Boost C++ Libraries

Converts one geometry to another geometry.

Description

The convert algorithm converts one geometry, e.g. a BOX, to another geometry, e.g. a RING. This only works if it is possible and applicable. If the point-order is different, or the closure is different between two geometry types, it will be converted correctly by explicitly reversing the points or closing or opening the polygon rings.

Synopsis

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

Parameters

Header

Either

#include <boost/geometry.hpp>

Or

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

Conformance

The function convert is not defined by OGC.

Supported geometries

	Note
	In this status matrix above: columns are source types and rows are target types. So a box can be converted to a ring, polygon or multi-polygon, but not vice versa.

Complexity

Linear

Example

Shows how to convert a geometry into 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()
{
    typedef boost::geometry::model::d2::point_xy<double> point;
    typedef boost::geometry::model::box<point> box;
    typedef boost::geometry::model::polygon<point> polygon;

    point p1(1, 1);
    box bx = boost::geometry::make<box>(1, 1, 2, 2);

    // Assign a box to a polygon (conversion box->poly)
    polygon poly;
    boost::geometry::convert(bx, poly);

    // Convert a point to another point type (conversion of point-type)
    boost::tuple<double, double> p2;
    boost::geometry::convert(p1, p2); // source -> target

    using boost::geometry::dsv;
    std::cout
        << "box: " << dsv(bx) << std::endl
        << "polygon: " << dsv(poly) << 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

	Note
	convert is modelled as source -> target (where assign is modelled as target := source)