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//! \file examples/Arrangement_on_surface_2/vertical_decomposition.cpp
// Performing vertical decomposition of an arrangement.
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Arr_segment_traits_2.h>
#include <CGAL/Arrangement_2.h>
#include <CGAL/Arr_vertical_decomposition_2.h>
#include <list>
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef CGAL::Arr_segment_traits_2<Kernel> Traits_2;
typedef Traits_2::Point_2 Point_2;
typedef Traits_2::X_monotone_curve_2 Segment_2;
typedef CGAL::Arrangement_2<Traits_2> Arrangement_2;
typedef Arrangement_2::Vertex_const_handle Vertex_const_handle;
typedef Arrangement_2::Halfedge_const_handle Halfedge_const_handle;
typedef Arrangement_2::Face_const_handle Face_const_handle;
typedef std::pair<CGAL::Object, CGAL::Object> Object_pair;
typedef std::pair<Vertex_const_handle, Object_pair> Vert_decomp_entry;
typedef std::list<Vert_decomp_entry> Vert_decomp_list;
int main()
{
// Construct the arrangement.
Arrangement_2 arr;
insert_non_intersecting_curve(arr, Segment_2(Point_2(1, 1), Point_2(3, 0)));
insert_non_intersecting_curve(arr, Segment_2(Point_2(1, 1), Point_2(2, 2)));
insert_non_intersecting_curve(arr, Segment_2(Point_2(2, 2), Point_2(3, 0)));
insert_non_intersecting_curve(arr, Segment_2(Point_2(2, 2), Point_2(5, 0)));
insert_non_intersecting_curve(arr, Segment_2(Point_2(3, 2), Point_2(5, 0)));
insert_non_intersecting_curve(arr, Segment_2(Point_2(2, 3), Point_2(3, 3)));
insert_non_intersecting_curve(arr, Segment_2(Point_2(0, 3), Point_2(6, 4)));
insert_non_intersecting_curve(arr, Segment_2(Point_2(4, 4), Point_2(4, 5)));
// Perform vertical ray-shooting from every vertex and locate the feature
// that lie below it and the feature that lies above it.
Vert_decomp_list vd_list;
CGAL::decompose(arr, std::back_inserter(vd_list));
// Print the results.
Vert_decomp_list::const_iterator vd_iter;
for (vd_iter = vd_list.begin(); vd_iter != vd_list.end(); ++vd_iter) {
const Object_pair& curr = vd_iter->second;
std::cout << "Vertex (" << vd_iter->first->point() << ") : ";
Vertex_const_handle vh;
Halfedge_const_handle hh;
Face_const_handle fh;
std::cout << " feature below: ";
if (CGAL::assign(hh, curr.first))
std::cout << '[' << hh->curve() << ']';
else if (CGAL::assign(vh, curr.first))
std::cout << '(' << vh->point() << ')';
else if (CGAL::assign(fh, curr.first))
std::cout << "NONE";
else
std::cout << "EMPTY";
std::cout << " feature above: ";
if (CGAL::assign(hh, curr.second))
std::cout << '[' << hh->curve() << ']' << std::endl;
else if (CGAL::assign(vh, curr.second))
std::cout << '(' << vh->point() << ')' << std::endl;
else if (CGAL::assign(fh, curr.second))
std::cout << "NONE" << std::endl;
else
std::cout << "EMPTY" << std::endl;
}
return 0;
}
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