[英]Voronoi Diagram using CGAL: extract only edge points (convex hull)
I want to extract edge points (points lie on an edge of the boundary of the convex hull) using Voronoi diagram. 我想使用Voronoi图提取边缘点(点位于凸包边界的边缘)。 I know that an unbounded cell contains a boundary site point, but how can I access to that information using iterators?
我知道无界单元格包含边界站点,但是如何使用迭代器访问该信息呢?
Solution 解
VD vd;
//initialise your voronoi diagram
VD::Face_iterator it = vd.faces_begin(), beyond = vd.faces_end();
for (int f = 0; it != beyond; ++f, ++it)
{
std::cout << "Face " << f << ": \n";
if (it->is_unbounded())
{
// it's a boundary point
}
}
Read CGAL 2D Delaunay Triangulation: How to get edges as vertex id pairs , and having in mind the relation between Voronoi and Delaunay check this example : 阅读CGAL 2D Delaunay三角剖分:如何将边缘作为顶点id对 ,并考虑到Voronoi和Delaunay之间的关系,请检查此示例 :
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Delaunay_triangulation_2.h>
#include <fstream>
typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Delaunay_triangulation_2<K> Triangulation;
typedef Triangulation::Edge_iterator Edge_iterator;
typedef Triangulation::Point Point;
int main( )
{
std::ifstream in("data/voronoi.cin");
std::istream_iterator<Point> begin(in);
std::istream_iterator<Point> end;
Triangulation T;
T.insert(begin, end);
int ns = 0;
int nr = 0;
Edge_iterator eit =T.edges_begin();
for ( ; eit !=T.edges_end(); ++eit) {
CGAL::Object o = T.dual(eit);
if (CGAL::object_cast<K::Segment_2>(&o)) {++ns;}
else if (CGAL::object_cast<K::Ray_2>(&o)) {++nr;}
}
std::cout << "The Voronoi diagram has " << ns << " finite edges "
<< " and " << nr << " rays" << std::endl;
return 0;
}
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