ArrangementPointLocation_2 Concept Reference

Definition

A model of the ArrangementPointLocation_2 concept can answer point-location queries on an arrangement attached to it. Namely, given a Arrangement_2::Point_2 object, representing a point in the plane, it returns the arrangement cell containing it. In the general case, the query point is contained inside an arrangement face, but in degenerate situations it may lie on an edge or coincide with an arrangement vertex.

A note on Backwards compatibility
The locate member function used to return CGAL::Object up to CGAL version 4.2. Starting with CGAL version 4.3 the return type is determined by a metafunction. To preserve backwards compatibility CGAL::Object can be constructed from the new return types implicitly, but switching to the new style is recommended. To enable the old style without any overhead, the macro CGAL_ARR_POINT_LOCATION_VERSION can be defined to 1 before any CGAL header is included.

Has Models:

CGAL::Arr_naive_point_location<Arrangement>

CGAL::Arr_walk_along_line_point_location<Arrangement>

CGAL::Arr_trapezoid_ric_point_location<Arrangement>

CGAL::Arr_landmarks_point_location<Arrangement,Generator>

See Also

CGAL::Arr_naive_point_location<Arrangement>

CGAL::Arr_walk_along_line_point_location<Arrangement>

CGAL::Arr_trapezoid_ric_point_location<Arrangement>

CGAL::Arr_landmarks_point_location<Arrangement,Generator>

CGAL::Arr_point_location_result<Arrangement>

CGAL_ARR_POINT_LOCATION_VERSION

Types
typedef unspecified_type	Arrangement_2
	the associated arrangement type.
typedef unspecified_type	Point_2
	equivalent to Arrangement_2::Point_2.

Creation
	ArrangementPointLocation_2 ()
	default constructor.
	ArrangementPointLocation_2 (const Arrangement_2 &arr)
	constructs a point-location object pl attached to the given arrangement arr.

Query Functions
Arr_point_location_result < Arrangement_2 >::Type	locate (const Point_2 &q) const
	locates the arrangement cell that contains the query point q and returns a discriminated union container of the following bounded types: More...

Operations
void	attach (const Arrangement_2 &arr)
	attaches pl to the given arrangement arr.
void	detach ()
	detaches pl from the arrangement it is currently attached to.

Member Function Documentation

Arr_point_location_result<Arrangement_2>::Type ArrangementPointLocation_2::locate

(

const Point_2 &

q)

const

locates the arrangement cell that contains the query point q and returns a discriminated union container of the following bounded types:

• Arrangement_2::Face_const_handle, in case q is contained inside an arrangement face;
• Arrangement_2::Halfedge_const_handle, in case q lies on an arrangement edge;
• Arrangement_2::Vertex_const_handle, in case q coincides with an arrangement vertex.

Precondition

pl is attached to a valid arrangement object.