[Boost-users] How to do line clipping using boost polygon?

Subject: [Boost-users] How to do line clipping using boost polygon?
From: jian hu (andy.hujian_at_[hidden])
Date: 2012-10-16 16:34:03

Hi,

I'm trying to clip line segments using boost polygon.
Boost polygon does not provide public interface but somehow I find the
function validate_scan(),
which can do the line clipping.

My input are two segments  < (10, 10), (10, 2),  0 >

           < (  6,   7), (11, 2), 1 >

The numbers in the brackets are coordinates of two end points of the
segments and the number after it is the segment id.
So it looks like this.

The result I expect should be four segments, which are the result of
intersection <(10,10), (10,3), 0>

                                       <(10,3),   (10,2), 0>

<(6,7  ),   (10,3), 1>

                                       <(10,3),   (11, 2), 1>

However, the <(10,3), (11,2), 1> segment is replace by two segments, which
are <(10,3), (10,2), 1> and <(10,2), (11,2), 1>.

Can someone tell me what happened? Replacing the segment with the other two
are not right behavior.

Thank you very much.

-- 
Jian Hu