mirror of https://github.com/CGAL/cgal
99 lines
3.5 KiB
C++
99 lines
3.5 KiB
C++
// Copyright (c) 1999 Utrecht University (The Netherlands),
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// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
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// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
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// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
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// and Tel-Aviv University (Israel). All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; version 2.1 of the License.
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// See the file LICENSE.LGPL distributed with CGAL.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $Source$
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// $Revision$ $Date$
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// $Name$
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//
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// Author(s) : Susan Hert
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#ifndef CGAL_PREDICATES_ON_SEGMENTSH2_H
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#define CGAL_PREDICATES_ON_SEGMENTSH2_H
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#include <CGAL/Homogeneous/SegmentH2.h>
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#include <CGAL/Homogeneous/predicates_on_pointsH2.h>
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CGAL_BEGIN_NAMESPACE
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template <class R>
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CGAL_KERNEL_MEDIUM_INLINE
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Comparison_result
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compare_slopes(const SegmentH2<R>& s1, const SegmentH2<R>& s2)
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{
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typedef typename R::FT FT;
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Comparison_result cmp_y1 = compare_y(s1.source(), s1.target());
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if (cmp_y1 == EQUAL) // horizontal
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{
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Comparison_result cmp_x2 = compare_x(s2.source(), s2.target());
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if (cmp_x2 == EQUAL) return SMALLER;
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FT s_hw = s2.source().hw();
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FT t_hw = s2.target().hw();
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return Comparison_result (
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- CGAL_NTS sign((s2.source().hy()*t_hw - s2.target().hy()*s_hw) *
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(s2.source().hx()*t_hw - s2.target().hx()*s_hw)) );
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}
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Comparison_result cmp_y2 = compare_y(s2.source(), s2.target());
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if (cmp_y2 == EQUAL)
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{
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Comparison_result cmp_x1 = compare_x(s1.source(), s1.target());
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if (cmp_x1 == EQUAL) return LARGER;
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FT s_hw = s1.source().hw();
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FT t_hw = s1.target().hw();
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return Comparison_result (
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CGAL_NTS sign((s1.source().hy()*t_hw - s1.target().hy()*s_hw) *
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(s1.source().hx()*t_hw - s1.target().hx()*s_hw)) );
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}
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Comparison_result cmp_x1 = compare_x(s1.source(), s1.target());
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Comparison_result cmp_x2 = compare_x(s2.source(), s2.target());
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if (cmp_x1 == EQUAL)
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return cmp_x2 == EQUAL ? EQUAL : LARGER;
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if (cmp_x2 == EQUAL) return SMALLER;
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FT s1_s_hw = s1.source().hw();
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FT s1_t_hw = s1.target().hw();
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FT s2_s_hw = s2.source().hw();
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FT s2_t_hw = s2.target().hw();
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FT s1_xdiff = s1.source().hx()*s1_t_hw - s1.target().hx()*s1_s_hw;
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FT s1_ydiff = s1.source().hy()*s1_t_hw - s1.target().hy()*s1_s_hw;
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FT s2_xdiff = s2.source().hx()*s2_t_hw - s2.target().hx()*s2_s_hw;
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FT s2_ydiff = s2.source().hy()*s2_t_hw - s2.target().hy()*s2_s_hw;
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Sign s1_sign = CGAL_NTS sign(s1_ydiff * s1_xdiff);
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Sign s2_sign = CGAL_NTS sign(s2_ydiff * s2_xdiff);
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if (s1_sign < s2_sign) return SMALLER;
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if (s1_sign > s2_sign) return LARGER;
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if (s1_sign > 0)
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return Comparison_result(
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CGAL_NTS sign ( CGAL_NTS abs(s1_ydiff * s2_xdiff) -
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CGAL_NTS abs(s2_ydiff * s1_xdiff)) );
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return Comparison_result(
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CGAL_NTS sign ( CGAL_NTS abs(s2_ydiff * s1_xdiff) -
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CGAL_NTS abs(s1_ydiff * s2_xdiff)) );
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}
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CGAL_END_NAMESPACE
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#endif // CGAL_PREDICATES_ON_SEGMENTSH2_H
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