CGAL 6.1.1 - 2D Arrangements

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Arrangement_on_surface_2/dcel_extension.cpp
// Extending all DCEL records (vertices, edges and faces).
#include <CGAL/Arr_extended_dcel.h>
#include "arr_exact_construction_segments.h"
enum Color {BLUE, RED, WHITE};
using Dcel = CGAL::Arr_extended_dcel<Traits, Color, bool, size_t>;
using Ex_arrangement = CGAL::Arrangement_2<Traits, Dcel>;
int main() {
// Construct the arrangement containing two intersecting triangles.
Traits traits;
Ex_arrangement arr(&traits);
insert_non_intersecting_curve(arr, Segment(Point(4, 1), Point(7, 6)));
insert_non_intersecting_curve(arr, Segment(Point(1, 6), Point(7, 6)));
insert_non_intersecting_curve(arr, Segment(Point(4, 1), Point(1, 6)));
insert(arr, Segment(Point(1, 3), Point(7, 3)));
insert(arr, Segment(Point(1, 3), Point(4, 8)));
insert(arr, Segment(Point(4, 8), Point(7, 3)));
insert_point(arr, Point(4, 4.5));
// Go over all arrangement edges and set their flags.
// Recall that the value type of the edge iterator is the halfedge type.
for (auto vit = arr.vertices_begin(); vit != arr.vertices_end(); ++vit) {
auto degree = vit->degree();
vit->set_data((degree == 0) ? BLUE : ((degree <= 2) ? RED : WHITE));
}
auto equal = traits.equal_2_object();
for (auto eit = arr.edges_begin(); eit != arr.edges_end(); ++eit) {
// Check whether the halfedge has the same direction as its segment.
bool flag = equal(eit->source()->point(),eit->curve().source());
eit->set_data(flag);
eit->twin()->set_data(!flag);
}
// Store the size of the outer boundary of every face of the arrangement.
for (auto fit = arr.faces_begin(); fit != arr.faces_end(); ++fit) {
size_t boundary_size = 0;
if (! fit->is_unbounded()) {
Ex_arrangement::Ccb_halfedge_circulator curr = fit->outer_ccb();
boundary_size = std::distance(++curr, fit->outer_ccb())+1;
}
fit->set_data(boundary_size);
}
// Copy the arrangement and print the vertices along with their colors.
Ex_arrangement arr2 = arr;
std::cout << "The arrangement vertices:\n";
for (auto vit = arr2.vertices_begin(); vit != arr2.vertices_end(); ++vit) {
std::cout << '(' << vit->point() << ") - ";
switch (vit->data()) {
case BLUE : std::cout << "BLUE.\n"; break;
case RED : std::cout << "RED.\n"; break;
case WHITE : std::cout << "WHITE.\n"; break;
}
}
std::cout << "The arrangement outer-boundary sizes:";
for (auto fit = arr2.faces_begin(); fit != arr2.faces_end(); ++fit)
std::cout << " " << fit->data();
std::cout << std::endl;
return 0;
}
CGAL::Arr_extended_dcel
The Arr_extended_dcel class-template extends the topological-features of the DCEL namely the vertex,...
Definition: Arr_extended_dcel.h:43
CGAL::Arrangement_2
Definition: Arrangement_2.h:57