tree_node.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2026 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 
 
#ifndef LIBMESH_TREE_NODE_H
#define LIBMESH_TREE_NODE_H
 
// Local includes
#include "libmesh/libmesh_common.h"
#include "libmesh/bounding_box.h"
#include "libmesh/point.h"
 
// C++ includes
#include <cstddef>
#include <set>
#include <unordered_map>
#include <vector>
#include <memory>
 
namespace libMesh
{
 
// Forward Declarations
class MeshBase;
class Node;
class Elem;
 
template <unsigned int N>
class TreeNode
{
public:
  TreeNode (const MeshBase & m,
            unsigned int tbs,
            const TreeNode<N> * p = nullptr);
 
  TreeNode (const TreeNode<N> &) = delete;
 
  ~TreeNode () = default;
 
  bool is_root() const { return (parent == nullptr); }
 
  bool active() const { return children.empty(); }
 
  bool insert (const Node * nd);
 
  bool insert (const Elem * nd);
 
  void refine ();
 
  void set_bounding_box (const std::pair<Point, Point> & bbox);
 
  bool bounds_node (const Node * nd,
                    Real relative_tol = 0) const;
 
  bool bounds_point (const Point & p,
                     Real relative_tol = 0) const;
 
  unsigned int level () const;
 
  void print_nodes(std::ostream & out_stream=libMesh::out) const;
 
  void print_elements(std::ostream & out_stream=libMesh::out) const;
 
  void transform_nodes_to_elements (std::vector<std::vector<const Elem *>> & nodes_to_elem);
 
  void transform_nodes_to_elements (std::unordered_map<dof_id_type, std::vector<const Elem *>> & nodes_to_elem);
 
  unsigned int n_active_bins() const;
 
  const Elem * find_element (const Point & p,
                             const std::set<subdomain_id_type> * allowed_subdomains = nullptr,
                             Real relative_tol = TOLERANCE) const;
 
  void find_elements (const Point & p,
                      std::set<const Elem *> & candidate_elements,
                      const std::set<subdomain_id_type> * allowed_subdomains = nullptr,
                      Real relative_tol = TOLERANCE) const;
 
private:
  const Elem * find_element_in_children (const Point & p,
                                         const std::set<subdomain_id_type> * allowed_subdomains,
                                         Real relative_tol) const;
 
  void find_elements_in_children (const Point & p,
                                  std::set<const Elem *> & candidate_elements,
                                  const std::set<subdomain_id_type> * allowed_subdomains,
                                  Real relative_tol) const;
 
  BoundingBox create_bounding_box (unsigned int c) const;
 
  const MeshBase & mesh;
 
  const TreeNode<N> * parent;
 
  std::vector<std::unique_ptr<TreeNode<N>>> children;
 
  BoundingBox bounding_box;
 
  std::vector<const Elem *> elements;
 
  std::vector<const Node *> nodes;
 
  const unsigned int tgt_bin_size;
 
  unsigned int target_bin_size_increase_level;
 
  bool contains_ifems;
};
 
 
 
 
 
// ------------------------------------------------------------
// TreeNode class inline methods
template <unsigned int N>
inline
TreeNode<N>::TreeNode (const MeshBase & m,
                       unsigned int tbs,
                       const TreeNode<N> * p) :
  mesh           (m),
  parent         (p),
  tgt_bin_size   (tbs),
  target_bin_size_increase_level(10),
  contains_ifems (false)
{
  // libmesh_assert our children are empty, thus we are active.
  libmesh_assert (children.empty());
  libmesh_assert (this->active());
 
  // Reserve space for the nodes & elements
  nodes.reserve    (tgt_bin_size);
  elements.reserve (tgt_bin_size);
}
 
 
 
template <unsigned int N>
inline
unsigned int TreeNode<N>::level () const
{
  if (parent != nullptr)
    return parent->level()+1;
 
  // if we have no parent, we are a level-0 box
  return 0;
}
 
 
} // namespace libMesh
 
 
#endif // LIBMESH_TREE_NODE_H