Method SplitExtentByPoints

Common/ExecutionModel/vtkExtentTranslator.cxx:223–308

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int vtkExtentTranslator::SplitExtentByPoints(int piece, int numPieces, int* ext, int splitMode)
{
  int numPiecesInFirstHalf;
  int size[3], splitAxis;
  vtkLargeInteger mid;

  // keep splitting until we have only one piece.
  // piece and numPieces will always be relative to the current ext.
  while (numPieces > 1)
  {
    // Get the dimensions for each axis.
    size[0] = ext[1] - ext[0] + 1;
    size[1] = ext[3] - ext[2] + 1;
    size[2] = ext[5] - ext[4] + 1;
    // choose what axis to split on based on the SplitMode
    // if the user has requested x, y, or z slabs then try to
    // honor that request. If that axis is already split as
    // far as it can go, then drop to block mode.
    if (splitMode < 3 && size[splitMode] > 1)
    {
      splitAxis = splitMode;
    }
    // otherwise use block mode
    else
    {
      if (size[2] >= size[1] && size[2] >= size[0] && size[2] / 2 >= 1)
      {
        splitAxis = 2;
      }
      else if (size[1] >= size[0] && size[1] / 2 >= 1)
      {
        splitAxis = 1;
      }
      else if (size[0] / 2 >= 1)
      {
        splitAxis = 0;
      }
      else
      {
        // signal no more splits possible
        splitAxis = -1;
      }
    }

    if (splitAxis == -1)
    {
      // can not split any more.
      if (piece == 0)
      {
        // just return the remaining piece
        numPieces = 1;
      }
      else
      {
        // the rest must be empty
        return 0;
      }
    }