// Copyright (c) 1998 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.
//
// $Source: /CVSROOT/CGAL/Packages/Distance_2/include/CGAL/squared_distance_utils.h,v $
// $Revision: 1.11 $ $Date: 2003/10/21 12:15:22 $
// $Name: $
//
// Author(s) : Geert-Jan Giezeman
#ifndef CGAL_SQUARED_DISTANCE_UTILS_H
#define CGAL_SQUARED_DISTANCE_UTILS_H
#include <CGAL/determinant.h>
#include <CGAL/wmult.h>
CGAL_BEGIN_NAMESPACE
namespace CGALi {
template <class K>
bool is_null(const typename K::Vector_2 &v, const K&)
{
typedef typename K::RT RT;
return v.hx()==RT(0) && v.hy()==RT(0);
}
template <class K>
typename K::RT
wdot(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K&)
{
return (u.hx()*v.hx() + u.hy()*v.hy());
}
template <class K>
typename K::RT wdot_tag(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K&,
const Cartesian_tag&)
{
return (p.x() - q.x()) * (r.x() - q.x())
+ (p.y() - q.y()) * (r.y() - q.y());
}
template <class K>
typename K::RT wdot_tag(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K&,
const Homogeneous_tag&)
{
return (p.hx() * q.hw() - q.hx() * p.hw())
* (r.hx() * q.hw() - q.hx() * r.hw())
+ (p.hy() * q.hw() - q.hy() * p.hw())
* (r.hy() * q.hw() - q.hy() * r.hw());
}
template <class K>
typename K::RT wdot(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K& k)
{
typedef typename K::Kernel_tag Tag;
Tag tag;
return wdot_tag(p, q, r, k, tag);
}
template <class K>
typename K::RT
wcross(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K&)
{
return (typename K::RT)(u.hx()*v.hy() - u.hy()*v.hx());
}
template <class K>
inline
typename K::RT
wcross_tag(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K&,
const Homogeneous_tag&)
{
return det3x3_by_formula(
p.hx(), q.hx(), r.hx(),
p.hy(), q.hy(), r.hy(),
p.hw(), q.hw(), r.hw());
}
template <class K>
inline
typename K::FT
wcross_tag(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K&,
const Cartesian_tag&)
{
return (q.x()-p.x())*(r.y()-q.y()) - (q.y()-p.y())*(r.x()-q.x());
}
template <class K>
typename K::RT wcross(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K& k)
{
typedef typename K::Kernel_tag Tag;
Tag tag;
return wcross_tag(p, q, r, k, tag);
}
template <class K>
inline bool is_acute_angle(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
return RT(wdot(u, v, k)) > RT(0) ;
}
template <class K>
inline bool is_straight_angle(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
return RT(wdot(u, v, k)) == RT(0) ;
}
template <class K>
inline bool is_obtuse_angle(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
return RT(wdot(u, v, k)) < RT(0) ;
}
template <class K>
inline bool is_acute_angle(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K& k)
{
typedef typename K::RT RT;
return RT(wdot(p, q, r, k)) > RT(0) ;
}
template <class K>
inline bool is_straight_angle(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K& k)
{
typedef typename K::RT RT;
return RT(wdot(p, q, r, k)) == RT(0) ;
}
template <class K>
inline bool is_obtuse_angle(const typename K::Point_2 &p,
const typename K::Point_2 &q,
const typename K::Point_2 &r,
const K& k)
{
typedef typename K::RT RT;
return RT(wdot(p, q, r, k)) < RT(0) ;
}
template <class K>
Orientation orientation(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
RT wcr = wcross(u,v, k);
return (wcr > RT(0)) ? COUNTERCLOCKWISE :
(wcr < RT(0)) ? CLOCKWISE
: COLLINEAR;
}
template <class K>
inline bool counterclockwise(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
return RT(wcross(u,v, k)) > RT(0);
}
template <class K>
inline bool left_turn(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
return RT(wcross(u,v, k)) > RT(0);
}
template <class K>
inline bool clockwise(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
return RT(wcross(u,v, k)) < RT(0);
}
template <class K>
inline bool right_turn(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
return RT(wcross(u,v, k)) < RT(0);
}
template <class K>
inline bool collinear(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::RT RT;
return RT(wcross(u,v, k)) == RT(0);
}
/*
the ordertype, right_turn, left_turn and collinear routines for points are
defined elsewhere.
*/
template <class K>
inline
bool
same_direction_tag(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K&,
const Cartesian_tag&)
{
typedef typename K::FT FT;
const FT& ux = u.x();
const FT& uy = u.y();
if (CGAL_NTS abs(ux) > CGAL_NTS abs(uy)) {
return CGAL_NTS sign(ux) == CGAL_NTS sign(v.x());
} else {
return CGAL_NTS sign(uy) == CGAL_NTS sign(v.y());
}
}
template <class K>
inline
bool
same_direction_tag(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K&,
const Homogeneous_tag&)
{
typedef typename K::RT RT;
const RT& uhx = u.hx();
const RT& uhy = u.hy();
if (CGAL_NTS abs(uhx) > CGAL_NTS abs(uhy)) {
return CGAL_NTS sign(uhx) == CGAL_NTS sign(v.hx());
} else {
return CGAL_NTS sign(uhy) == CGAL_NTS sign(v.hy());
}
}
template <class K>
inline
bool
same_direction(const typename K::Vector_2 &u,
const typename K::Vector_2 &v,
const K& k)
{
typedef typename K::Kernel_tag Tag;
Tag tag;
return same_direction_tag(u,v, k, tag);
}
} // namespace CGALi
CGAL_END_NAMESPACE
#endif // CGAL_SQUARED_DISTANCE_UTILS_H
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