389 lines
13 KiB
C
389 lines
13 KiB
C
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// Copyright (c) 1997-2002 Max-Planck-Institute Saarbruecken (Germany).
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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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//
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// $URL: https://github.com/CGAL/cgal/blob/v5.1/Nef_S2/include/CGAL/Nef_S2/Sphere_segment.h $
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// $Id: Sphere_segment.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
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// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
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//
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//
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// Author(s) : Michael Seel <seel@mpi-sb.mpg.de>
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#ifndef CGAL_SPHERE_SEGMENT_H
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#define CGAL_SPHERE_SEGMENT_H
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#include <CGAL/license/Nef_S2.h>
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#include <CGAL/basic.h>
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#include <CGAL/Handle_for.h>
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#include <vector>
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namespace CGAL {
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template <class R_> class Sphere_segment_rep
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{
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typedef typename R_::Point_3 Point_3;
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typedef typename R_::Plane_3 Plane_3;
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typedef Sphere_point<R_> Point;
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typedef Sphere_circle<R_> Circle;
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typedef Sphere_segment_rep<R_> Rep;
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friend class Sphere_segment<R_>;
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public:
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Sphere_segment_rep() { ps_ = pt_ = Point(); c_ = Circle(); }
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Sphere_segment_rep(const Point& p1, const Point& p2,
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bool shorter_arc=true) :
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ps_(p1), pt_(p2), c_(Plane_3(p1,p2,Point_3(0,0,0)))
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{ // warning stays as reminder that one gets an arbitrary plane equation
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// in this degenerate case
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CGAL_warning(p1 != p2.antipode());
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CGAL_assertion(p1 != p2.antipode());
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if ( p1 == p2 ) {
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Plane_3 h(Point_3(0,0,0),(p1-CGAL::ORIGIN));
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c_ = Sphere_circle<R_>(Plane_3(Point_3(0,0,0),h.base1()));
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}
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if (!shorter_arc) c_ = c_.opposite();
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CGAL_exactness_assertion(c_.has_on(p1) && c_.has_on(p2));
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}
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Sphere_segment_rep(const Point& p1, const Point& p2, const Circle& c) :
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ps_(p1), pt_(p2), c_(c)
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{ CGAL_assertion(c.has_on(p1)&&c.has_on(p2)); }
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Sphere_segment_rep(const Circle& c1,
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const Circle& c2) : c_(c1)
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{ CGAL_assertion(!equal_as_sets(c1,c2));
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ps_ = intersection(c1,c2);
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pt_ = ps_.antipode();
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if ( R_::orientation(Point_3(0,0,0),ps_,pt_,
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CGAL::ORIGIN + c_.orthogonal_vector()) !=
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CGAL::POSITIVE ) std::swap(ps_,pt_);
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}
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Sphere_segment_rep(const Rep& r) :
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ps_(r.ps_), pt_(r.pt_), c_(r.c_) {}
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Rep& operator=(const Rep& r)
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{ ps_=r.ps_; pt_=r.pt_; c_=r.c_; return *this; }
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protected:
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Sphere_point<R_> ps_,pt_;
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Sphere_circle<R_> c_;
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};
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/*{\Moptions print_title=yes }*/
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/*{\Manpage{Sphere_segment}{R}{Segments on the unit sphere}{s}}*/
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template <class R_>
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class Sphere_segment :
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public Handle_for< Sphere_segment_rep<R_> > {
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/*{\Mdefinition An object |\Mvar| of type |\Mname| is a segment in the
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surface of a unit sphere that is part of a great circle trough the
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origin. Sphere segments are represented by two sphere points $p$ and
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$q$ plus an oriented plane $h$ that contains $p$ and $q$. The plane
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determines the sphere segment. Let $c$ be the circle in the
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intersection of $h$ and $S_2$. Then $s$ is that part of $c$ that is
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swept, when we rotate $p$ into $q$ in counterclockwise rotation around
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the normal vector of $h$ as seen from the positive halfspace.}*/
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public:
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/*{\Mtypes 6}*/
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typedef R_ R;
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/*{\Mtypemember representation class.}*/
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typedef typename R_::RT RT;
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/*{\Mtypemember ring number type.}*/
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typedef Sphere_segment_rep<R_> Rep;
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typedef Handle_for<Rep> Base;
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typedef typename R_::Point_3 Point_3;
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typedef typename R_::Vector_3 Vector_3;
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typedef typename R_::Plane_3 Plane_3;
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typedef typename R_::Line_3 Line_3;
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typedef Sphere_segment<R_> Self;
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/*{\Mcreation 4}*/
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Sphere_segment() : Base() {}
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Sphere_segment(const Sphere_point<R>& p1, const Sphere_point<R>& p2,
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bool shorter_arc=true) : Base(Rep(p1,p2,shorter_arc)) {}
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/*{\Mcreate creates a spherical segment spanning the shorter arc
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from |p1| to |p2| if |shorter_arc == true|. Otherwise the longer
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arc is created. \precond |p1 != p2| and |p1 != p2.antipode()|.}*/
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Sphere_segment(const Sphere_point<R>& p1, const Sphere_point<R>& p2,
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const Sphere_circle<R>& c) : Base(Rep(p1,p2,c)) {}
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/*{\Mcreate creates a spherical segment spanning the arc
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from |p1| to |p2| as part of the oriented circle |c|
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(|p1 == p2| or |p1 == p2.antipode()| are possible.)
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\precond |p1| and |p2| are contained in |c|.}*/
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Sphere_segment(const Sphere_circle<R>& c1,
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const Sphere_circle<R>& c2) : Base(Rep(c1,c2)) {}
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/*{\Mcreate creates the spherical segment as part of |c1|
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that is part of the halfsphere left of the oriented circle |c2|.
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\precond |c1 != c2| as unoriented circles.}*/
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// Sphere_segment(const Self& s) : Base(s) {}
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/*{\Moperations 4 2}*/
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const Sphere_point<R>& source() const { return this->ptr()->ps_; }
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/*{\Mop the source point of |\Mvar|.}*/
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const Sphere_point<R>& target() const { return this->ptr()->pt_; }
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/*{\Mop the target point of |\Mvar|.}*/
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const Sphere_circle<R>& sphere_circle() const { return this->ptr()->c_; }
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/*{\Mop the great circle supporting |\Mvar|.}*/
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Sphere_segment<R> opposite() const
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/*{\Mop returns the sperical segment oriented from |target()|
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to |source()| with the same point set as |\Mvar|. }*/
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{ return Sphere_segment<R>(
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target(),source(),sphere_circle().opposite()); }
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Sphere_segment<R> complement() const
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/*{\Mop returns the sperical segment oriented from |target()|
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to |source()| with the point set completing |\Mvar| to a
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full circle. }*/
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{ return Sphere_segment<R>(target(),source(),sphere_circle()); }
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int intersection(const Sphere_circle<R>& c,
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std::vector<Sphere_segment<R> >& s) const;
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int intersection(const Sphere_circle<R>& c,
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Sphere_segment<R>& s1, Sphere_segment<R>& s2) const;
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/*{\Mop returns the number of non-trivial connected components
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of the intersection of |\Mvar| and the closed halfsphere left of
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|c|.}*/
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Sphere_point<R> intersection(const Sphere_segment<R>& so) const;
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/*{\Mop returns the point of intersection of |\Mvar| and
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|so|. \precond |\Mvar| and |so| do intersect.}*/
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void split_halfcircle(Sphere_segment<R>& s1,
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Sphere_segment<R>& s2) const
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/*{\Mop splits a halfcircle into two equally sized segments.
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\precond |\Mvar| is a halfcircle.}*/
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{ CGAL_assertion( is_halfcircle() );
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Plane_3 h(Point_3(0,0,0),(target()-CGAL::ORIGIN));
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Sphere_point<R> p =
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CGAL::intersection(sphere_circle(),Sphere_circle<R>(h));
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if ( !has_on(p) ) p = p.antipode();
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s1 = Sphere_segment<R>(this->ptr()->ps_,p,this->ptr()->c_);
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s2 = Sphere_segment<R>(p,this->ptr()->pt_,this->ptr()->c_);
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}
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bool is_short() const
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/*{\Mop a segment is short iff it is shorter than a halfcircle.}*/
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{
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return R().orientation_3_object()(Point_3(0,0,0),
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Point_3(source()),
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Point_3(target()),
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CGAL::ORIGIN +
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this->ptr()->c_.orthogonal_vector())
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== CGAL::POSITIVE; }
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bool is_long() const
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/*{\Mop a segment is long iff it is longer than a halfcircle.}*/
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{ return R().orientation_3_object()(Point_3(0,0,0),
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Point_3(source()),
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Point_3(target()),
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CGAL::ORIGIN + this->ptr()->c_.orthogonal_vector())
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== CGAL::NEGATIVE; }
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bool is_degenerate() const { return source() == target(); }
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/*{\Mop return true iff |\Mvar| is degenerate.}*/
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bool is_halfcircle() const { return source().antipode() == target(); }
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/*{\Mop return true iff |\Mvar| is a halfcircle.}*/
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bool has_on(const Sphere_point<R>& p) const;
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/*{\Mop return true iff |\Mvar| contains |p|.}*/
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bool has_on_after_intersection(const Sphere_point<R>& p) const;
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bool has_in_relative_interior(const Sphere_point<R>& p) const;
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/*{\Mop return true iff |\Mvar| contains |p| in
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its relative interior.}*/
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bool operator==(const Sphere_segment<R>& so) const
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{ return source() == so.source() && target() == so.target() &&
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(source() == target() ||
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sphere_circle() == so.sphere_circle()); }
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bool operator!=(const Sphere_segment<R>& so) const
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{ return !operator==(so); }
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};
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template <typename R>
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bool do_intersect_internally(const Sphere_segment<R>& s1,
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const Sphere_segment<R>& s2,
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Sphere_point<R>& p);
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/*{\Mfunc return true iff |s1| and |s2| intersect internally
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(non-degenerately). If |true| the parameter |p| returns the point of
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intersection.}*/
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template <typename R>
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std::ostream& operator<<(std::ostream& os,
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const CGAL::Sphere_segment<R>& s)
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{ os << s.source()<<" "<<s.target()<<" "<<
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s.sphere_circle().plane()<<" "; return os; }
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template <typename R>
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std::istream& operator>>(std::istream& is,
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CGAL::Sphere_segment<R>& s)
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{ CGAL::Sphere_point<R> p1,p2;
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CGAL::Sphere_circle<R> c;
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if ( !(is >> p1 >> p2 >> c) ) return is;
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s = CGAL::Sphere_segment<R>(p1,p2,c);
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return is; }
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template <typename R>
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std::pair< Sphere_segment<R>,Sphere_segment<R> >
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Sphere_circle<R>::split_at(const Sphere_point<R>& p) const
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{ CGAL_assertion(has_on(p));
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Sphere_point<R> q(p.antipode());
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return Sphere_segment_pair(
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Sphere_segment<R>(p,q,*this),
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Sphere_segment<R>(p,q,this->opposite()));
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}
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template <typename R>
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std::pair< Sphere_segment<R>,Sphere_segment<R> >
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Sphere_circle<R>::split_at_xy_plane() const
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{ Self xycircle(0,0,1), yzcircle(1,0,0);
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if ( !equal_as_sets(xycircle,*this) )
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return split_at(intersection(*this,xycircle));
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else
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return split_at(intersection(*this,yzcircle));
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}
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/* Contains maps to two orientation checks with the wedge
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spanned by the source and the target with planes orthogonal
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to the supporting plane of $p$ and $q$. The logic depends on
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the segments length: long or short. */
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template <typename R>
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bool Sphere_segment<R>::
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has_on(const CGAL::Sphere_point<R>& p) const
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{ if ( !sphere_circle().has_on(p) ) return false;
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if ( !is_long() ) {
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return orientation(Point_3(0,0,0),
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CGAL::ORIGIN + sphere_circle().orthogonal_vector(),
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source(),p) !=
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CGAL::NEGATIVE &&
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orientation(Point_3(0,0,0),target(),
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CGAL::ORIGIN +
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sphere_circle().orthogonal_vector(),p) !=
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CGAL::NEGATIVE;
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} else {
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return orientation(Point_3(0,0,0),
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CGAL::ORIGIN + sphere_circle().orthogonal_vector(),
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source(),p) !=
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CGAL::NEGATIVE ||
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orientation(Point_3(0,0,0),target(),
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CGAL::ORIGIN +
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sphere_circle().orthogonal_vector(),p) !=
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CGAL::NEGATIVE;
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}
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}
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template <typename R>
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bool Sphere_segment<R>::
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has_on_after_intersection(const CGAL::Sphere_point<R>& p) const {
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return orientation(Point_3(0,0,0),
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CGAL::ORIGIN + sphere_circle().orthogonal_vector(),
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source(),p) !=
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CGAL::NEGATIVE &&
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orientation(Point_3(0,0,0),target(),
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CGAL::ORIGIN +
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sphere_circle().orthogonal_vector(),p) !=
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CGAL::NEGATIVE;
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}
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template <typename R>
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bool Sphere_segment<R>::
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has_in_relative_interior(const CGAL::Sphere_point<R>& p) const
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{ if ( !sphere_circle().has_on(p) ) return false;
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if ( !is_long() ) {
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return orientation(Point_3(0,0,0),
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CGAL::ORIGIN + sphere_circle().orthogonal_vector(),
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source(),p) == CGAL::POSITIVE &&
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orientation(Point_3(0,0,0),target(),
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CGAL::ORIGIN +
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sphere_circle().orthogonal_vector(),p) ==
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CGAL::POSITIVE;
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} else {
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return orientation(Point_3(0,0,0),
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CGAL::ORIGIN + sphere_circle().orthogonal_vector(),
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source(),p) == CGAL::POSITIVE ||
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orientation(Point_3(0,0,0),target(),
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CGAL::ORIGIN +
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sphere_circle().orthogonal_vector(),p) ==
|
||
|
|
CGAL::POSITIVE;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
/* Intersection of two sphere segments. It does not work if the two
|
||
|
|
involved planes are equal as sets. */
|
||
|
|
|
||
|
|
template <typename R>
|
||
|
|
Sphere_point<R> Sphere_segment<R>::
|
||
|
|
intersection(const Sphere_segment<R>& s) const
|
||
|
|
{
|
||
|
|
CGAL_assertion(!equal_as_sets(sphere_circle(),s.sphere_circle()));
|
||
|
|
Sphere_point<R> res =
|
||
|
|
CGAL::intersection(sphere_circle(),s.sphere_circle());
|
||
|
|
if ( has_on(res) && s.has_on(res) ) return res;
|
||
|
|
return res.antipode();
|
||
|
|
}
|
||
|
|
|
||
|
|
template <typename R>
|
||
|
|
bool do_intersect_internally(const Sphere_segment<R>& s1,
|
||
|
|
const Sphere_segment<R>& s2,
|
||
|
|
Sphere_point<R>& p)
|
||
|
|
{
|
||
|
|
if ( equal_as_sets(s1.sphere_circle(),s2.sphere_circle()) )
|
||
|
|
return false;
|
||
|
|
p = CGAL::intersection(s1.sphere_circle(),s2.sphere_circle());
|
||
|
|
if ( s1.has_in_relative_interior(p) &&
|
||
|
|
s2.has_in_relative_interior(p) ) return true;
|
||
|
|
p = p.antipode();
|
||
|
|
if ( s1.has_in_relative_interior(p) &&
|
||
|
|
s2.has_in_relative_interior(p) ) return true;
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
template <typename R>
|
||
|
|
bool do_intersect_internally(const Sphere_circle<R>& c1,
|
||
|
|
const Sphere_segment<R>& s2,
|
||
|
|
Sphere_point<R>& p)
|
||
|
|
{
|
||
|
|
if ( equal_as_sets(c1,s2.sphere_circle()) )
|
||
|
|
return false;
|
||
|
|
p = CGAL::intersection(c1,s2.sphere_circle());
|
||
|
|
if ( s2.has_in_relative_interior(p) ) return true;
|
||
|
|
p = p.antipode();
|
||
|
|
if ( s2.has_in_relative_interior(p) ) return true;
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
} //namespace CGAL
|
||
|
|
#endif //CGAL_SPHERE_SEGMENT_H
|