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// Boost.Geometry (aka GGL, Generic Geometry Library)
// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
// Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_GEOMETRY_STRATEGIES_SIDE_INFO_HPP
#define BOOST_GEOMETRY_STRATEGIES_SIDE_INFO_HPP
#include <utility>
namespace boost { namespace geometry
{
/*!
\brief Class side_info: small class wrapping for sides (-1,0,1)
*/
class side_info
{
public :
inline side_info(int side_a1 = 0, int side_a2 = 0,
int side_b1 = 0, int side_b2 = 0)
{
sides[0].first = side_a1;
sides[0].second = side_a2;
sides[1].first = side_b1;
sides[1].second = side_b2;
}
template <int Which>
inline void set(int first, int second)
{
sides[Which].first = first;
sides[Which].second = second;
}
template <int Which, int Index>
inline void correct_to_zero()
{
if (Index == 0)
{
sides[Which].first = 0;
}
else
{
sides[Which].second = 0;
}
}
template <int Which, int Index>
inline int get() const
{
return Index == 0 ? sides[Which].first : sides[Which].second;
}
// Returns true if both lying on the same side WRT the other
// (so either 1,1 or -1-1)
template <int Which>
inline bool same() const
{
return sides[Which].first * sides[Which].second == 1;
}
inline bool collinear() const
{
return sides[0].first == 0
&& sides[0].second == 0
&& sides[1].first == 0
&& sides[1].second == 0;
}
inline bool crossing() const
{
return sides[0].first * sides[0].second == -1
&& sides[1].first * sides[1].second == -1;
}
inline bool touching() const
{
return (sides[0].first * sides[1].first == -1
&& sides[0].second == 0 && sides[1].second == 0)
|| (sides[1].first * sides[0].first == -1
&& sides[1].second == 0 && sides[0].second == 0);
}
template <int Which>
inline bool one_touching() const
{
// This is normally a situation which can't occur:
// If one is completely left or right, the other cannot touch
return one_zero<Which>()
&& sides[1 - Which].first * sides[1 - Which].second == 1;
}
inline bool meeting() const
{
// Two of them (in each segment) zero, two not
return one_zero<0>() && one_zero<1>();
}
template <int Which>
inline bool zero() const
{
return sides[Which].first == 0 && sides[Which].second == 0;
}
template <int Which>
inline bool one_zero() const
{
return (sides[Which].first == 0 && sides[Which].second != 0)
|| (sides[Which].first != 0 && sides[Which].second == 0);
}
inline bool one_of_all_zero() const
{
int const sum = std::abs(sides[0].first)
+ std::abs(sides[0].second)
+ std::abs(sides[1].first)
+ std::abs(sides[1].second);
return sum == 3;
}
template <int Which>
inline int zero_index() const
{
return sides[Which].first == 0 ? 0 : 1;
}
inline void debug() const
{
std::cout << sides[0].first << " "
<< sides[0].second << " "
<< sides[1].first << " "
<< sides[1].second
<< std::endl;
}
inline void reverse()
{
std::swap(sides[0], sides[1]);
}
//private :
std::pair<int, int> sides[2];
};
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_STRATEGIES_SIDE_INFO_HPP
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