\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)
CGAL 4.12.1 - 2D Intersection of Curves
Surface_sweep_2/plane_sweep.cpp
// Computing intersection points among curves using the surface-sweep alg.
#include <list>
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Arr_segment_traits_2.h>
#include <CGAL/Surface_sweep_2_algorithms.h>
typedef Kernel::Point_2 Point_2;
typedef Traits_2::Curve_2 Segment_2;
int main()
{
// Construct the input segments.
Segment_2 segments[] = {Segment_2 (Point_2 (1, 5), Point_2 (8, 5)),
Segment_2 (Point_2 (1, 1), Point_2 (8, 8)),
Segment_2 (Point_2 (3, 1), Point_2 (3, 8)),
Segment_2 (Point_2 (8, 5), Point_2 (8, 8))};
// Compute all intersection points.
std::list<Point_2> pts;
CGAL::compute_intersection_points(segments, segments + 4,
std::back_inserter(pts));
// Print the result.
std::cout << "Found " << pts.size() << " intersection points: " << std::endl;
std::copy(pts.begin(), pts.end(),
std::ostream_iterator<Point_2>(std::cout, "\n"));
// Compute the non-intersecting sub-segments induced by the input segments.
std::list<Segment_2> sub_segs;
CGAL::compute_subcurves(segments, segments + 4, std::back_inserter(sub_segs));
std::cout << "Found " << sub_segs.size()
<< " interior-disjoint sub-segments." << std::endl;
CGAL_assertion(CGAL::do_curves_intersect (segments, segments + 4));
return 0;
}