Boost C++ Libraries

Assigns one geometry to another geometry.

Description

The assign algorithm assigns one geometry, e.g. a BOX, to another geometry, e.g. a RING. This only works if it is possible and applicable.

Synopsis

template<typename Geometry1, typename Geometry2>
void assign(Geometry1 & geometry1, Geometry2 const & geometry2)

Parameters

Header

Either

#include <boost/geometry.hpp>

Or

#include <boost/geometry/algorithms/assign.hpp>

Example

Shows how to assign a geometry from another geometry

#include <iostream>

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/box.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/adapted/boost_tuple.hpp>

BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian)

int main()
{
    using point = boost::geometry::model::d2::point_xy<double>;
    using box = boost::geometry::model::box<point>;
    using polygon = boost::geometry::model::polygon<point>;

    point p1;
    box b;
    boost::geometry::assign_values(p1, 1, 1);
    boost::geometry::assign_values(b, 1, 1, 2, 2);

    // Assign a box to a polygon (target = source)
    polygon p;
    boost::geometry::assign(p, b);

    // Assign a point to another point type (conversion of point-type)
    boost::tuple<double, double> p2;
    boost::geometry::assign(p2, p1);

    using boost::geometry::dsv;
    std::cout
        << "box: " << dsv(b) << std::endl
        << "polygon: " << dsv(p) << std::endl
        << "point: " << dsv(p1) << std::endl
        << "point tuples: " << dsv(p2) << std::endl
        ;

    return 0;
}

Output:

box: ((1, 1), (2, 2))
polygon: (((1, 1), (1, 2), (2, 2), (2, 1), (1, 1)))
point: (1, 1)
point tuples: (1, 1)

See also