\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)

CGAL 4.8 - 2D Arrangements

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Arrangement_on_surface_2/isolated_vertices.cpp
// Constructing an arrangement with isolated vertices.
#include "arr_inexact_construction_segments.h"
#include "arr_print.h"
int main()
{
// Insert isolated points.
Arrangement arr;
Face_handle uf = arr.unbounded_face();
arr.insert_in_face_interior(Point(3, 3), uf);
arr.insert_in_face_interior(Point(1, 5), uf);
arr.insert_in_face_interior(Point(5, 5), uf);
// Insert four segments that form a square-shaped face.
Point p1(1, 3), p2(3, 5), p3(5, 3), p4(3, 1);
Segment s1(p1, p2), s2(p2, p3), s3(p3, p4), s4(p4, p1);
Halfedge_handle e1 = arr.insert_in_face_interior(s1, uf);
Vertex_handle v1 = e1->source();
Vertex_handle v2 = e1->target();
Halfedge_handle e2 = arr.insert_from_left_vertex(s2, v2);
Vertex_handle v3 = e2->target();
Halfedge_handle e3 = arr.insert_from_right_vertex(s3, v3);
Vertex_handle v4 = e3->target();
arr.insert_at_vertices(s4, v4, v1);
// Remove the isolated vertices located in the unbounded face.
Arrangement::Vertex_iterator curr, next = arr.vertices_begin();
for (curr = next++; curr != arr.vertices_end(); curr = next++) {
// Keep an iterator to the next vertex, as curr might be deleted.
if (curr->is_isolated() && curr->face() == uf)
arr.remove_isolated_vertex(curr);
}
print_arrangement(arr);
return 0;
}