FindCriticalPointsFindSaddlesWorklet.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.
//
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//     Laboratory, U.S. Dept. of Energy nor the names of its contributors may be
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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_distributed_tree_grafter_find_critical_points_find_saddles_worklet_h
#define vtk_m_worklet_contourtree_distributed_tree_grafter_find_critical_points_find_saddles_worklet_h
 
 
#include <vtkm/filter/scalar_topology/worklet/contourtree_augmented/Types.h>
#include <vtkm/worklet/WorkletMapField.h>
 
namespace vtkm
{
namespace worklet
{
namespace contourtree_distributed
{
namespace tree_grafter
{
 
// Worklet used in TreeGrafter.FindCriticalPoints to find and flag saddles
class FindCriticalPointsFindSaddlesWorklet : public vtkm::worklet::WorkletMapField
{
public:
  using ControlSignature = void(
    FieldIn
      activeSuperarcs, // input iteration index. loop to one less than ContourTree->Supernodes.GetNumberOfValues()
    WholeArrayIn interiorForstIsNecessary, // input
    WholeArrayIn upNeighbour,              // input
    WholeArrayIn downNeighbour,            // input
    WholeArrayOut supernodeType            // output
  );
 
  using ExecutionSignature = void(_1, _2, _3, _4, _5);
  using InputDomain = _1;
 
  // Default Constructor
  VTKM_EXEC_CONT
  FindCriticalPointsFindSaddlesWorklet() {}
 
  template <typename InFieldPortalType, typename OutFieldPortalType>
  VTKM_EXEC void operator()(const vtkm::worklet::contourtree_augmented::EdgePair& activeSuperarc,
                            const InFieldPortalType& isNecessaryPortal,
                            const InFieldPortalType& upNeighbourPortal,
                            const InFieldPortalType& downNeighbourPortal,
                            const OutFieldPortalType& supernodeTypePortal) const
  { // operator ()
    // per active superarc
    // retrieve the ends again
    vtkm::Id lowEnd = activeSuperarc.first;
    vtkm::Id highEnd = activeSuperarc.second;
 
    // if the low end doesn't have the high end as the up neighbour, another arc succeeded in writing to it
    // which guarantees that it is a saddle (or an attachment - but we exclude that by testing it)
    if (!isNecessaryPortal.Get(lowEnd) && (upNeighbourPortal.Get(lowEnd) != highEnd))
    {
      supernodeTypePortal.Set(lowEnd, (vtkm::Id)vtkm::worklet::contourtree_augmented::IS_SADDLE);
    }
 
    // symmetrically for the high end
    if (!isNecessaryPortal.Get(highEnd) && (downNeighbourPortal.Get(highEnd) != lowEnd))
    {
      supernodeTypePortal.Set(highEnd, (vtkm::Id)vtkm::worklet::contourtree_augmented::IS_SADDLE);
    }
 
    // In serial this worklet implements the following operation
    /*
    // now test whether they match what we expect: if not, we've found a saddle
    for (indexType activeSuper = 0; activeSuper < activeSuperarcs.size(); activeSuper++)
      { // per active superarc
      // retrieve the ends again
      indexType lowEnd = activeSuperarcs[activeSuper].low;
      indexType highEnd = activeSuperarcs[activeSuper].high;
 
      // if the low end doesn't have the high end as the up neighbour, another arc succeeded in writing to it
      // which guarantees that it is a saddle (or an attachment - but we exclude that by testing it)
      if (!residue->isNecessary[lowEnd] && (upNeighbour[lowEnd] != highEnd))
        supernodeType[lowEnd] = IS_SADDLE;
 
      // symmetrically for the high end
      if (!residue->isNecessary[highEnd] && (downNeighbour[highEnd] != lowEnd))
        supernodeType[highEnd] = IS_SADDLE;
      } // per active superarc
    */
  } // operator ()
 
}; // FindCriticalPointsFindSaddlesWorklet
 
} // namespace tree_grafter
} // namespace contourtree_distributed
} // namespace worklet
} // namespace vtkm
 
#endif