Fixed removal of unbounded & added corresponding tests

Arrangement_on_surface_2/include/CGAL/Arrangement_2/Arrangement_on_surface_2_impl.h

@@ -3801,12 +3801,16 @@ _is_smaller(const DHalfedge* he1,
   CGAL_precondition(he2->direction() == ARR_RIGHT_TO_LEFT);
   CGAL_precondition(he1->vertex() != he2->vertex());
 
-  // If he1 points to the bottom left vertex, then it is the smaller.
+  /* If he1 points to a vertex on the left or the bottom boundary, then it
-  if ((ps_x1 == ARR_LEFT_BOUNDARY) && (ps_y1 == ARR_BOTTOM_BOUNDARY))
+   * is the smaller.
+   */
+  if ((ps_x1 == ARR_LEFT_BOUNDARY) || (ps_y1 == ARR_BOTTOM_BOUNDARY))
     return true;
 
-  // If he2 points to the bottom left vertex, then it is the smaller.
+  /* If he2 points to a vertex on the left or the bottom boundary, then it
-  if ((ps_x2 == ARR_LEFT_BOUNDARY) && (ps_y2 == ARR_BOTTOM_BOUNDARY))
+   * is the smaller.
+   */
+  if ((ps_x2 == ARR_LEFT_BOUNDARY) || (ps_y2 == ARR_BOTTOM_BOUNDARY))
     return false;
 
   return _is_smaller(he1->curve(), he1->vertex()->point(), ps_x1, ps_y1,

Arrangement_on_surface_2/test/Arrangement_on_surface_2/test_unbounded_removal.cpp

@@ -18,10 +18,49 @@ typedef Traits_2::Line_2                                Line_2;
 typedef Traits_2::X_monotone_curve_2                    X_monotone_curve_2;
 typedef CGAL::Arrangement_2<Traits_2>                   Arrangement_2;
 typedef Arrangement_2::Vertex_handle                    Vertex_handle;
+typedef Arrangement_2::Face_handle                      Face_handle;
 typedef Arrangement_2::Halfedge_handle                  Halfedge_handle;
 
+bool test(const Arrangement_2& arr)
+{
+  if (arr.number_of_vertices() != 0) {
+    std::cerr << "(A) Number of vertices (" << arr.number_of_vertices()
+              << ") not 0!" << std::endl;
+    return false;
+  }
+
+  // Check the validity more thoroughly.
+  if (! CGAL::is_valid(arr)) {
+    std::cerr << "The arrangement is NOT valid!" << std::endl;
+    return false;
+  }
+
+  return true;
+}
+
+bool test_ray(Arrangement_2& arr, Face_handle f)
+{
+  Segment_2 s1(Point_2(0, 0), Point_2(1, 0));
+  Halfedge_handle eh1 =
+    arr.insert_in_face_interior(X_monotone_curve_2(s1), f);
+  Vertex_handle vh = eh1->target();
+  Ray_2 ray(Point_2(1, 0), Point_2(2, 0));
+  Halfedge_handle eh2 =
+    arr.insert_from_left_vertex(X_monotone_curve_2(ray), vh);
+
+  // Remove the edges
+  arr.remove_edge(eh2);
+  arr.remove_edge(eh1);
+
+  if (!test(arr)) return false;
+
+  return true;
+}
+
 int main()
 {
+  Arrangement_2 arr;
+
   // Construct an arrangement of five linear objects.
   std::vector<X_monotone_curve_2>  curves;
   curves.push_back(Ray_2(Point_2(0, 0), Point_2(0, 1)));
@@ -33,7 +72,6 @@ int main()
   curves.push_back(Ray_2(Point_2(0, 0), Point_2(-1, 1)));
   curves.push_back(Ray_2(Point_2(0, 0), Point_2(-1, -1)));
 
-  Arrangement_2 arr;
   std::vector<Halfedge_handle> hhs(curves.size());
   for (size_t i = 0; i < curves.size(); i++)
     hhs[i] = insert_non_intersecting_curve(arr, curves[i]);
@@ -61,42 +99,63 @@ int main()
             << ",  E = " << arr.number_of_edges()
             << ",  F = " << arr.number_of_faces() << std::endl;
 
-  if (arr.number_of_vertices() != 0) {
+  if (!test(arr)) return 1;
-    std::cerr << "(A) Number of vertices (" << arr.number_of_vertices()
-              << ") not 0!" << std::endl;
-    return 1;
-  }
 
-  // Check the validity more thoroughly.
+  /* Construct another arrangement of a segment connected to a ray.
-  if (! CGAL::is_valid(arr)) {
+   * First remove the ray, then remove the segment.
-    std::cerr << "The arrangement is NOT valid!" << std::endl;
+   *
-    return 1;
+   *  o---------------o
-  }
+   *  |               |
+   *  |               |
+   *  |               |
+   *  |       o--o----|
+   *  |               |
+   *  |               |
+   *  |               |
+   *  o---------------o
+   */
+  if (!test_ray(arr, arr.unbounded_face())) return 1;
 
-  // Construct another arrangement of a segment connected to a ray
+  /* Construct another arrangement of a segment connected to a ray.
-  Segment_2 s1(Point_2(0, 0), Point_2(1, 1));
+   * First remove the ray, then remove the segment.
+   *
+   *  o---------------o
+   *  |               |
+   *  |               |
+   *  |               |
+   *  |       o--o----|
+   *  |               |
+   *  o---------------o
+   *  |               |
+   *  o---------------o
+   */
+  Line_2 l1(Point_2(0, -1), Point_2(1, -1));
   Halfedge_handle eh1 =
-    arr.insert_in_face_interior(X_monotone_curve_2(s1), arr.unbounded_face());
+    arr.insert_in_face_interior(X_monotone_curve_2(l1), arr.unbounded_face());
-  Vertex_handle vh = eh1->target();
-  Ray_2 ray(Point_2(1, 1), Point_2(2, 2));
-  Halfedge_handle eh2 =
-    arr.insert_from_left_vertex(X_monotone_curve_2(ray), vh);
 
-  // Remove the edges
+  if (!test_ray(arr, eh1->face())) return 1;
-  arr.remove_edge(eh2);
   arr.remove_edge(eh1);
 
-  if (arr.number_of_vertices() != 0) {
+  /* Construct another arrangement of a segment connected to a ray.
-    std::cerr << "(B) Number of vertices (" << arr.number_of_vertices()
+   * First remove the ray, then remove the segment.
-              << ") not 0!" << std::endl;
+   *
-    return 1;
+   *  o-----o---------o
-  }
+   *  |     |         |
+   *  |     |         |
+   *  |     |         |
+   *  |     | o--o----|
+   *  |     |         |
+   *  |     |         |
+   *  |     |         |
+   *  o-----o---------o
+   */
+  Line_2 l2(Point_2(-1, 0), Point_2(-1, 1));
+  Halfedge_handle eh2 =
+    arr.insert_in_face_interior(X_monotone_curve_2(l2), arr.unbounded_face());
 
-  if (! CGAL::is_valid(arr)) {
+  if (!test_ray(arr, eh2->twin()->face())) return 1;
-    std::cerr << "The arrangement is NOT valid!" << std::endl;
+  arr.remove_edge(eh2);
-    return 1;
-  }
 
-  return (0);
+  return 0;
 }