dust3d/thirdparty/cgal/CGAL-5.1/include/CGAL/Arrangement_zone_2.h

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// Copyright (c) 2006,2007,2009,2010,2011 Tel-Aviv University (Israel).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v5.1/Arrangement_on_surface_2/include/CGAL/Arrangement_zone_2.h $
// $Id: Arrangement_zone_2.h 58276ed 2020-03-31T18:34:28+03:00 Efi Fogel
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s): Ron Wein <wein@post.tau.ac.il>
// Efi Fogel <efif@post.tau.ac.il>
// (based on old version by Eyal Flato)
#ifndef CGAL_ARRANGEMENT_ZONE_2_H
#define CGAL_ARRANGEMENT_ZONE_2_H
#include <CGAL/license/Arrangement_on_surface_2.h>
#include <CGAL/disable_warnings.h>
/*! \file
* Defintion of the Arrangement_zone_2 class.
*/
#include <boost/mpl/assert.hpp>
#include <CGAL/Arr_tags.h>
#include <CGAL/Arr_accessor.h>
#include <CGAL/Arrangement_2/Arr_traits_adaptor_2.h>
#include <list>
#include <map>
#include <set>
namespace CGAL {
/*! \class
* A class for computing the zone of a given $x$-monotone curve in a given
* arrangement.
* The arrangement parameter corresponds to the underlying arrangement, and
* the zone-visitor parameter corresponds to a visitor class which is capable
* of receiving notifications on the arrangment features the query curve
* traverses. The visitor has to support the following functions:
* - init(), for initializing the visitor with a given arrangement.
* - found_subcurve(), called when a non-intersecting x-monotone curve is
* computed and located in the arrangement.
* - found_overlap(), called when an x-monotone curve overlaps an existing
* halfedge in the arrangement.
* Both the second and the third functions return pair<Halfedge_handle, bool>,
* where the halfedge handle corresponds to the halfedge created or modified
* by the visitor (if valid), and the Boolean value indicates whether we
* should halt the zone-computation process.
*/
template <typename Arrangement_, typename ZoneVisitor_>
class Arrangement_zone_2 {
public:
typedef Arrangement_ Arrangement_2;
typedef typename Arrangement_2::Geometry_traits_2 Geometry_traits_2;
typedef typename Arrangement_2::Topology_traits Topology_traits;
protected:
typedef Arr_traits_adaptor_2<Geometry_traits_2> Traits_adaptor_2;
typedef typename Traits_adaptor_2::Left_side_category Left_side_category;
typedef typename Traits_adaptor_2::Bottom_side_category Bottom_side_category;
typedef typename Traits_adaptor_2::Top_side_category Top_side_category;
typedef typename Traits_adaptor_2::Right_side_category Right_side_category;
BOOST_MPL_ASSERT
((typename Arr_sane_identified_tagging<Left_side_category,
Bottom_side_category,
Top_side_category,
Right_side_category>::result));
public:
typedef ZoneVisitor_ Visitor;
typedef typename Arrangement_2::Vertex_handle Vertex_handle;
typedef typename Arrangement_2::Halfedge_handle Halfedge_handle;
typedef typename Arrangement_2::Face_handle Face_handle;
typedef std::pair<Halfedge_handle, bool> Visitor_result;
typedef typename Geometry_traits_2::Point_2 Point_2;
typedef typename Geometry_traits_2::X_monotone_curve_2 X_monotone_curve_2;
typedef typename Geometry_traits_2::Multiplicity Multiplicity;
protected:
typedef typename Arr_are_all_sides_oblivious_tag<Left_side_category,
Bottom_side_category,
Top_side_category,
Right_side_category>::result
Are_all_sides_oblivious_category;
typedef typename Arrangement_2::Vertex_const_handle Vertex_const_handle;
typedef typename Arrangement_2::Halfedge_const_handle Halfedge_const_handle;
typedef typename Arrangement_2::Face_const_handle Face_const_handle;
typedef typename Arrangement_2::Ccb_halfedge_circulator
Ccb_halfedge_circulator;
// Types used for caching intersection points:
typedef std::pair<Point_2, Multiplicity> Intersection_point;
typedef boost::variant<Intersection_point, X_monotone_curve_2>
Intersection_result;
typedef boost::optional<Intersection_result> Optional_intersection;
typedef std::list<Intersection_result> Intersect_list;
typedef std::map<const X_monotone_curve_2*, Intersect_list>
Intersect_map;
typedef typename Intersect_map::iterator Intersect_map_iterator;
typedef std::set<const X_monotone_curve_2*> Curves_set;
typedef typename Curves_set::iterator Curves_set_iterator;
// Data members:
Arrangement_2& m_arr; // The associated arrangement.
const Traits_adaptor_2* m_geom_traits; // Its associated geometry traits.
Arr_accessor<Arrangement_2> m_arr_access; // An accessor for the arrangement.
Visitor* m_visitor; // The zone visitor.
Intersect_map m_inter_map; // Stores all computed intersections.
const Vertex_handle m_invalid_v; // An invalid vertex handle.
const Halfedge_handle m_invalid_he; // An invalid halfedge handle.
X_monotone_curve_2 m_cv; // The current portion of the
// inserted curve.
CGAL::Object m_obj; // The location of the left endpoint.
bool m_has_left_pt; // Is the left end of the curve bounded.
bool m_left_on_boundary; // Is the left point on the boundary.
Point_2 m_left_pt; // Its current left endpoint.
bool m_has_right_pt; // Is the right end of the curve bounded.
bool m_right_on_boundary; // Is the right point on the boundary.
Point_2 m_right_pt; // Its right endpoint (if bounded).
Vertex_handle m_left_v; // The arrangement vertex associated
// with the current left_pt (if any).
Halfedge_handle m_left_he; // If left_v is valid, left_he is the
// predecessor for cv around this
// vertex. Otherwise, if it is valid,
// it is the halfedge that contains
// the left endpoint it its interior.
Vertex_handle m_right_v; // The arrangement vertex associated
// with the current m_right_pt (if any).
Halfedge_handle m_right_he; // If m_right_v is valid, left_he is the
// predecessor for cv around this
// vertex. Otherwise, if it is valid,
// it is the halfedge that contains
// the right endpoint it its interior.
Point_2 m_intersect_p; // The next intersection point.
unsigned int m_ip_multiplicity; // Its multiplicity
// (0 in case of an overlap).
bool m_found_intersect; // An intersection has been found.
// (or an overlap).
X_monotone_curve_2 m_overlap_cv; // The currently discovered overlap.
bool m_found_overlap; // An overlap has been found.
bool m_found_iso_vert; // Check whether an isolated vertex
// induces the next intersection.
Vertex_handle m_intersect_v; // The vertex that intersects cv.
Halfedge_handle m_intersect_he; // The halfedge that intersects cv
// (or overlaps it).
X_monotone_curve_2 m_sub_cv1; // Auxiliary variable (for curve split).
X_monotone_curve_2 m_sub_cv2; // Auxiliary variable (for curve split).
public:
/*! Constructor.
* \param _arr The arrangement for which we compute the zone.
* \param _visitor A pointer to a zone-visitor object.
*/
Arrangement_zone_2(Arrangement_2& arr, Visitor* visitor) :
m_arr(arr),
m_arr_access(arr),
m_visitor(visitor),
m_invalid_v(),
m_invalid_he()
{
m_geom_traits = static_cast<const Traits_adaptor_2*>(arr.geometry_traits());
CGAL_assertion(visitor != nullptr);
// Initialize the visitor.
visitor->init(&arr);
}
/*! Initialize the zone-computation process with a given curve.
* \param _cv The query curve.
* \param pl A point-location object associated with the arrangement.
*/
template <typename PointLocation>
void init(const X_monotone_curve_2& cv, const PointLocation& pl)
{
// Set the curve and check whether its left end has boundary conditions.
m_cv = cv;
const Arr_parameter_space bx1 =
m_geom_traits->parameter_space_in_x_2_object()(m_cv, ARR_MIN_END);
const Arr_parameter_space by1 =
m_geom_traits->parameter_space_in_y_2_object()(m_cv, ARR_MIN_END);
if (bx1 == ARR_INTERIOR && by1 == ARR_INTERIOR) {
// The curve has a finite left endpoint with no boundary conditions:
// locate it in the arrangement.
m_has_left_pt = true;
m_left_on_boundary = (bx1 != ARR_INTERIOR || by1 != ARR_INTERIOR);
m_left_pt = m_geom_traits->construct_min_vertex_2_object()(m_cv);
m_obj = pl.locate(m_left_pt);
}
else {
// The left end of the curve has boundary conditions: use the topology
// traits use the arrangement accessor to locate it.
// Note that if the curve-end is unbounded, m_left_pt does not exist.
// Note that if the curve-end is unbounded, m_left_pt does not exist.
m_has_left_pt = m_geom_traits->is_closed_2_object()(m_cv, ARR_MIN_END);
m_left_on_boundary = true;
if (m_has_left_pt)
m_left_pt = m_geom_traits->construct_min_vertex_2_object()(m_cv);
m_obj = m_arr_access.locate_curve_end(m_cv, ARR_MIN_END, bx1, by1);
}
// Check the boundary conditions of th right curve end.
if (m_geom_traits->is_closed_2_object()(m_cv, ARR_MAX_END)) {
const Arr_parameter_space bx2 =
m_geom_traits->parameter_space_in_x_2_object()(m_cv, ARR_MAX_END);
const Arr_parameter_space by2 =
m_geom_traits->parameter_space_in_y_2_object()(m_cv, ARR_MAX_END);
// The right endpoint is valid.
m_has_right_pt = true;
m_right_pt = m_geom_traits->construct_max_vertex_2_object()(m_cv);
m_right_on_boundary = (bx2 != ARR_INTERIOR) || (by2 != ARR_INTERIOR);
}
else {
// The right end of the curve lies at infinity.
m_has_right_pt = false;
m_right_on_boundary = true;
}
}
/*! Initialize the zone-computation process with a given curve and an object
* that wraps the location of the curve's left end.
* \param cv The query curve.
* \param obj An object that represents the location of the left end of the
* curve.
*/
void init_with_hint(const X_monotone_curve_2& cv, const Object& obj);
/*! Compute the zone of the given curve and issue the apporpriate
* notifications for the visitor.
*/
void compute_zone();
private:
/*! Check whether two curves with a common endpoint overlap.
* \pre p == min_point(cv1)
* \pre p == min_point(cv2)
* \todo move this function to a more accessible place so that it can be reused
*/
bool do_overlap(const X_monotone_curve_2& cv1, const X_monotone_curve_2& cv2,
const Point_2& p) const
{ return do_overlap_impl(cv1, cv2, p, Are_all_sides_oblivious_category()); }
/*! Check whether two curves with a common min endpoint overlap.
*/
bool do_overlap_impl(const X_monotone_curve_2& cv1,
const X_monotone_curve_2& cv2,
const Point_2& p, Arr_all_sides_oblivious_tag) const
{
return m_geom_traits->compare_y_at_x_right_2_object()(cv1, cv2, p) == EQUAL;
}
/*! Check whether two curves with a common min endpoint overlap.
*/
bool do_overlap_impl(const X_monotone_curve_2& cv1,
const X_monotone_curve_2& cv2,
const Point_2& p, Arr_not_all_sides_oblivious_tag) const;
/* Check whether the given query curve is encountered when rotating the
* first curve in a clockwise direction around a given point until reaching
* the second curve.
* \pre p == min_point(xcv)
* \pre p == min_point(xcv1)
* \pre p == min_point(cxv2)
* \pre xcv_to_right == TRUE
* \todo move this function to a more accessible place so that it can be reused
*/
bool is_between_cw(const X_monotone_curve_2& xcv, bool xcv_to_right,
const X_monotone_curve_2& xcv1, bool xcv1_to_right,
const X_monotone_curve_2& xcv2, bool xcv2_to_right,
const Point_2& p,
bool& xcv_equal_xcv1, bool& xcv_equal_xcv2) const
{
return is_between_cw_impl(xcv, xcv_to_right,
xcv1, xcv1_to_right,
xcv2, xcv2_to_right,
p, xcv_equal_xcv1, xcv_equal_xcv2,
Are_all_sides_oblivious_category());
}
/* Check whether the given query curve is encountered when rotating the
* first curve in a clockwise direction around a given point until reaching
* the second curve.
*/
bool is_between_cw_impl(const X_monotone_curve_2& xcv, bool xcv_to_right,
const X_monotone_curve_2& xcv1, bool xcv1_to_right,
const X_monotone_curve_2& xcv2, bool xcv2_to_right,
const Point_2& p,
bool& xcv_equal_xcv1, bool& xcv_equal_xcv2,
Arr_all_sides_oblivious_tag) const
{
return m_geom_traits->is_between_cw_2_object()(xcv, xcv_to_right,
xcv1, xcv1_to_right,
xcv2, xcv2_to_right,
p,
xcv_equal_xcv1,
xcv_equal_xcv2);
}
/* Check whether the given query curve is encountered when rotating the
* first curve in a clockwise direction around a given point until reaching
* the second curve.
*/
bool is_between_cw_impl(const X_monotone_curve_2& xcv, bool xcv_to_right,
const X_monotone_curve_2& xcv1, bool xcv1_to_right,
const X_monotone_curve_2& xcv2, bool xcv2_to_right,
const Point_2& p,
bool& xcv_equal_xcv1, bool& xcv_equal_xcv2,
Arr_not_all_sides_oblivious_tag) const;
/*! Find a face containing the query curve m_cv around the given vertex.
* In case an overlap occurs, sets m_intersect_he to be the overlapping edge.
* \param v The query vertex.
* \param he Output: The predecessor of m_cv around the vertex.
* \return (true) if m_cv overlaps with the curve associated with he;
* (false) if there is no overlap.
*/
bool _find_prev_around_vertex(Vertex_handle v, Halfedge_handle& he);
/*! Direct the halfedge for the location of the given subcurve around a split
* point that occurs in the interior of a given edge, when the subcurve lies
* to the right of the split point.
* In case of overlaps, it sets also m_found_overlap and m_intersect_he.
* \param cv_ins The curve to be inserted, whose left endpoint coincides
* with the edge to be split.
* \param cv_left_pt The left endpoint of cv_ins.
* \param query_he The edge that intersects cv_ins.
* \pre The left endpoint of cv_ins lies in the interior of the curve
* associated with query_he.
* \return The halfedge whose incident face contains cv_ins
* (either query_he or its twin).
*/
Halfedge_handle
_direct_intersecting_edge_to_right(const X_monotone_curve_2& cv_ins,
const Point_2& cv_left_pt,
Halfedge_handle query_he);
/*! Direct the halfedge for the location of the given subcurve around a split
* point that occurs in the interior of a given edge, when the subcurve lies
* to the left of the split point.
* \param cv_ins The curve to be inserted, whose right endpoint coincides
* with the edge to be split.
* \param query_he The edge that intersects cv_ins.
* \pre The right endpoint of cv_ins lies in the interior of the curve
* associated with query_he.
* \return The halfedge whose incident face contains cv_ins
* (either query_he or its twin).
*/
Halfedge_handle
_direct_intersecting_edge_to_left(const X_monotone_curve_2& cv_ins,
Halfedge_handle query_he);
/*! Get the next intersection of m_cv with the given halfedge.
* \param he A handle to the halfedge.
* \param skip_first_point Should we skip the first intersection point.
* \param intersect_on_right_boundary Output: If an intersetion point is
* computed, marks whether this
* point coincides with the right
* curve-end, which lies on the
* surface boundary.
* \return An object representing the next intersection: Intersection_point
* in case of a simple intersection point, X_monotone_curve_2 in
* case of an overlap, and an empty object if there is no
* intersection.
*/
Optional_intersection
_compute_next_intersection(Halfedge_handle he,
bool skip_first_point,
bool& intersect_on_right_boundary);
/*! Remove the next intersection of m_cv with the given halfedge from the map.
* \param he A handle to the halfedge.
* \pre The list of intersections with the curve of he has already been
* computed, and it is not empty.
*/
void _remove_next_intersection (Halfedge_handle he);
/*! Check whether the given point lies completely to the left of the given
* egde.
* \param p The point.
* \param he The halfedge.
* \pre he is not a fictitious edge.
* \return Whether p lies entirely to the left of the edge.
*/
bool _is_to_left(const Point_2& p, Halfedge_handle he) const
{
return (_is_to_left_impl(p, he, Are_all_sides_oblivious_category()));
}
bool _is_to_left_impl(const Point_2& p, Halfedge_handle he,
Arr_all_sides_oblivious_tag) const
{
return (((he->direction() == ARR_LEFT_TO_RIGHT) &&
m_geom_traits->compare_xy_2_object()
(p, he->source()->point()) == SMALLER) ||
(he->direction() == ARR_RIGHT_TO_LEFT &&
m_geom_traits->compare_xy_2_object()
(p, he->target()->point()) == SMALLER));
}
bool _is_to_left_impl(const Point_2& p, Halfedge_handle he,
Arr_not_all_sides_oblivious_tag) const;
/*! Check whether the given point lies completely to the right of the given
* egde.
* \param p The point.
* \param he The halfedge.
* \pre he is not a fictitious edge.
* \return Whether p lies entirely to the right of the edge.
*/
bool _is_to_right(const Point_2& p, Halfedge_handle he) const
{
return (_is_to_right_impl(p, he, Are_all_sides_oblivious_category()));
}
bool _is_to_right_impl(const Point_2& p, Halfedge_handle he,
Arr_all_sides_oblivious_tag) const
{
return (((he->direction() == ARR_LEFT_TO_RIGHT) &&
m_geom_traits->compare_xy_2_object()(p, he->target()->point()) ==
LARGER) ||
((he->direction() == ARR_RIGHT_TO_LEFT) &&
m_geom_traits->compare_xy_2_object()(p, he->source()->point()) ==
LARGER));
}
bool _is_to_right_impl(const Point_2& p, Halfedge_handle he,
Arr_not_all_sides_oblivious_tag) const;
/*! Compute the (lexicographically) leftmost intersection of the query
* curve with a given halfedge on the boundary of a face in the arrangement.
*/
void
_leftmost_intersection(Ccb_halfedge_circulator he_curr, bool on_boundary,
bool& leftmost_on_right_boundary);
/*! Compute the (lexicographically) leftmost intersection of the query
* curve with the boundary of a given face in the arrangement.
* The function computes sets m_intersect_p, m_intersect_he (or alternatively
* m_overlap_cv and m_intersect_he) and set the flags m_found_intersect and
* m_found_overlap accordingly.
* \param face A handle to the face.
* \param on_boundary Specifies whether the left endpoint of the curve lies
* on the face boundary.
*/
void _leftmost_intersection_with_face_boundary(Face_handle face,
bool on_boundary);
/*! Compute the zone of an x-monotone curve in a given arrangement face.
* The left endpoint of the curve either lies in the face interior or on
* the boundary of the face.
* This function updates m_cv and its left endpoint and also sets m_left_v
* and m_left_he for the remaining portion of the curve.
* In case of overlaps, it sets also m_overlap_cv and m_intersect_he.
* \param face The given face.
* \param on_boundary Specifies whether the left endpoint of the curve lies
* on the face boundary.
* \pre If on_boundary is (true) then m_left_he must be valid; if it is
* (false), then both m_left_v anf m_left_he must be invalid.
* \return (true) if we are done with the zone-computation process;
* (false) if we still have a remaining portion of m_cv to continue
* with.
*/
bool _zone_in_face(Face_handle face, bool on_boundary);
/*! Compute the zone of an overlapping subcurve m_overlap_cv of m_cv and the
* curve currently associated with m_intersect_he.
* This function updates m_cv and its left endpoint and also sets m_left_v
* and m_left_he for the remaining portion of the curve.
* \return (true) if we are done with the zone-computation process;
* (false) if we still have a remaining portion of m_cv to continue
* with.
*/
bool _zone_in_overlap();
};
} //namespace CGAL
// The function definitions can be found under:
#include <CGAL/Arrangement_2/Arrangement_zone_2_impl.h>
#include <CGAL/enable_warnings.h>
#endif