Method ComputeSubExtents

Common/ExecutionModel/vtkExtentSplitter.cxx:225–331

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//------------------------------------------------------------------------------
int vtkExtentSplitter::ComputeSubExtents()
{
  // Assume success.
  int result = 1;

  vtkExtentSplitterInternals::SubExtentsType subExtents;
  int bestPriority;
  int dimensionality = 0;

  while (!this->Internal->Queue.empty())
  {
    // Pop the next extent off the queue.
    vtkExtentSplitterExtent e = this->Internal->Queue.front();
    this->Internal->Queue.pop();

    // In non-PointMode, intersections must have the same topological
    // dimension as the original extent.  This will prevent
    // high-priority source extents from repeatedly producing
    // single-point-wide intersections.
    if (!this->PointMode)
    {
      dimensionality = (((e.extent[1] - e.extent[0] > 0) ? 1 : 0) +
        ((e.extent[3] - e.extent[2] > 0) ? 1 : 0) + ((e.extent[5] - e.extent[4] > 0) ? 1 : 0));
    }

    // Intersect the extent with each extent source.
    subExtents.clear();
    bestPriority = -1;
    vtkExtentSplitterSubExtent se;
    for (vtkExtentSplitterInternals::SourcesType::const_iterator src =
           this->Internal->Sources.begin();
         src != this->Internal->Sources.end(); ++src)
    {
      se.source = src->first;
      if (this->IntersectExtents(e.extent, src->second.extent, se.extent) &&
        (this->PointMode ||
          (dimensionality ==
            (((se.extent[1] - se.extent[0] > 0) ? 1 : 0) +
              ((se.extent[3] - se.extent[2] > 0) ? 1 : 0) +
              ((se.extent[5] - se.extent[4] > 0) ? 1 : 0)))))
      {
        // Non-zero intersection volume.  Add the extent as a
        // candidate for best extent.
        if (src->second.priority > bestPriority)
        {
          // New highest priority.  Clear previous intersections with
          // lower priority.
          subExtents.clear();
          subExtents.push_back(se);
          bestPriority = src->second.priority;
        }
        else if (src->second.priority == bestPriority)
        {
          // Matching priority.  Add this intersection to the list.
          subExtents.push_back(se);
        }
      }
    }