CGAL::intersection error

Question

i am using CGAL to calculate intersections between 3d triangles. I need to verify if the intersections return points or lines or triangles.

typedef CGAL::Cartesian<double> tc;
typedef tc::Triangle_3       Triangle3;

CGAL::cpp11::result_of<tc::Intersect_3(Triangle3,Triangle3)>::type
                resultL1 = CGAL::intersection(*t_3,*tLado1_3);

if (resultL1){                                              // LINE 110
   boost::apply_visitor(Intersection_visitor(), *resultL1); // LINE 111
}

Intersection visitor:

template<typename R>
struct Intersection_visitor {
    typedef void result_type;
    void operator()(const Point3<R>& p) const{
        // handle point
    }
    void operator()(const Segment_3<R>& s) const{
    // handle segment
    }
    void operator()(const Triangle3<R>& t) const{
    // handle triangle
    }
};

This is giving me two erros:

TextureManager.cpp:110: error: invalid type argument of unary '*' (have 'bool')

and

TextureManager.cpp:111: error: could not convert 'resultL1' from 'CGAL::cpp11::result_of<CGAL::CommonKernelFunctors::Intersect_3<CGAL::Cartesian<double> >(CGAL::Triangle_3<CGAL::Cartesian<double> >, CGAL::Triangle_3<CGAL::Cartesian<double> >)>::type {aka CGAL::Object}' to 'bool'

Does someone knoe how to fix these?

Answer 1

According to the manual page you are missing a possible type for the operator() in the visitor. The following example compiles fine.

#include <CGAL/Cartesian.h>

typedef CGAL::Cartesian<double> tc;
typedef tc::Triangle_3       Triangle3;

template<typename R>
struct Intersection_visitor {
    typedef void result_type;
    void operator()(const CGAL::Point_3<R>& /* p */) const{
        // handle point
    }
    void operator()(const CGAL::Segment_3<R>& /* s */) const{
    // handle segment
    }
    void operator()(const CGAL::Triangle_3<R>& /* t */) const{
    // handle triangle
    }
    void operator()(const std::vector< CGAL::Point_3<R> >& /* t */) const{
    // handle triangle
    }
};

int main()
{
  Triangle3 t1, t2;
  CGAL::cpp11::result_of<tc::Intersect_3(Triangle3,Triangle3)>::type
                  resultL1 = CGAL::intersection(t1, t2);


  if (resultL1){                                              // LINE 110
     boost::apply_visitor(Intersection_visitor<tc>(), *resultL1); // LINE 111
  }

}