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// Copyright (c) 2000
// Utrecht University (The Netherlands),
// ETH Zurich (Switzerland),
// INRIA Sophia-Antipolis (France),
// Max-Planck-Institute Saarbruecken (Germany),
// and Tel-Aviv University (Israel). All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/Intersections_2/include/CGAL/Intersections_2/Line_2_Segment_2.h $
// $Id: include/CGAL/Intersections_2/Line_2_Segment_2.h 08b27d3db14 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s) : Geert-Jan Giezeman
#ifndef CGAL_INTERSECTIONS_2_SEGMENT_2_LINE_2_H
#define CGAL_INTERSECTIONS_2_SEGMENT_2_LINE_2_H
#include <CGAL/Line_2.h>
#include <CGAL/Segment_2.h>
#include <CGAL/kernel_assertions.h>
#include <CGAL/number_utils.h>
#include <CGAL/Intersections_2/Line_2_Line_2.h>
#include <CGAL/Intersection_traits_2.h>
namespace CGAL {
namespace Intersections {
namespace internal {
template <class K>
class Segment_2_Line_2_pair {
public:
enum Intersection_results {NO_INTERSECTION, POINT, SEGMENT, UNKNOWN};
Segment_2_Line_2_pair(typename K::Segment_2 const *seg,
typename K::Line_2 const *line)
: _seg(seg), _line(line) {}
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::Line_2 const * _line;
mutable Intersection_results _result = UNKNOWN;
mutable typename K::Point_2 _intersection_point;
};
template <class K>
inline
typename K::Boolean
do_intersect(const typename K::Segment_2& s,
const typename K::Line_2& l,
const K& )
{
typedef Segment_2_Line_2_pair<K> pair_t;
pair_t pair(&s, &l);
return pair.intersection_type() != pair_t::NO_INTERSECTION;
}
template <class K>
inline
typename K::Boolean
do_intersect(const typename K::Line_2& l,
const typename K::Segment_2& s,
const K& k)
{
return internal::do_intersect(s, l, k);
}
template <class K>
typename CGAL::Intersection_traits
<K, typename K::Segment_2, typename K::Line_2>::result_type
intersection(const typename K::Segment_2 &seg,
const typename K::Line_2 &line,
const K&)
{
typedef Segment_2_Line_2_pair<K> is_t;
is_t ispair(&seg, &line);
switch (ispair.intersection_type()) {
case is_t::NO_INTERSECTION:
default:
return intersection_return<typename K::Intersect_2, typename K::Line_2, typename K::Segment_2>();
case is_t::POINT:
return intersection_return<typename K::Intersect_2, typename K::Line_2, typename K::Segment_2>(ispair.intersection_point());
case is_t::SEGMENT:
return intersection_return<typename K::Intersect_2, typename K::Line_2, typename K::Segment_2>(seg);
}
}
template <class K>
typename CGAL::Intersection_traits
<K, typename K::Line_2, typename K::Segment_2>::result_type
intersection(const typename K::Line_2 &line,
const typename K::Segment_2 &seg,
const K& k)
{
return internal::intersection(seg, line, k);
}
template <class K>
typename Segment_2_Line_2_pair<K>::Intersection_results
Segment_2_Line_2_pair<K>::intersection_type() const
{
if (_result!=UNKNOWN)
return _result;
// The non const this pointer is used to cast away const.
const typename K::Line_2 &l1 = _seg->supporting_line();
Line_2_Line_2_pair<K> linepair(&l1, _line);
switch ( linepair.intersection_type()) {
case Line_2_Line_2_pair<K>::NO_INTERSECTION:
_result = NO_INTERSECTION;
break;
case Line_2_Line_2_pair<K>::POINT:
_intersection_point = linepair.intersection_point();
_result = (_seg->collinear_has_on(_intersection_point) )
? POINT : NO_INTERSECTION;
break;
case Line_2_Line_2_pair<K>::LINE:
_result = SEGMENT;
break;
default:
CGAL_unreachable();
}
return _result;
}
template <class K>
typename K::Point_2
Segment_2_Line_2_pair<K>::intersection_point() const
{
if (_result==UNKNOWN)
intersection_type();
CGAL_kernel_assertion(_result == POINT);
return _intersection_point;
}
template <class K>
typename K::Segment_2
Segment_2_Line_2_pair<K>::intersection_segment() const
{
if (_result==UNKNOWN)
intersection_type();
CGAL_kernel_assertion(_result == SEGMENT);
return *_seg;
}
} // namespace internal
} // namespace Intersections
CGAL_INTERSECTION_FUNCTION(Segment_2, Line_2, 2)
CGAL_DO_INTERSECT_FUNCTION(Segment_2, Line_2, 2)
} // namespace CGAL
#endif // CGAL_INTERSECTIONS_2_SEGMENT_2_LINE_2_H
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