CGAL 5.4.1 - 2D Arrangements
Arrangement_on_surface_2/generic_curve_data.cpp
// Associating a name attribute with segments using the generic curve-data
// traits.
#include <CGAL/basic.h>
#include <CGAL/Arr_curve_data_traits_2.h>
#include "arr_polylines.h"
typedef std::string Name; // The name-field type.
struct Merge_names {
Name operator() (const Name& s1, const Name& s2) const
{ return (s1 + " " + s2); }
};
Ex_traits;
typedef Ex_traits::Curve_2 Ex_polyline;
typedef Ex_traits::X_monotone_curve_2 Ex_x_monotone_polyline;
typedef CGAL::Arrangement_2<Ex_traits> Ex_arrangement;
int main() {
// Construct an arrangement of four polylines named A--D.
Ex_traits traits;
Ex_arrangement arr(&traits);
auto ctr_curve = traits.construct_curve_2_object();
Point pts1[5] =
{Point(0, 0), Point(2, 4), Point(3, 3), Point(4, 4), Point(6, 0)};
insert(arr, Ex_polyline(ctr_curve(pts1, pts1 + 5), "A"));
Point pts2[3] = {Point(1, 5), Point(3, 3), Point(5, 5)};
insert(arr, Ex_polyline(ctr_curve(pts2, pts2 + 3), "B"));
Point pts3[4] = {Point(1, 0), Point(2, 2), Point(4, 2), Point(5, 0)};
insert(arr, Ex_polyline(ctr_curve(pts3, pts3 + 4), "C"));
Point pts4[2] = {Point(0, 2), Point(6, 2)};
insert(arr, Ex_polyline(ctr_curve(pts4, pts4 + 2), "D"));
// Print all edges that correspond to an overlapping polyline.
std::cout << "The overlapping subcurves:\n";
for (auto eit = arr.edges_begin(); eit != arr.edges_end(); ++eit) {
if (eit->curve().data().length() > 1) {
std::cout << " [" << eit->curve() << "] "
<< "named: " << eit->curve().data() << std::endl;
// Modify the curve associated with the edge.
arr.modify_edge(eit, Ex_x_monotone_polyline(eit->curve(), "overlap"));
}
}
return 0;
}