ArrangementVerticalRayShoot_2 Concept Reference

Definition

A model of the ArrangementVerticalRayShoot_2 concept can answer vertical ray-shooting 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 feature (edge or vertex) that lies strictly above it (or below it). By "strictly" we mean that if the query point lies on an arrangement edge (or on an arrangement vertex) this edge will not be the query result, but the feature lying above or below it. (An exception to this rule is the degenerate case where the query point lies in the interior of a vertical edge.) Note that it may happen that the query point lies above the upper envelope (or below the lower envelope) of the arrangement, and the vertical ray emanating from the query point goes to infinity without hitting any arrangement feature on its way. In this case the unbounded face is returned.

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>

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

Creation
	ArrangementVerticalRayShoot_2 ()
	default constructor.
	ArrangementVerticalRayShoot_2 (const Arrangement_2 &arr)
	constructs a ray-shooting object rs attached to the given arrangement arr.

Query Functions
Arr_point_location_result< Arrangement_2 >::Type	ray_shoot_up (const Point_2 &q) const
	locates the arrangement feature that is first hit by an upward-directed vertical ray emanating from the query point q, and returns a handle for this feature.
Arr_point_location_result< Arrangement_2 >::Type	ray_shoot_down (const Point_2 &q) const
	locates the arrangement feature that is first hit by a downward-directed vertical ray emanating from the query point q, and returns a handle for this feature.

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

Member Function Documentation

ray_shoot_down()

Arr_point_location_result< Arrangement_2 >::Type ArrangementVerticalRayShoot_2::ray_shoot_down

(

const Point_2 &

q

)

const

locates the arrangement feature that is first hit by a downward-directed vertical ray emanating from the query point q, and returns a handle for this feature.

The function returns a discriminated union container of the following bounded types:

• Arrangement_2::Halfedge_const_handle, in case the vertical ray hits an arrangement edge;
• Arrangement_2::Vertex_const_handle, in case the vertical ray hits an arrangement vertex.
• Arrangement_2::Face_const_handle for the unbounded arrangement face, in case q lies below the lower envelope of the arrangement.

Precondition

rs is attached to a valid arrangement instance.

ray_shoot_up()

Arr_point_location_result< Arrangement_2 >::Type ArrangementVerticalRayShoot_2::ray_shoot_up

(

const Point_2 &

q

)

const

locates the arrangement feature that is first hit by an upward-directed vertical ray emanating from the query point q, and returns a handle for this feature.

The function returns a discriminated union container of the following bounded types:

• Arrangement_2::Halfedge_const_handle, in case the vertical ray hits an arrangement edge;
• Arrangement_2::Vertex_const_handle, in case the vertical ray hits an arrangement vertex.
• Arrangement_2::Face_const_handle for the unbounded arrangement face, in case q lies above the upper envelope of the arrangement.

Precondition

rs is attached to a valid arrangement instance.