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Converts one geometry to another geometry.
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.
template<typename Geometry1, typename Geometry2> void convert(Geometry1 const & geometry1, Geometry2 & geometry2)
| 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) | 
Either
          #include <boost/geometry.hpp>
        
Or
          #include <boost/geometry/algorithms/convert.hpp>
        
The function convert is not defined by OGC.
| Point | Segment | Box | Linestring | Ring | Polygon | MultiPoint | MultiLinestring | MultiPolygon | |
|---|---|---|---|---|---|---|---|---|---|
| Point | 
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| Segment | 
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| Box | 
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| Linestring | 
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| Ring | 
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| Polygon | 
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| MultiPoint | 
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| MultiLinestring | 
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| MultiPolygon | 
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| ![[Note]](../../../../../../../doc/src/images/note.png) | Note | 
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| 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. | 
Linear
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)
| ![[Note]](../../../../../../../doc/src/images/note.png) | Note | 
|---|---|
| convert is modelled as source -> target (where assign is modelled as target := source) |