Boost C++ Libraries

Checks if a geometry has at least one intersection (crossing or self-tangency)

Synopsis

template<typename Geometry>
bool intersects(Geometry const & geometry)

Parameters

Returns

Returns true if the geometry is self-intersecting

Header

Either

#include <boost/geometry.hpp>

Or

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

Conformance

The function intersects implements function Intersects from the OGC Simple Feature Specification.

The version with one parameter is additional and not described in the OGC standard

Examples

Check if two linestrings intersect each other

#include <iostream>

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/linestring.hpp>
#include <boost/geometry/geometries/point_xy.hpp>

int main()
{
    // Calculate the intersects of a cartesian polygon
    typedef boost::geometry::model::d2::point_xy<double> P;
    boost::geometry::model::linestring<P> line1, line2;

    boost::geometry::read_wkt("linestring(1 1,2 2,3 3)", line1);
    boost::geometry::read_wkt("linestring(2 1,1 2,4 0)", line2);

    bool b = boost::geometry::intersects(line1, line2);

    std::cout << "Intersects: " << (b ? "YES" : "NO") << std::endl;

    return 0;
}

Output:

Intersects: YES