FindLeaves.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.
 
#ifndef vtkm_worklet_contourtree_find_leaves_h
#define vtkm_worklet_contourtree_find_leaves_h
 
#include <vtkm/filter/scalar_topology/worklet/contourtree/Types.h>
#include <vtkm/worklet/WorkletMapField.h>
 
namespace vtkm
{
namespace worklet
{
namespace contourtree
{
 
// Worklet for doing regular to candidate
class FindLeaves : public vtkm::worklet::WorkletMapField
{
public:
  using ControlSignature = void(FieldIn superID,           // (input) super nodes
                                WholeArrayIn updegree,     // (input)
                                WholeArrayIn downdegree,   // (input)
                                WholeArrayIn joinArc,      // (input)
                                WholeArrayIn splitArc,     // (input)
                                WholeArrayInOut superarc); // (i/o)
  using ExecutionSignature = void(_1, _2, _3, _4, _5, _6);
  using InputDomain = _1;
 
  // Constructor
  VTKM_EXEC_CONT
  FindLeaves() {}
 
  template <typename InPortalFieldType, typename OutPortalFieldType>
  VTKM_EXEC void operator()(const vtkm::Id& superID,
                            const InPortalFieldType& updegree,
                            const InPortalFieldType& downdegree,
                            const InPortalFieldType& joinArc,
                            const InPortalFieldType& splitArc,
                            const OutPortalFieldType& superarc) const
  {
    // omit previously processed vertices
    if (superarc.Get(superID) != NO_VERTEX_ASSIGNED)
      return;
    // Test for extremality - maxima first
    if ((updegree.Get(superID) == 0) && (downdegree.Get(superID) == 1))
    { // maximum
      superarc.Set(superID, joinArc.Get(superID));
    } // maximum
    // minima next
    else if ((updegree.Get(superID) == 1) && (downdegree.Get(superID) == 0))
    { // minimum
      superarc.Set(superID, splitArc.Get(superID));
    } // minimum
  }
}; // FindLeaves
}
}
}
 
#endif