246 lines
9.2 KiB
C
246 lines
9.2 KiB
C
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// Copyright (c) 2005,2006,2007,2009,2010,2011 Tel-Aviv University (Israel).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org).
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// You can redistribute it and/or modify it under the terms of the GNU
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// General Public License as published by the Free Software Foundation,
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// either version 3 of the License, or (at your option) any later version.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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// SPDX-License-Identifier: GPL-3.0+
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//
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// Author(s) : Baruch Zukerman <baruchzu@post.tau.ac.il>
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// Efi Fogel <efifogel@gmail.com>
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// (based on old version by Tali Zvi)
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#ifndef CGAL_SURFACE_SWEEP_2_H
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#define CGAL_SURFACE_SWEEP_2_H
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#include <CGAL/license/Surface_sweep_2.h>
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/*! \file
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*
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* Definition of the Surface_sweep_2 class.
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*/
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#include <list>
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#include <vector>
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#include <CGAL/Object.h>
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#include <CGAL/No_intersection_surface_sweep_2.h>
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#include <CGAL/Surface_sweep_2/Curve_pair.h>
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#include <boost/unordered_set.hpp>
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#include <CGAL/algorithm.h>
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namespace CGAL {
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namespace Surface_sweep_2 {
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/*! \class
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*
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* Surface_sweep_2 is a class that implements the sweep line algorithm based
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* on the algorithm of Bentley and Ottmann.
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* It extends the algorithm to support not only segments but general x-monotone
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* curves as well and isolated points.
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* The X_monotone_curve_2 type and Point_2 are defined by the traits class that
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* is one of the template arguments.
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*
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* The algorithm is also extended to support the following degenerate cases:
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* - vertical segments
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* - multiple (more then two) curves intersecting at one point
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* - curves beginning and ending on other curves.
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* - overlapping curves
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*
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* General flow:
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* After the initialization stage, the events are handled from left to right.
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*
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* For each event
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*
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* First pass - handles special cases in which curves start or end
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* at the interior of another curve
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* Handle left curves - iterate over the curves that intersect
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* at the event point and defined lexicographically to the left
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* of the event.
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* Handle right curves - iterate over the curves that intersect
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* the event point and defined lexicographically to the right
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* of the event point. This is where new intersection points
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* are calculated.
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* End
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*
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* Convensions through out the code:
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* In order to make the code as readable as possible, some convensions were
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* made in regards to variable naming:
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*
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* xp - is the intersection point between two curves
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* slIter - an iterator to the status line, always points to a curve.
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*
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*/
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template <typename Visitor_>
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class Surface_sweep_2 : public No_intersection_surface_sweep_2<Visitor_> {
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public:
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typedef Visitor_ Visitor;
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private:
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typedef No_intersection_surface_sweep_2<Visitor> Base;
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public:
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typedef typename Base::Geometry_traits_2 Geometry_traits_2;
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typedef typename Base::Event Event;
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typedef typename Base::Subcurve Subcurve;
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typedef typename Base::Allocator Allocator;
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typedef typename Base::Traits_adaptor_2 Traits_adaptor_2;
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typedef typename Traits_adaptor_2::Point_2 Point_2;
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typedef typename Traits_adaptor_2::X_monotone_curve_2 X_monotone_curve_2;
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typedef typename Base::Event_queue_iterator Event_queue_iterator;
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typedef typename Event::Subcurve_iterator Event_subcurve_iterator;
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typedef typename Event::Attribute Attribute;
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typedef std::list<Subcurve*> Subcurve_container;
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typedef typename Subcurve_container::iterator Subcurve_iterator;
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typedef typename Base::Status_line_iterator Status_line_iterator;
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typedef CGAL::Surface_sweep_2::Curve_pair<Subcurve> Curve_pair;
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typedef boost::hash<Curve_pair> Curve_pair_hasher;
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typedef CGAL::Surface_sweep_2::Equal_curve_pair<Subcurve>
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Equal_curve_pair;
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typedef boost::unordered_set<Curve_pair, Curve_pair_hasher, Equal_curve_pair>
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Curve_pair_set;
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typedef std::vector<Object> Object_vector;
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typedef random_access_input_iterator<Object_vector> vector_inserter;
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typedef typename Base::Subcurve_alloc Subcurve_alloc;
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protected:
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// Data members:
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Subcurve_container m_overlap_subCurves;
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// Contains all of the new sub-curves
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// creaed by an overlap.
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Curve_pair_set m_curves_pair_set; // A lookup table of pairs of Subcurves
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// that have been intersected.
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std::vector<Object> m_x_objects; // Auxiliary vector for storing the
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// intersection objects.
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X_monotone_curve_2 sub_cv1; // Auxiliary varibales
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X_monotone_curve_2 sub_cv2; // (for splitting curves).
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public:
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/*! Constructor.
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* \param visitor A pointer to a sweep-line visitor object.
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*/
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Surface_sweep_2(Visitor* visitor) : Base(visitor), m_curves_pair_set(0) {}
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/*!
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* Construct.
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* \param traits A pointer to a sweep-line traits object.
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* \param visitor A pointer to a sweep-line visitor object.
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*/
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Surface_sweep_2(const Geometry_traits_2* traits, Visitor* visitor) :
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Base(traits, visitor),
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m_curves_pair_set(0)
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{}
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/*! Destrcut. */
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virtual ~Surface_sweep_2() {}
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protected:
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typedef typename std::vector<Subcurve*> Subcurve_vector;
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/*! Initialize the data structures for the sweep-line algorithm. */
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virtual void _init_structures();
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/*! Complete the sweep process (complete the data structures). */
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virtual void _complete_sweep();
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/*! Handle the subcurves to the left of the current event point. */
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virtual void _handle_left_curves();
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/*! Handle the subcurves to the right of the current event point. */
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virtual void _handle_right_curves();
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/*! Add a subcurve to the right of an event point.
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* \param event The event point.
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* \param curve The subcurve to add.
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*/
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virtual bool _add_curve_to_right(Event* event, Subcurve* curve);
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/*! Add a curve as a right curve or left curve when the event is created
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* or updated.
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*/
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void _add_curve(Event* e, Subcurve* sc, Attribute type);
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/*! Fix overlapping subcurves before handling the current event. */
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void _fix_overlap_subcurves();
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/*! create an overlap subcurve from overlap_cv between c1 and c2.
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* \param overlap_cv the overlapping curve.
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* \param c1 first subcurve contributing to the overlap.
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* \param c2 second subcurve contributing to the overlap.
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* \param all_leaves_diff not empty in case c1 and c2 have common ancesters.
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* It contains the set of curves not contained in first_parent
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* that are in the other subcurve
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* \param first_parent only used when c1 and c2 have common ancesters.
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* It is either c1 or c2 (the one having the more leaves)
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*
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*/
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void _create_overlapping_curve(const X_monotone_curve_2& overlap_cv,
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Subcurve*& c1 , Subcurve*& c2,
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const Subcurve_vector& all_leaves_diff,
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Subcurve* first_parent,
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Event* event_on_overlap);
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/*! Compute intersections between the two given curves.
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* If the two curves intersect, create a new event (or use the event that
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* already exits in the intersection point) and insert the curves to the
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* event.
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* \param curve1 The first curve.
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* \param curve2 The second curve.
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*/
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void _intersect(Subcurve* c1, Subcurve* c2, Event* event_for_overlap = NULL);
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/*! When a curve is removed from the status line for good, its top and
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* bottom neighbors become neighbors. This method finds these cases and
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* looks for the intersection point, if one exists.
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* \param leftCurve A pointer to the curve that is about to be deleted.
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* \param remove_for_good Whether the aubcurve is removed for good.
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*/
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void _remove_curve_from_status_line(Subcurve* leftCurve,
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bool remove_for_good);
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/*! Create an intersection-point event between two curves.
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* \param xp The intersection point.
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* \param mult Its multiplicity.
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* \param curve1 The first curve.
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* \param curve2 The second curve.
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*/
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void _create_intersection_point(const Point_2& xp,
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unsigned int mult,
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Subcurve*& c1,
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Subcurve*& c2);
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/*! Fix a subcurve that represents an overlap.
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* \param sc The subcurve.
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*/
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void _fix_finished_overlap_subcurve(Subcurve* sc);
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};
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} // namespace Surface_sweep_2
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} // namespace CGAL
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// The member-function definitions can be found in:
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#include <CGAL/Surface_sweep_2/Surface_sweep_2_impl.h>
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#endif
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