CGAL users discussion list

[phygeeks <>]

Hi, I installed CGAL 4.6.1 and ran the following code:
====
// Computing intersection points among curves using the sweep line.
#include <CGAL/Cartesian.h>
#include <CGAL/Arr_segment_traits_2.h>
#include <CGAL/Arr_polyline_traits_2.h>
#include <CGAL/Sweep_line_2_algorithms.h>
#include <vector>
#include <list>

#include "cgal_intersection.h"

typedef CGAL::Cartesian<double>                         Kernel;
typedef CGAL::Arr_segment_traits_2<Kernel>              Segment_traits;
typedef CGAL::Arr_polyline_traits_2<Segment_traits>     Polyline_traits;
typedef Polyline_traits::Point_2                        Point;
typedef Polyline_traits::Curve_2                        Polyline;

//extern "C" int find_intersections_of_curves(
int find_intersections_of_curves(
    coordinate *curve_1, long curve_1_size,
    coordinate *curve_2, long curve_2_size,
    coordinate *intersections, int max_num_of_intersections)
{
    Polyline_traits polyline_traits;
    Polyline_traits::Construct_curve_2 construct_polyline =
        polyline_traits.construct_curve_2_object();

    int num_of_curves = 2;
    coordinate *curves[] = {curve_1, curve_2};
    long size_of_curve[] = {curve_1_size, curve_2_size};
    std::vector<Polyline> polylines;

    std::cout << "Construct polylines.\n";

    for(int n = 0; n < num_of_curves; n++){
        std::vector<Point> points;
        Point p_0 = Point(curves[n][0].x, curves[n][0].y);
        points.push_back(p_0);
        for(long i = 1; i < size_of_curve[n]; i++){
            Point p_i = Point(curves[n][i].x, curves[n][i].y);
            if(p_i != points.back()){
                points.push_back(p_i);
            }
        }
        polylines.push_back(construct_polyline(points.begin(),
points.end()));
    }

    std::cout << "Compute intersection points.\n";
    std::list<Point> intersection_points;
    CGAL::compute_intersection_points(polylines.begin(), polylines.end(),
                                     
std::back_inserter(intersection_points),
                                      false, polyline_traits);

    int num_of_intersections = intersection_points.size();
    Point intersection_point;
    std::cout << "Prepare intersection points.\n";
    for (int j = 0; j < num_of_intersections; j++){
        if (j == max_num_of_intersections)
            break;
        intersection_point = intersection_points.front();
        intersections[j].x = intersection_point.x();
        intersections[j].y = intersection_point.y();
        intersection_points.pop_front();
    }

    return num_of_intersections;
}

int main(void){
    coordinate c11 = {0.0, 0.0};
    coordinate c12 = {1.0, 1.0};
    coordinate curve_1[2] = {c11, c12};

    coordinate c21 = {0.0, 1.0};
    coordinate c22 = {1.0, 0.0};
    coordinate curve_2[2] = {c21, c22};

    coordinate intersections[1];

    std::cout << "Find an intersection using CGAL.\n";

    find_intersections_of_curves(curve_1, 2, curve_2, 2, intersections, 1);

    std::cout << intersections[0].x << ", " << intersections[0].y << '\n';
}
====
When I run it, I get the following result:
====
Find an intersection using CGAL.
Construct polylines.
Compute intersection points.


Prepare intersection points.
0.5, 0.5
====
As you can see, when compute_intersection_points() is invoked, somehow it
prints out two new lines. This interferes with my logging file so I want to
remove it. Could you tell me what is the problem here?



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