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// Boost.Geometry (aka GGL, Generic Geometry Library)
// Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
// Copyright (c) 2008-2012 Barend Gehrels, Amsterdam, the Netherlands.
// 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_CARTESIAN_DISTANCE_PYTHAGORAS_HPP
#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_DISTANCE_PYTHAGORAS_HPP
#include <boost/geometry/core/access.hpp>
#include <boost/geometry/strategies/distance.hpp>
#include <boost/geometry/util/math.hpp>
#include <boost/geometry/util/calculation_type.hpp>
namespace boost { namespace geometry
{
namespace strategy { namespace distance
{
#ifndef DOXYGEN_NO_DETAIL
namespace detail
{
template <size_t I, typename T>
struct compute_pythagoras
{
template <typename Point1, typename Point2>
static inline T apply(Point1 const& p1, Point2 const& p2)
{
T const c1 = boost::numeric_cast<T>(get<I-1>(p1));
T const c2 = boost::numeric_cast<T>(get<I-1>(p2));
T const d = c1 - c2;
return d * d + compute_pythagoras<I-1, T>::apply(p1, p2);
}
};
template <typename T>
struct compute_pythagoras<0, T>
{
template <typename Point1, typename Point2>
static inline T apply(Point1 const&, Point2 const&)
{
return boost::numeric_cast<T>(0);
}
};
}
#endif // DOXYGEN_NO_DETAIL
namespace comparable
{
/*!
\brief Strategy to calculate comparable distance between two points
\ingroup strategies
\tparam Point1 \tparam_first_point
\tparam Point2 \tparam_second_point
\tparam CalculationType \tparam_calculation
*/
template <typename CalculationType = void>
class pythagoras
{
public :
template <typename Point1, typename Point2>
struct calculation_type
: util::calculation_type::geometric::binary
<
Point1,
Point2,
CalculationType,
double,
double
>
{};
template <typename Point1, typename Point2>
static inline typename calculation_type<Point1, Point2>::type
apply(Point1 const& p1, Point2 const& p2)
{
BOOST_CONCEPT_ASSERT( (concepts::ConstPoint<Point1>) );
BOOST_CONCEPT_ASSERT( (concepts::ConstPoint<Point2>) );
// Calculate distance using Pythagoras
// (Leave comment above for Doxygen)
assert_dimension_equal<Point1, Point2>();
return detail::compute_pythagoras
<
dimension<Point1>::value,
typename calculation_type<Point1, Point2>::type
>::apply(p1, p2);
}
};
} // namespace comparable
/*!
\brief Strategy to calculate the distance between two points
\ingroup strategies
\tparam CalculationType \tparam_calculation
\qbk{
[heading Notes]
[note Can be used for points with two\, three or more dimensions]
[heading See also]
[link geometry.reference.algorithms.distance.distance_3_with_strategy distance (with strategy)]
}
*/
template
<
typename CalculationType = void
>
class pythagoras
{
public :
template <typename P1, typename P2>
struct calculation_type
: util::calculation_type::geometric::binary
<
P1,
P2,
CalculationType,
double,
double // promote integer to double
>
{};
/*!
\brief applies the distance calculation using pythagoras
\return the calculated distance (including taking the square root)
\param p1 first point
\param p2 second point
*/
template <typename P1, typename P2>
static inline typename calculation_type<P1, P2>::type
apply(P1 const& p1, P2 const& p2)
{
// The cast is necessary for MSVC which considers sqrt __int64 as an ambiguous call
return math::sqrt
(
boost::numeric_cast<typename calculation_type<P1, P2>::type>
(
comparable::pythagoras<CalculationType>::apply(p1, p2)
)
);
}
};
#ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
namespace services
{
template <typename CalculationType>
struct tag<pythagoras<CalculationType> >
{
typedef strategy_tag_distance_point_point type;
};
template <typename CalculationType, typename P1, typename P2>
struct return_type<distance::pythagoras<CalculationType>, P1, P2>
: pythagoras<CalculationType>::template calculation_type<P1, P2>
{};
template <typename CalculationType>
struct comparable_type<pythagoras<CalculationType> >
{
typedef comparable::pythagoras<CalculationType> type;
};
template <typename CalculationType>
struct get_comparable<pythagoras<CalculationType> >
{
typedef comparable::pythagoras<CalculationType> comparable_type;
public :
static inline comparable_type apply(pythagoras<CalculationType> const& )
{
return comparable_type();
}
};
template <typename CalculationType, typename Point1, typename Point2>
struct result_from_distance<pythagoras<CalculationType>, Point1, Point2>
{
private :
typedef typename return_type<pythagoras<CalculationType>, Point1, Point2>::type return_type;
public :
template <typename T>
static inline return_type apply(pythagoras<CalculationType> const& , T const& value)
{
return return_type(value);
}
};
// Specializations for comparable::pythagoras
template <typename CalculationType>
struct tag<comparable::pythagoras<CalculationType> >
{
typedef strategy_tag_distance_point_point type;
};
template <typename CalculationType, typename P1, typename P2>
struct return_type<comparable::pythagoras<CalculationType>, P1, P2>
: comparable::pythagoras<CalculationType>::template calculation_type<P1, P2>
{};
template <typename CalculationType>
struct comparable_type<comparable::pythagoras<CalculationType> >
{
typedef comparable::pythagoras<CalculationType> type;
};
template <typename CalculationType>
struct get_comparable<comparable::pythagoras<CalculationType> >
{
typedef comparable::pythagoras<CalculationType> comparable_type;
public :
static inline comparable_type apply(comparable::pythagoras<CalculationType> const& )
{
return comparable_type();
}
};
template <typename CalculationType, typename Point1, typename Point2>
struct result_from_distance<comparable::pythagoras<CalculationType>, Point1, Point2>
{
private :
typedef typename return_type<comparable::pythagoras<CalculationType>, Point1, Point2>::type return_type;
public :
template <typename T>
static inline return_type apply(comparable::pythagoras<CalculationType> const& , T const& value)
{
return_type const v = value;
return v * v;
}
};
template <typename Point1, typename Point2>
struct default_strategy
<
point_tag, point_tag, Point1, Point2, cartesian_tag, cartesian_tag
>
{
typedef pythagoras<> type;
};
} // namespace services
#endif // DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
}} // namespace strategy::distance
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_DISTANCE_PYTHAGORAS_HPP
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