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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.
// 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)
//
// Custom triangle template Example
#include <iostream>
#include <boost/array.hpp>
#include <boost/tuple/tuple.hpp>
#include <boost/geometry/algorithms/area.hpp>
#include <boost/geometry/algorithms/centroid.hpp>
#include <boost/geometry/geometries/adapted/boost_tuple.hpp>
#include <boost/geometry/geometries/register/ring.hpp>
#include <boost/geometry/strategies/strategies.hpp>
#include <boost/geometry/io/dsv/write.hpp>
BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian)
template <typename P>
struct triangle : public boost::array<P, 3>
{
};
// Register triangle<P> as a ring
BOOST_GEOMETRY_REGISTER_RING_TEMPLATED(triangle)
namespace boost { namespace geometry { namespace dispatch {
// Specializations of area dispatch structure, implement algorithm
template<typename P, typename S>
struct area<ring_tag, triangle<P>, S>
{
static inline double apply(triangle<P> const& t, S const&)
{
return 0.5 * ((get<0>(t[1]) - get<0>(t[0])) * (get<1>(t[2]) - get<1>(t[0]))
- (get<0>(t[2]) - get<0>(t[0])) * (get<1>(t[1]) - get<1>(t[0])));
}
};
}}} // namespace boost::geometry::dispatch
int main()
{
//triangle<boost::geometry::point_xy<double> > t;
triangle<boost::tuple<double, double> > t;
t[0] = boost::make_tuple(0, 0);
t[1] = boost::make_tuple(5, 0);
t[2] = boost::make_tuple(2.5, 2.5);
std::cout << "Triangle: " << boost::geometry::dsv(t) << std::endl;
std::cout << "Area: " << boost::geometry::area(t) << std::endl;
//boost::geometry::point_xy<double> c;
boost::tuple<double, double> c;
boost::geometry::centroid(t, c);
std::cout << "Centroid: " << boost::geometry::dsv(c) << std::endl;
return 0;
}
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