KDTree.h

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//* This file is part of the MOOSE framework
//* https://mooseframework.inl.gov
//*
//* All rights reserved, see COPYRIGHT for full restrictions
//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
//*
//* Licensed under LGPL 2.1, please see LICENSE for details
//* https://www.gnu.org/licenses/lgpl-2.1.html
 
#pragma once
 
// Moose includes
#include "MooseMesh.h"
#include "PointListAdaptor.h"
 
#include "libmesh/nanoflann.hpp"
#include "libmesh/utility.h"
 
// Make newer nanoflann API compatible with older nanoflann versions
#if NANOFLANN_VERSION < 0x150
namespace nanoflann
{
template <typename T, typename U>
using ResultItem = std::pair<T, U>;
}
#endif
 
class KDTree
{
public:
  KDTree(const std::vector<Point> & master_points, unsigned int max_leaf_size);
 
  virtual ~KDTree() = default;
 
  void neighborSearch(const Point & query_point,
                      unsigned int patch_size,
                      std::vector<std::size_t> & return_index);
 
  void neighborSearch(const Point & query_point,
                      unsigned int patch_size,
                      std::vector<std::size_t> & return_index,
                      std::vector<Real> & return_dist_sqr);
 
  void radiusSearch(const Point & query_point,
                    Real radius,
                    std::vector<nanoflann::ResultItem<std::size_t, Real>> & indices_dist);
 
  std::size_t numberCandidatePoints();
 
  using KdTreeT = nanoflann::KDTreeSingleIndexAdaptor<
      nanoflann::L2_Simple_Adaptor<Real,
                                   /* DataSource = */ PointListAdaptor<Point>,
                                   /* DistanceType = */ Real,
                                   /* AccessorType = */ std::size_t>,
      PointListAdaptor<Point>,
      LIBMESH_DIM,
      std::size_t>;
 
protected:
  PointListAdaptor<Point> _point_list_adaptor;
  std::unique_ptr<KdTreeT> _kd_tree;
};