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// Copyright (c) 1999 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-3.5-branch/Homogeneous_kernel/include/CGAL/Homogeneous/basic_constructionsH2.h $
// $Id: basic_constructionsH2.h 28567 2006-02-16 14:30:13Z lsaboret $
//
//
// Author(s) : Sven Schoenherr
// Stefan Schirra
#ifndef CGAL_BASIC_CONSTRUCTIONSH2_H
#define CGAL_BASIC_CONSTRUCTIONSH2_H
#include <CGAL/Homogeneous/PointH2.h>
#include <CGAL/Homogeneous/LineH2.h>
CGAL_BEGIN_NAMESPACE
template <class R>
CGAL_KERNEL_MEDIUM_INLINE
typename R::Point_2
gp_linear_intersection(const LineH2<R>& l1, const LineH2<R>& l2)
{
return typename R::Point_2( l1.b()*l2.c() - l2.b()*l1.c(),
l2.a()*l1.c() - l1.a()*l2.c(),
l1.a()*l2.b() - l2.a()*l1.b() );
}
template <class R>
CGAL_KERNEL_MEDIUM_INLINE
typename R::FT
squared_distance( const PointH2<R>& p, const PointH2<R>& q )
{
typedef typename R::RT RT;
typedef typename R::FT FT;
const RT & phx = p.hx();
const RT & phy = p.hy();
const RT & phw = p.hw();
const RT & qhx = q.hx();
const RT & qhy = q.hy();
const RT & qhw = q.hw();
RT sq_dist_numerator =
phx * phx * qhw * qhw
- RT(2) * phx * qhx * phw * qhw
+ qhx * qhx * phw * phw
+ phy * phy * qhw * qhw
- RT(2) * phy * qhy * phw * qhw
+ qhy * qhy * phw * phw ;
RT sq_dist_denominator = qhw * qhw * phw * phw ;
return FT( sq_dist_numerator ) / FT( sq_dist_denominator );
}
CGAL_END_NAMESPACE
#endif // CGAL_BASIC_CONSTRUCTIONSH2_H
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