Boost C++ Libraries

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/point.hpp>
#include <boost/geometry/geometries/box.hpp>

#include <boost/geometry/index/rtree.hpp>

// to store queries results
#include <vector>

// just for output
#include <iostream>
#include <boost/foreach.hpp>

namespace bg = boost::geometry;
namespace bgi = boost::geometry::index;

int main(void)
{
    typedef bg::model::point<float, 2, bg::cs::cartesian> point;
    typedef bg::model::box<point> box;
    typedef std::pair<box, unsigned> value;

    // create the rtree using default constructor
    bgi::rtree< value, bgi::quadratic<16> > rtree;

    // create some values
    for ( unsigned i = 0 ; i < 10 ; ++i )
    {
        // create a box
        box b(point(i, i), point(i + 0.5f, i + 0.5f));
        // insert new value
        rtree.insert(std::make_pair(b, i));
    }

    // find values intersecting some area defined by a box
    box query_box(point(0, 0), point(5, 5));
    std::vector<value> result_s;
    rtree.query(bgi::intersects(query_box), std::back_inserter(result_s));

    // find 5 nearest values to a point
    std::vector<value> result_n;
    rtree.query(bgi::nearest(point(0, 0), 5), std::back_inserter(result_n));

    // display results
    std::cout << "spatial query box:" << std::endl;
    std::cout << bg::wkt<box>(query_box) << std::endl;
    std::cout << "spatial query result:" << std::endl;
    BOOST_FOREACH(value const& v, result_s)
        std::cout << bg::wkt<box>(v.first) << " - " << v.second << std::endl;

    std::cout << "knn query point:" << std::endl;
    std::cout << bg::wkt<point>(point(0, 0)) << std::endl;
    std::cout << "knn query result:" << std::endl;
    BOOST_FOREACH(value const& v, result_n)
        std::cout << bg::wkt<box>(v.first) << " - " << v.second << std::endl;

    return 0;
}