// 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); 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; either version 3 of the License, // or (at your option) any later version. // // 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. // // $URL$ // $Id$ // // // Author(s) : Geert-Jan Giezeman #ifndef CGAL_SEGMENT_2_LINE_2_INTERSECTION_H #define CGAL_SEGMENT_2_LINE_2_INTERSECTION_H #include #include #include #include #include #include #include namespace CGAL { namespace internal { template class Segment_2_Line_2_pair { public: enum Intersection_results {NO_INTERSECTION, POINT, SEGMENT}; Segment_2_Line_2_pair(typename K::Segment_2 const *seg, typename K::Line_2 const *line) : _seg(seg), _line(line), _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::Line_2 const * _line; mutable bool _known; mutable Intersection_results _result; mutable typename K::Point_2 _intersection_point; }; template inline bool do_intersect( const typename K::Segment_2 &p1, const typename K::Line_2 &p2, const K&) { typedef Segment_2_Line_2_pair pair_t; pair_t pair(&p1, &p2); return pair.intersection_type() != pair_t::NO_INTERSECTION; } template typename CGAL::Intersection_traits ::result_type intersection(const typename K::Segment_2 &seg, const typename K::Line_2 &line, const K&) { typedef Segment_2_Line_2_pair is_t; is_t ispair(&seg, &line); switch (ispair.intersection_type()) { case is_t::NO_INTERSECTION: default: return intersection_return(); case is_t::POINT: return intersection_return(ispair.intersection_point()); case is_t::SEGMENT: return intersection_return(seg); } } template typename CGAL::Intersection_traits ::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 inline bool do_intersect( const typename K::Line_2 &line, const typename K::Segment_2 &seg, const K& k) { return internal::do_intersect(seg, line, k); } template typename Segment_2_Line_2_pair::Intersection_results Segment_2_Line_2_pair::intersection_type() const { if (_known) return _result; // The non const this pointer is used to cast away const. _known = true; const typename K::Line_2 &l1 = _seg->supporting_line(); Line_2_Line_2_pair linepair(&l1, _line); switch ( linepair.intersection_type()) { case Line_2_Line_2_pair::NO_INTERSECTION: _result = NO_INTERSECTION; break; case Line_2_Line_2_pair::POINT: _intersection_point = linepair.intersection_point(); _result = (_seg->collinear_has_on(_intersection_point) ) ? POINT : NO_INTERSECTION; break; case Line_2_Line_2_pair::LINE: _result = SEGMENT; break; } return _result; } template typename K::Point_2 Segment_2_Line_2_pair::intersection_point() const { if (!_known) intersection_type(); CGAL_kernel_assertion(_result == POINT); return _intersection_point; } template typename K::Segment_2 Segment_2_Line_2_pair::intersection_segment() const { if (!_known) intersection_type(); CGAL_kernel_assertion(_result == SEGMENT); return *_seg; } } // namespace internal CGAL_INTERSECTION_FUNCTION(Segment_2, Line_2, 2) CGAL_DO_INTERSECT_FUNCTION(Segment_2, Line_2, 2) } //namespace CGAL #endif