vtk-m/vtkm/worklet/contourtree/VertexValueComparator.h

//============================================================================
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//  this software.
//============================================================================
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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) {}

  VTKM_EXEC
  bool operator () (const vtkm::Id &i, const vtkm::Id &j, bool ascending)
  {
    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