我正在尝试使用boost geometry方法Intersects和我自己的point类，该类已成功注册到boost geometry库。

boost文档(https://www.boost.org/doc/libs/1-73_0/libs/geometry/doc/html/geometry/reference/algorithms/intersection/intersection3.html)说明我可以使用点的矢量作为输出参数。 所以我写了这个:

#include <iostream>
#include <deque>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/register/point.hpp>

namespace bg = boost::geometry;
using namespace std;

class cxy
{
public:
    double x;
    double y;
    cxy( double X, double Y )
        : x( X )
        , y( Y )
    {

    }
    /// boost geometry insists on a default constructor
    cxy()
        : cxy(0,0)
    {

    }
};

BOOST_GEOMETRY_REGISTER_POINT_2D( cxy, double, bg::cs::cartesian, x, y )
typedef bg::model::segment<cxy> segment_t;

int main()
{
    cxy a(0,0);
    cxy b(1,1);
    cxy c(1,0);
    cxy d(0,1) ;

    std::vector<cxy> out;

    //////////////// this compiles

    bg::intersection(segment_t{a, b}, segment_t{c, d}, out);

    //////////////// this does not!!!

    segment_t ab( a, b );
    segment_t cd( c, d );
    bg::intersects( ab, cd, out );

    return 0;
}

需要说明的是:我的问题是混淆了交集和交集

下面的代码编译并生成预期的结果:

#include <iostream>
#include <deque>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/register/point.hpp>

namespace bg = boost::geometry;
using namespace std;

class cxy
{
public:
    double x;
    double y;
    cxy( double X, double Y )
        : x( X )
        , y( Y )
    {

    }
    /// boost geometry insists on a default constructor
    cxy()
        : cxy(0,0)
    {

    }
};

BOOST_GEOMETRY_REGISTER_POINT_2D( cxy, double, bg::cs::cartesian, x, y )
typedef bg::model::segment<cxy> segment_t;

int main()
{
    cxy a(0,0);
    cxy b(1,1);
    cxy c(1,0);
    cxy d(0,1) ;

    segment_t ab( a, b );
    segment_t cd( c, d );
    std::vector<cxy> out;
    if( ! bg::intersection( ab, cd, out ) ) {
       std::cout << "no intersection\n";
       return 1;
    }
    std::cout << "intersection at " << out[0].x <<" " << out[0].y << "\n";

    return 0;
}