Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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intersects (one geometry)

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

Synopsis

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

Parameters

Type

Concept

Name

Description

Geometry const &

Any type fulfilling a Geometry Concept

geometry

A model of the specified concept

Returns

Returns true if the geometry is self-intersecting

Header

Either

#include <boost/geometry/geometry.hpp>

Or

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

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>
#include <boost/geometry/domains/gis/io/wkt/wkt.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

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