SetUpAndDownNeighboursWorklet.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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// (1) Redistributions of source code must retain the above copyright notice, this
//     list of conditions and the following disclaimer.
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// (3) Neither the name of the University of California, Lawrence Berkeley National
//     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_bract_maker_set_up_and_down_neighbours_worklet_h
#define vtk_m_worklet_contourtree_distributed_bract_maker_set_up_and_down_neighbours_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 bract_maker
{
 
class SetUpAndDownNeighboursWorklet : public vtkm::worklet::WorkletMapField
{
public:
  using ControlSignature = void(WholeArrayIn bractVertexSuperset, // input
                                FieldIn bractSuperarcs,           // input
                                WholeArrayIn meshSortIndex,       // input
                                WholeArrayOut upNeighbour,        // output
                                WholeArrayOut downNeighbour       // output
  );
  using ExecutionSignature = void(InputIndex, _2, _1, _3, _4, _5);
  using InputDomain = _1;
 
  // Default Constructor
  VTKM_EXEC_CONT
  SetUpAndDownNeighboursWorklet() {}
 
  // We use a separate MeshSortIndexPortalType (also it may strictly not be necessary) because
  // the ContourTreeMehs uses a ArrayHandleIndex for its SortIndex and the other mesh types
  // use a IdArrayType (i.e., ArrayHandle<vtkm::Id>
  template <typename InFieldPortalType,
            typename MeshSortIndexPortalType,
            typename OutFieldPortalType>
  VTKM_EXEC void operator()(const vtkm::Id& from,
                            const vtkm::Id& to,
                            const InFieldPortalType& bractVertexSupersetPortal,
                            const MeshSortIndexPortalType& meshSortIndexPortal,
                            const OutFieldPortalType& upNeighbourPortal,
                            const OutFieldPortalType& downNeighbourPortal) const
  {
    // per vertex
    // ignore the last terminating edge
    if (vtkm::worklet::contourtree_augmented::NoSuchElement(to))
    {
      return;
    }
 
    // now find the sort index of the from and to
    vtkm::Id fromSort = meshSortIndexPortal.Get(bractVertexSupersetPortal.Get(from));
    vtkm::Id toSort = meshSortIndexPortal.Get(bractVertexSupersetPortal.Get(to));
 
    // use this to identify direction of edge
    if (fromSort < toSort)
    { // from is lower
      upNeighbourPortal.Set(from, to);
      downNeighbourPortal.Set(to, from);
    } // from is lower
    else
    { // to is lower
      upNeighbourPortal.Set(to, from);
      downNeighbourPortal.Set(from, to);
    } // to is lower
    // In serial this worklet implements the following operation
    /*
    //  a.  Loop through all of the superarcs in the return tree, retrieving the two ends
    for (indexType from = 0; from < bractVertexSuperset.size(); from++)
    { // per vertex
      indexType to = bract->superarcs[from];
      // ignore the last terminating edge
      if (noSuchElement(to))
        continue;
      // now find the sort index of the from and to
      indexType fromSort = mesh->SortIndex(bractVertexSuperset[from]);
      indexType toSort = mesh->SortIndex(bractVertexSuperset[to]);
 
      // use this to identify direction of edge
      if (fromSort < toSort)
        { // from is lower
        upNeighbour[from] = to;
        downNeighbour[to] = from;
        } // from is lower
      else
        { // to is lower
        upNeighbour[to] = from;
        downNeighbour[from] = to;
        } // to is lower
    } // per vertex
    */
  }
 
}; // SetUpAndDownNeighboursWorklet
 
 
} // namespace bract_maker
} // namespace contourtree_distributed
} // namespace worklet
} // namespace vtkm
 
#endif