void CroftonTessellation::remove_internal_lines() {
/* Remove all curves except the boundary curves from the
tessellation. BE CAUTIOUS: removing internal lines does not
remove vertices along the boundary. */
CroftonTessellation::Curve_iterator c1,c2;
c1 = curve_node_begin();
c1++;c1++;c1++;c1++;
c2 = curve_node_end();
while(c1!=c2)
remove_curve(c1++);
}
int main ()
{
// Construct an arrangement containing nine circles: C[0] of radius 2 and
// C[1], ..., C[8] of radius 1.
const Number_type _7_halves = Number_type (7, 2);
Arr_with_hist_2 arr;
Curve_2 C[9];
Curve_handle handles[9];
int k;
C[0] = Circle_2 (Rat_point_2 (_7_halves, _7_halves), 4, CGAL::CLOCKWISE);
C[1] = Circle_2 (Rat_point_2 (_7_halves, 6), 1, CGAL::CLOCKWISE);
C[2] = Circle_2 (Rat_point_2 (5, 6), 1, CGAL::CLOCKWISE);
C[3] = Circle_2 (Rat_point_2 (6, _7_halves), 1, CGAL::CLOCKWISE);
C[4] = Circle_2 (Rat_point_2 (5, 2), 1, CGAL::CLOCKWISE);
C[5] = Circle_2 (Rat_point_2 (_7_halves, 1), 1, CGAL::CLOCKWISE);
C[6] = Circle_2 (Rat_point_2 (2, 2), 1, CGAL::CLOCKWISE);
C[7] = Circle_2 (Rat_point_2 (1, _7_halves), 1, CGAL::CLOCKWISE);
C[8] = Circle_2 (Rat_point_2 (2, 5), 1, CGAL::CLOCKWISE);
for (k = 0; k < 9; k++)
handles[k] = insert (arr, C[k]);
std::cout << "The initial arrangement size:" << std::endl
<< " V = " << arr.number_of_vertices()
<< ", E = " << arr.number_of_edges()
<< ", F = " << arr.number_of_faces() << std::endl;
// Remove the large circle C[0].
std::cout << "Removing C[0] : ";
std::cout << remove_curve (arr, handles[0])
<< " edges have been removed." << std::endl;
std::cout << "The arrangement size:" << std::endl
<< " V = " << arr.number_of_vertices()
<< ", E = " << arr.number_of_edges()
<< ", F = " << arr.number_of_faces() << std::endl;
// Locate the point q, which should be on an edge e.
Point_location pl (arr);
const Point_2 q = Point_2 (_7_halves, 7);
CGAL::Object obj = pl.locate (q);
Arr_with_hist_2::Halfedge_const_handle e;
CGAL_assertion_code(bool success = ) CGAL::assign (e, obj);
CGAL_assertion (success);
// Split the edge e to two edges e1 and e2;
Arr_with_hist_2::Halfedge_handle e1, e2;
e1 = arr.split_edge (arr.non_const_handle (e), q);
e2 = e1->next();
std::cout << "After edge split: "
<< "V = " << arr.number_of_vertices()
<< ", E = " << arr.number_of_edges()
<< ", F = " << arr.number_of_faces() << std::endl;
// Merge back the two split edges.
arr.merge_edge (e1, e2);
std::cout << "After edge merge: "
<< "V = " << arr.number_of_vertices()
<< ", E = " << arr.number_of_edges()
<< ", F = " << arr.number_of_faces() << std::endl;
return 0;
}