLACReader.cxx:232–293

------------------------------------------------------------------------------ Convenience function for gathering midpoint information to a process.

//------------------------------------------------------------------------------
// Convenience function for gathering midpoint information to a process.
void GatherMidpoints(vtkMultiProcessController* controller, const midpointListsType& sendMidpoints,
  midpointListsType& recvMidpoints, int process)
{
  vtkIdType sendLength = static_cast<vtkIdType>(sendMidpoints.position.size());
  if (sendLength != static_cast<vtkIdType>(sendMidpoints.topology.size()))
  {
    vtkGenericWarningMacro(<< "Bad midpoint array structure.");
    return;
  }

  vtkIdType numProcesses = controller->GetNumberOfProcesses();

  // Gather the amount of data each process is going to send.
  std::vector<vtkIdType> receiveCounts(numProcesses);
  controller->Gather(&sendLength, &receiveCounts.at(0), 1, process);

  // Get ready the arrays for the receiver that determine how much data
  // to get and where to put it.
  std::vector<vtkIdType> positionLengths(numProcesses);
  std::vector<vtkIdType> positionOffsets(numProcesses);
  std::vector<vtkIdType> topologyLengths(numProcesses);
  std::vector<vtkIdType> topologyOffsets(numProcesses);

  const double* sendPositionBuffer =
    ((sendLength > 0) ? reinterpret_cast<const double*>(&sendMidpoints.position.at(0)) : nullptr);
  const vtkIdType* sendTopologyBuffer =
    ((sendLength > 0) ? reinterpret_cast<const vtkIdType*>(&sendMidpoints.topology.at(0))
                      : nullptr);
  double* recvPositionBuffer;
  vtkIdType* recvTopologyBuffer;

  if (process == controller->GetLocalProcessId())
  {
    vtkIdType numEntries = 0;
    for (int i = 0; i < numProcesses; i++)
    {
      positionLengths[i] = midpointPositionSize * receiveCounts[i];
      positionOffsets[i] = midpointPositionSize * numEntries;
      topologyLengths[i] = midpointTopologySize * receiveCounts[i];
      topologyOffsets[i] = midpointTopologySize * numEntries;
      numEntries += receiveCounts[i];
    }
    recvMidpoints.position.resize(numEntries);
    recvMidpoints.topology.resize(numEntries);

    recvPositionBuffer =
      ((numEntries > 0) ? reinterpret_cast<double*>(&recvMidpoints.position.at(0)) : nullptr);
    recvTopologyBuffer =
      ((numEntries > 0) ? reinterpret_cast<vtkIdType*>(&recvMidpoints.topology.at(0)) : nullptr);
  }
  else
  {
    recvPositionBuffer = nullptr;
    recvTopologyBuffer = nullptr;
  }

  // Gather the actual data.
  controller->GatherV(sendPositionBuffer, recvPositionBuffer, midpointPositionSize * sendLength,