Hi, <br><br>I&#39;m trying to clip line segments using boost polygon.<br>Boost polygon does not provide public interface but somehow I find the function validate_scan(),<br>which can do the line clipping.<br><br><br>My input are two segments  &lt; (10, 10), (10, 2),  0 &gt;<br>

                              <div id=":10n">           &lt; (  6,   7), (11, 2), 1 &gt;<br><br>The numbers in the brackets are coordinates of two end points of the segments and the number after it is the segment id.<br>
So it looks like this.<br>
<br><br>The result I expect should be four segments, which are the result of intersection &lt;(10,10), (10,3), 0&gt;<br>                                                                                                                   &lt;(10,3),   (10,2), 0&gt;<br>

                                                                                                                   &lt;(6,7  ),   (10,3), 1&gt;<br>                                                                                                                   &lt;(10,3),   (11, 2), 1&gt;<br>

<br>However, the &lt;(10,3), (11,2), 1&gt; segment is replace by two 
segments, which are &lt;(10,3), (10,2), 1&gt; and &lt;(10,2), (11,2), 
1&gt;.<br><br>Can someone tell me what happened? Replacing the segment with the other two are not right behavior.<br>
<br>Thank you very much.<div class="yj6qo ajU"><div id=":11o" class="ajR" tabindex="0"><img class="ajT" src="https://mail.google.com/mail/images/cleardot.gif"></div></div></div><br clear="all"><br>-- <br>Jian Hu<br><br>