CGAL - 在Delaunay三角剖分后檢索頂點索引

Question

我正在計算幾千點的2D delaunay三角剖分。 每個點都有超過x和y坐標的更多數據。 因此，我想知道是否有可能檢索每個點的索引，以便我可以在另一個向量中訪問我自己的點結構。

目前，當我從Face_handle訪問頂點時，它返回一個點（即x，y坐標）如何通過其ID（索引）而不是其x，y坐標返回每個頂點？ 謝謝。

#include <vector>
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Delaunay_triangulation_2.h>

typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef CGAL::Delaunay_triangulation_2<Kernel> Delaunay;
typedef Kernel::Point_2 Point;

void example() {

  std::vector<Point> points;
  points.push_back(Point(1,1)); //index 0
  points.push_back(Point(1,2)); //index 1
  points.push_back(Point(1,3)); //index 2
  points.push_back(Point(2,1)); //index 3
  points.push_back(Point(2,2)); //index 4
  points.push_back(Point(2,3)); //index 5

  Delaunay triangulation;
  triangulation.insert(points.begin(),points.end());

  for(Delaunay::Finite_faces_iterator fit = triangulation.finite_faces_begin();
      fit != triangulation.finite_faces_end(); ++fit) {

    Delaunay::Face_handle face = fit;
    std::cout << "Triangle:\t" << triangulation.triangle(face) << std::endl;
    std::cout << "Vertex 0:\t" << triangulation.triangle(face)[0] << std::endl;
  }
}

輸出（x，y坐標）：

Triangle:   1 3 1 2 2 2
Vertex 0:   1 3
Triangle:   1 2 1 1 2 1
Vertex 0:   1 2
Triangle:   1 3 2 2 2 3
Vertex 0:   1 3
Triangle:   1 2 2 1 2 2
Vertex 0:   1 2

期望的產出（指數）：

Triangle:   2   1   4
Vertex 0:   2
Triangle:   1   0   3
Vertex 0:   1 
Triangle:   2   4   5
Vertex 0:   2
Triangle:   1   3   4
Vertex 0:   1

Answer 1

您可以將任何信息附加到三角測量中的頂點。 例如，要添加索引（ unsigned int ），您可以執行以下操作：

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Delaunay_triangulation_2.h>
#include <CGAL/Triangulation_vertex_base_with_info_2.h>
#include <vector>

typedef CGAL::Exact_predicates_inexact_constructions_kernel            Kernel;
typedef CGAL::Triangulation_vertex_base_with_info_2<unsigned int, Kernel> Vb;
typedef CGAL::Triangulation_data_structure_2<Vb>                       Tds;
typedef CGAL::Delaunay_triangulation_2<Kernel, Tds>                    Delaunay;
typedef Kernel::Point_2                                                Point;

int main() {

  std::vector< std::pair<Point,unsigned> > points;
  points.push_back( std::make_pair( Point(1,1), 0 ) );
  points.push_back( std::make_pair( Point(1,2), 1 ) );
  points.push_back( std::make_pair( Point(1,3), 2 ) );
  points.push_back( std::make_pair( Point(2,1), 3 ) );
  points.push_back( std::make_pair( Point(2,2), 4 ) );
  points.push_back( std::make_pair( Point(2,3), 5 ) );

  Delaunay triangulation;
  triangulation.insert(points.begin(),points.end());

  for(Delaunay::Finite_faces_iterator fit = triangulation.finite_faces_begin();
      fit != triangulation.finite_faces_end(); ++fit) {

    Delaunay::Face_handle face = fit;
    std::cout << "Triangle:\t" << triangulation.triangle(face) << std::endl;
    std::cout << "Vertex 0:\t" << triangulation.triangle(face)[0] << std::endl;
    std::cout << "Vertex 0:\t" << face->vertex(0)->info() << std::endl;
  }
}