Hi Tanaka,

(the policy of this list is to avoid top-postings)

On 20-8-2013 16:30, Tanaka Simon wrote:

- assume we have an intersection point C of a polygon with a segment/linestring. C lies on the segment defined by the pair of points A and B, which are stored in the polygon. is it possible to return A and B, not only C?

Yes, internally the get_turns method has a lot more information, a.o. a segment_identifier which indicate exactly the segment on the polygon (so indirectly also A/B). It is a method in namespace detail::, so not documented and it might ever change, but basically it is usable.
But intersection does not return this information indeed.

- is it possible to have a polygon made of segment, something like boost::geometry::model::polygon< segment > ?

questions not directly related to the thread's question, but related to the attached code (should i start a new topic?):
- i use a custom point class myPoint. how to register the getter and setter template methods (e.g. get<0>)?

Specify just get<0> indeed. Works for me (using clang).
If this does not work, for some reason or compiler, you can use boost::geometry::traits to register your point-type. You are not using a macro then, writing some more lines code, but you get much more flexibility then. See e.g. example c05_custom_point_pointer_example.cpp where this is done.

- can i register std::shared_ptr<myPoint> instead of myPoint?

That is (basically) not necessary, because all access to points is equivalent between values, references and pointers. However, that is enabled for pointers, but not (yet) for shared points. I did not try it, but probably won't work. We use boost::is_pointer to check if it is a pointer - that returns probably false for shared_ptr (though I'm not sure). It should be possible to enable this for Boost.Geometry too in the future.

- why is boost::geometry::model::polygon< std::shared_ptr<point> > not working?

Because of the same reason. You can use polygon<point_pointer>, see the same c05 exampe.

Regards, Barend