| Home | Libraries | People | FAQ | More

#### convert

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 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

Type | Concept | Name | Description
--- | --- | --- | ---
Geometry1 const & | Any type fulfilling a Geometry Concept | geometry1 | A model of the specified concept (source)
Geometry2 & | Any type fulfilling a Geometry Concept | geometry2 | A model of the specified concept (target)

###### Header

Either

`#include <boost/geometry/geometry.hpp>`

Or

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

###### Conformance

The function convert is not defined by OGC.

###### Supported geometries

| Point | Segment | Box | Linestring | Ring | Polygon | MultiPoint | MultiLinestring | MultiPolygon
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Point |  |  |  |  |  |  |  |  |
Segment |  |  |  |  |  |  |  |  |
Box |  |  |  |  |  |  |  |  |
Linestring |  |  |  |  |  |  |  |  |
Ring |  |  |  |  |  |  |  |  |
Polygon |  |  |  |  |  |  |  |  |
MultiPoint |  |  |  |  |  |  |  |  |
MultiLinestring |  |  |  |  |  |  |  |  |
MultiPolygon |  |  |  |  |  |  |  |  |

| 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

- assign

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