geometry/example/c04_b_custom_triangle_example.cpp at develop · boostorg/geometry · GitHub

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// Boost.Geometry (aka GGL, Generic Geometry Library)

// 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 <array>

#include <iostream>

#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 std::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 Point>

struct area<triangle<Point>, ring_tag>

{

template <typename Strategy>

static inline double apply(triangle<Point> const& t, Strategy 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;

}

geometry/example/c04_b_custom_triangle_example.cpp at develop · boostorg/geometry · GitHub

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