VertexValueComparator.h

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//  This code is based on 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.
 
//=======================================================================================
//
// COMMENTS:
//
// A comparator that sorts vertices by data value, falling back on index to implement
// simulation of simplicity
//
// Any vector needed by the functor for lookup purposes will be passed as a parameter to
// the constructor and saved, with the actual function call being the operator ()
//
//=======================================================================================
 
#ifndef vtkm_worklet_contourtree_vertex_value_comparator_h
#define vtkm_worklet_contourtree_vertex_value_comparator_h
 
#include <vtkm/Types.h>
#include <vtkm/internal/ExportMacros.h>
 
namespace vtkm
{
namespace worklet
{
namespace contourtree
{
 
template <typename InFieldPortalType>
class VertexValueComparator
{
public:
  const InFieldPortalType& values;
 
  VTKM_EXEC_CONT
  VertexValueComparator(const InFieldPortalType& Values)
    : values(Values)
  {
  }
 
  inline VTKM_EXEC bool operator()(const vtkm::Id& i, const vtkm::Id& j, bool ascending) const
  {
    if (values.Get(i) < values.Get(j))
    {
      return ascending ^ true;
    }
    else if (values.Get(j) < values.Get(i))
    {
      return ascending ^ false;
    }
    else if (i < j)
    {
      return ascending ^ true;
    }
    else if (j < i)
    {
      return ascending ^ false;
    }
    // fall through to return false
    return false;
  }
};
}
}
}
 
#endif