Surface_sweep_2/plane_sweep.cpp

 
// Computing intersection points among curves using the surface-sweep alg.
 
#include <list>
#include <cassert>
 
#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Arr_segment_traits_2.h>
#include <CGAL/Surface_sweep_2_algorithms.h>
 
using Kernel = CGAL::Exact_predicates_exact_constructions_kernel;
using Point_2 = Kernel::Point_2;
using Traits_2 = CGAL::Arr_segment_traits_2<Kernel>;
using Segment_2 = Traits_2::Curve_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;
  assert(CGAL::Surface_sweep_2::do_intersect(segments, segments + 4, false));
 
  return 0;
}