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// Copyright (c) 2009 GeometryFactory (France), INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/Intersections_3/include/CGAL/Intersections_3/internal/Segment_3_Segment_3_intersection.h $
// $Id: include/CGAL/Intersections_3/internal/Segment_3_Segment_3_intersection.h 08b27d3db14 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s) : Sébastien Loriot
//
#ifndef CGAL_INTERNAL_INTERSECTIONS_3_SEGMENT_3_SEGMENT_3_INTERSECTION_H
#define CGAL_INTERNAL_INTERSECTIONS_3_SEGMENT_3_SEGMENT_3_INTERSECTION_H
#include <CGAL/Intersection_traits_3.h>
#include <CGAL/Intersections_3/internal/Line_3_Line_3_intersection.h>
namespace CGAL {
namespace Intersections {
namespace internal {
template <class K>
typename Intersection_traits<K, typename K::Segment_3, typename K::Segment_3>::result_type
intersection_collinear_segments(const typename K::Segment_3& s1,
const typename K::Segment_3& s2,
const K& k)
{
CGAL_precondition(!s1.is_degenerate() && !s2.is_degenerate());
const typename K::Point_3& p=s1[0], q=s1[1], r=s2[0], s=s2[1];
typename K::Collinear_are_ordered_along_line_3 cln_order=k.collinear_are_ordered_along_line_3_object();
if(cln_order(p,r,q))
{
if(cln_order(p,s,q))
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(s2);
if(cln_order(r,p,s))
{
if(r != p)
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>( typename K::Segment_3(r,p) );
if(cln_order(r,q,s))
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(s1);
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(p);
}
return (r != q) ? intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>( typename K::Segment_3(r,q) )
: intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(q);
}
if(cln_order(p,s,q))
{
if(cln_order(r,p,s))
{
if(s != p)
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>( typename K::Segment_3(s,p) );
if(cln_order(r,q,s))
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(s1);
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(p);
}
return (s != q) ? intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>( typename K::Segment_3(s,q) )
: intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(q);
}
if(cln_order(r,p,s))
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(s1);
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>();
}
template<class K>
struct L_p_visitor
{
typedef typename Intersection_traits<K, typename K::Segment_3, typename K::Segment_3>::result_type result_type;
L_p_visitor(const typename K::Segment_3& s1,
const typename K::Segment_3& s2)
: s1(s1), s2(s2)
{ }
const typename K::Segment_3& s1;
const typename K::Segment_3& s2;
result_type operator()(const typename K::Point_3& p) const
{
typename K::Collinear_are_ordered_along_line_3 cln_order = K().collinear_are_ordered_along_line_3_object();
if(cln_order(s1[0],p,s1[1]) && cln_order(s2[0],p,s2[1]))
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>(p);
else
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>();
}
result_type operator()(const typename K::Line_3&) const
{
return intersection_collinear_segments(s1,s2,K());
}
};
template <class K>
typename Intersection_traits<K, typename K::Segment_3, typename K::Segment_3>::result_type
intersection(const typename K::Segment_3& s1,
const typename K::Segment_3& s2,
const K& k)
{
CGAL_precondition(!s1.is_degenerate() && !s2.is_degenerate());
typename Intersection_traits<K, typename K::Line_3, typename K::Line_3>::result_type
v = internal::intersection(s1.supporting_line(), s2.supporting_line(), k);
if(v)
return std::visit(L_p_visitor<K>(s1, s2) , *v);
return intersection_return<typename K::Intersect_3, typename K::Segment_3, typename K::Segment_3>();
}
} // namespace internal
} // namespace Intersections
} // namespace CGAL
#endif // CGAL_INTERNAL_INTERSECTIONS_3_SEGMENT_3_SEGMENT_3_INTERSECTION_H
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