FindDegrees_SubtractLHE.h

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//  PURPOSE.  See the above copyright notice for more information.
//============================================================================
// Copyright (c) 2018, The Regents of the University of California, through
// Lawrence Berkeley National Laboratory (subject to receipt of any required approvals
// from the U.S. Dept. of Energy).  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification,
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//     Laboratory, U.S. Dept. of Energy nor the names of its contributors may be
//     used to endorse or promote products derived from this software without
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//=============================================================================
//
//  This code is an extension of the algorithm presented in the paper:
//  Parallel Peak Pruning for Scalable SMP Contour Tree Computation.
//  Hamish Carr, Gunther Weber, Christopher Sewell, and James Ahrens.
//  Proceedings of the IEEE Symposium on Large Data Analysis and Visualization
//  (LDAV), October 2016, Baltimore, Maryland.
//
//  The PPP2 algorithm and software were jointly developed by
//  Hamish Carr (University of Leeds), Gunther H. Weber (LBNL), and
//  Oliver Ruebel (LBNL)
//==============================================================================
 
#ifndef vtk_m_worklet_contourtree_augmented_contourtree_maker_inc_find_degrees_subtract_lhe_h
#define vtk_m_worklet_contourtree_augmented_contourtree_maker_inc_find_degrees_subtract_lhe_h
 
#include <vtkm/filter/scalar_topology/worklet/contourtree_augmented/Types.h>
#include <vtkm/worklet/WorkletMapField.h>
 
namespace vtkm
{
namespace worklet
{
namespace contourtree_augmented
{
namespace contourtree_maker_inc
{
 
// Worklet to subtract the LHE of each segment. This worklet is used for both the join and split tree.
// In the case of the join tre we should use the updegree as input and for the split tree the downdegree
class FindDegrees_SubtractLHE : public vtkm::worklet::WorkletMapField
{
public:
  typedef void ControlSignature(
    WholeArrayIn inNeighbour,      // (input)
    WholeArrayOut upOrDowndegree); // (output) updegree in the case of the
                                   //join tree and downdegree for the split tree
  typedef void ExecutionSignature(_1, InputIndex, _2);
  using InputDomain = _1;
 
 
  // Default Constructor
  VTKM_EXEC_CONT
  FindDegrees_SubtractLHE() {}
 
  template <typename InFieldPortalType, typename OutFieldPortalType>
  VTKM_EXEC void operator()(const InFieldPortalType& inNeighbourPortal,
                            const vtkm::Id joinOrSplitIndex,
                            const OutFieldPortalType& upOrDownDegreePortal) const
  {
    vtkm::Id whichJoinOrSplit = inNeighbourPortal.Get(joinOrSplitIndex);
    if (!NoSuchElement(whichJoinOrSplit))
    { // an actual neighbour
      // zero is always the LHE of a segment
      if (joinOrSplitIndex == 0)
        upOrDownDegreePortal.Set(whichJoinOrSplit,
                                 upOrDownDegreePortal.Get(whichJoinOrSplit) - joinOrSplitIndex + 1);
      else if (whichJoinOrSplit != inNeighbourPortal.Get(joinOrSplitIndex - 1))
        upOrDownDegreePortal.Set(whichJoinOrSplit,
                                 upOrDownDegreePortal.Get(whichJoinOrSplit) - joinOrSplitIndex + 1);
    } // an actual neighbour
 
    // In serial this worklet implements the following operation
    /*
        for (vtkm::Id joinIndex = 0; joinIndex < nActiveSupernodes; joinIndex++)
          { // per in edge index
            vtkm::Id whichJoin = inNeighbour[joinIndex];
            if (!NoSuchElement(whichJoin))
                    { // an actual neighbour
                    // zero is always the LHE of a segment
                    if (joinIndex == 0)
                            updegree[whichJoin] = updegree[whichJoin] - joinIndex + 1;
                    else if (whichJoin != inNeighbour[joinIndex-1])
                            updegree[whichJoin] = updegree[whichJoin] - joinIndex + 1;
                    } // an actual neighbour
          } // per in edge index
      */
  }
 
}; // FindDegrees_SubtractLHE
 
} // namespace contourtree_maker_inc
} // namespace contourtree_augmented
} // namespace worklet
} // namespace vtkm
 
#endif