geodesic_algorithm_dijkstra.h

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//Copyright (C) 2008 Danil Kirsanov, MIT License
#ifndef GEODESIC_ALGORITHM_DIJKSTRA_010506
#define GEODESIC_ALGORITHM_DIJKSTRA_010506

#include "geodesic_algorithm_graph_base.h"
#include "geodesic_mesh_elements.h"
#include <vector>
#include <set>
#include <assert.h>

namespace geodesic{

class DijkstraNode
{
  typedef DijkstraNode* node_pointer;
public: 
  DijkstraNode(){};
  ~DijkstraNode(){};

  double& distance_from_source(){return m_distance;};
  node_pointer& previous(){return m_previous;};
  unsigned& source_index(){return m_source_index;};
  vertex_pointer& vertex(){return m_vertex;};

  void clear()
  {
    m_distance = GEODESIC_INF;
    m_previous = NULL;
  }

  bool operator()(node_pointer const s1, node_pointer const s2) const
  {
    return s1->distance_from_source() != s2->distance_from_source() ?
         s1->distance_from_source() < s2->distance_from_source() :
         s1->vertex()->id() < s2->vertex()->id();
  };

  double distance(SurfacePoint* p)
  {
    return m_vertex->distance(p);
  }

  SurfacePoint surface_point()
  {
    return SurfacePoint(m_vertex);
  }

private: 
  double m_distance;          //distance to the closest source
  unsigned m_source_index;      //closest source index
  node_pointer m_previous;      //previous node in the geodesic path
  vertex_pointer m_vertex;      //correspoding vertex
};

class GeodesicAlgorithmDijkstra: public GeodesicAlgorithmGraphBase<DijkstraNode>
{
public:
  typedef DijkstraNode Node;
  typedef Node* node_pointer;

  GeodesicAlgorithmDijkstra(geodesic::Mesh* mesh):
    GeodesicAlgorithmGraphBase<Node>(mesh)
  {
    m_type = DIJKSTRA;

    m_nodes.resize(mesh->vertices().size());
    for(unsigned i=0; i<m_nodes.size(); ++i)
    {
      m_nodes[i].vertex() = &m_mesh->vertices()[i];
    }
  };

  ~GeodesicAlgorithmDijkstra(){};

protected:

  void list_nodes_visible_from_source(MeshElementBase* p,
                    std::vector<node_pointer>& storage);    //list all nodes that belong to this mesh element

  void list_nodes_visible_from_node(node_pointer node,      //list all nodes that belong to this mesh element
                    std::vector<node_pointer>& storage,
                    std::vector<double>& distances,
                    double threshold_distance); //list only the nodes whose current distance is larger than the threshold
};

inline void GeodesicAlgorithmDijkstra::list_nodes_visible_from_source(MeshElementBase* p,
                                 std::vector<node_pointer>& storage)
{
  assert(p->type() != UNDEFINED_POINT);

  if(p->type() == FACE)
  {
    face_pointer f = static_cast<face_pointer>(p);
    for(unsigned i=0; i<3; ++i)
    {
      vertex_pointer v = f->adjacent_vertices()[i];
      storage.push_back(&m_nodes[node_index(v)]);
    }
  }
  else if(p->type() == EDGE)
  {
    edge_pointer e = static_cast<edge_pointer>(p);
    for(unsigned i=0; i<2; ++i)
    {
      vertex_pointer v = e->adjacent_vertices()[i];
      storage.push_back(&m_nodes[node_index(v)]);
    }
  }
  else      //VERTEX
  {
    vertex_pointer v = static_cast<vertex_pointer>(p);
    storage.push_back(&m_nodes[node_index(v)]);
  }
}

inline void GeodesicAlgorithmDijkstra::list_nodes_visible_from_node(node_pointer node, //list all nodes that belong to this mesh element
                               std::vector<node_pointer>& storage,
                               std::vector<double>& distances,
                               double threshold_distance)
{
  vertex_pointer v = node->vertex();
  assert(storage.size() == distances.size());

  for(unsigned i=0; i<v->adjacent_edges().size(); ++i)
  {
    edge_pointer e = v->adjacent_edges()[i];
    vertex_pointer new_v = e->opposite_vertex(v);
    node_pointer new_node = &m_nodes[node_index(new_v)];

    if(new_node->distance_from_source() > threshold_distance + e->length())
    {
      storage.push_back(new_node);
      distances.push_back(e->length());
    }
  }
}

}   //geodesic

#endif //GEODESIC_ALGORITHM_DIJKSTRA_010506