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// Copyright (c) 2000 Utrecht University (The Netherlands),
// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
// and Tel-Aviv University (Israel). All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.6-branch/Intersections_2/include/CGAL/Segment_2_Triangle_2_intersection.h $
// $Id: Segment_2_Triangle_2_intersection.h 51456 2009-08-24 17:10:04Z spion $
//
//
// Author(s) : Geert-Jan Giezeman
#ifndef CGAL_SEGMENT_2_TRIANGLE_2_INTERSECTION_H
#define CGAL_SEGMENT_2_TRIANGLE_2_INTERSECTION_H
#include <CGAL/Segment_2.h>
#include <CGAL/Triangle_2.h>
#include <CGAL/Point_2.h>
#include <CGAL/Line_2.h>
#include <CGAL/kernel_assertions.h>
#include <CGAL/number_utils.h>
#include <CGAL/Straight_2.h>
#include <CGAL/Object.h>
CGAL_BEGIN_NAMESPACE
namespace internal {
template <class K>
class Segment_2_Triangle_2_pair {
public:
enum Intersection_results {NO_INTERSECTION, POINT, SEGMENT};
Segment_2_Triangle_2_pair(typename K::Segment_2 const *seg,
typename K::Triangle_2 const *trian)
: _seg(seg), _trian(trian), _known(false) {}
Intersection_results intersection_type() const;
typename K::Point_2 intersection_point() const;
typename K::Segment_2 intersection_segment() const;
protected:
typename K::Segment_2 const * _seg;
typename K::Triangle_2 const * _trian;
mutable bool _known;
mutable Intersection_results _result;
mutable typename K::Point_2 _intersection_point;
mutable typename K::Point_2 _other_point;
};
template <class K>
inline bool do_intersect(
const typename K::Segment_2 &p1,
const typename K::Triangle_2 &p2,
const K&)
{
typedef Segment_2_Triangle_2_pair<K> pair_t;
pair_t pair(&p1, &p2);
return pair.intersection_type() != pair_t::NO_INTERSECTION;
}
template <class K>
typename Segment_2_Triangle_2_pair<K>::Intersection_results
Segment_2_Triangle_2_pair<K>::intersection_type() const
{
if (_known)
return _result;
// The non const this pointer is used to cast away const.
_known = true;
Straight_2_<K> straight(*_seg);
typedef typename K::Line_2 Line_2;
Line_2 l(_trian->vertex(0), _trian->vertex(1));
if (l.oriented_side(_trian->vertex(2)) == ON_POSITIVE_SIDE) {
straight.cut_right_off(
Line_2(_trian->vertex(0), _trian->vertex(1)));
straight.cut_right_off(
Line_2(_trian->vertex(1), _trian->vertex(2)));
straight.cut_right_off(
Line_2(_trian->vertex(2), _trian->vertex(0)));
} else {
straight.cut_right_off(
Line_2(_trian->vertex(2), _trian->vertex(1)));
straight.cut_right_off(
Line_2(_trian->vertex(1), _trian->vertex(0)));
straight.cut_right_off(
Line_2(_trian->vertex(0), _trian->vertex(2)));
}
switch (straight.current_state()) {
case Straight_2_<K>::EMPTY:
_result = NO_INTERSECTION;
return _result;
case Straight_2_<K>::POINT: {
straight.current(_intersection_point);
_result = POINT;
return _result;
}
case Straight_2_<K>::SEGMENT: {
typename K::Segment_2 seg;
straight.current(seg);
_intersection_point = seg.source();
_other_point = seg.target();
_result = SEGMENT;
return _result;
}
default: // should not happen.
CGAL_kernel_assertion_msg(false, "Internal CGAL error.");
_result = NO_INTERSECTION;
return _result;
}
}
template <class K>
typename K::Point_2
Segment_2_Triangle_2_pair<K>::
intersection_point() const
{
if (!_known)
intersection_type();
CGAL_kernel_assertion(_result == POINT);
return _intersection_point;
}
template <class K>
typename K::Segment_2
Segment_2_Triangle_2_pair<K>::
intersection_segment() const
{
typedef typename K::Segment_2 Segment_2;
if (!_known)
intersection_type();
CGAL_kernel_assertion(_result == SEGMENT);
return Segment_2(_intersection_point, _other_point);
}
template <class K>
Object
intersection(const typename K::Segment_2 &seg,
const typename K::Triangle_2&tr,
const K&)
{
typedef Segment_2_Triangle_2_pair<K> is_t;
is_t ispair(&seg, &tr);
switch (ispair.intersection_type()) {
case is_t::NO_INTERSECTION:
default:
return Object();
case is_t::POINT:
return make_object(ispair.intersection_point());
case is_t::SEGMENT:
return make_object(ispair.intersection_segment());
}
}
template <class K>
Object
intersection(const typename K::Triangle_2&tr,
const typename K::Segment_2 &seg,
const K& k)
{
return internal::intersection(seg, tr, k);
}
template <class K>
inline bool do_intersect(
const typename K::Triangle_2 &p1,
const typename K::Segment_2 &p2,
const K&)
{
typedef Segment_2_Triangle_2_pair<K> pair_t;
pair_t pair(&p2, &p1);
return pair.intersection_type() != pair_t::NO_INTERSECTION;
}
} // namespace internal
template <class K>
inline Object
intersection(const Segment_2<K> &seg, const Triangle_2<K> &tr)
{
typedef typename K::Intersect_2 Intersect;
return Intersect()(seg, tr);
}
template <class K>
inline Object
intersection(const Triangle_2<K> &tr, const Segment_2<K> &seg)
{
typedef typename K::Intersect_2 Intersect;
return Intersect()(seg, tr);
}
template <class K>
inline bool
do_intersect(const Segment_2<K> &seg, const Triangle_2<K> &tr)
{
typedef typename K::Do_intersect_2 Do_intersect;
return Do_intersect()(seg, tr);
}
template <class K>
inline bool
do_intersect(const Triangle_2<K> &tr, const Segment_2<K> &seg)
{
typedef typename K::Do_intersect_2 Do_intersect;
return Do_intersect()(seg, tr);
}
CGAL_END_NAMESPACE
#endif
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