// 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 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; }