CGAL users discussion list

I have to admit that a more extensive example would help here, and we  
do consider enhancing the existing one for the next release. In the  
mean time, the offset polygon is an object of type  
Traits::General_polygon_with_holes_2, which models the concept  
GeneralPolygonWithHoles_2  
<http://www.cgal.org/Manual/3.3/doc_html/cgal_manual/Boolean_set_operations_2_ref/Concept_GeneralPolygonWithHoles_2.html#Cross_link_anchor_726>. Consult the manual for the relevant valid expressions involving a model of this concept. In short you can obtain the outer boundary of type Traits::Polygon_2, and traverse the holes to obtain objects of the same type. You can obtain the curves that comprise the boundaries of these objects using the traits function-object  
Traits::Construct_curves_2.

The regularized intersection of 2 polygons that share a vertex or an  
edge is empty. In other words they do not intersect. However you are  
not suppose to get a floating point exception under any circumstances  
(assuming you use exact arithmetic, etc). If you do, it might be a  
bug, and we would like to get a short test case that reproduces it.

Quoting "amit tripathi" 
<>:

> &nbsp;
> &nbsp;
> Hi list.....
> &nbsp;
> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; i am learning/using CGAL ........by examples given in library...........i have following  
> questions&nbsp;...........
> &nbsp;
> 1) how to find output of Minkowski sum of a cicle of given radius  
> and a simple polygon.............in examples ...offsetting  
> polygon......it is not given that how to get print of  
> offset...................i dont know how this object is stored.....
> &nbsp;
> &nbsp;
> &nbsp;
> 2) Boolean operations supported by CGAL are regular so
> &nbsp;
>
> &nbsp;when I was designing test cases for polygon intersection code  
> …………I found that code has some problem in the &nbsp;execution for  
> the cases…
> 1)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; P int Q ={(x,y)}
> 2)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; P int Q ={(x,y)&nbsp; : y=mx+c}
> 3)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; P int Q = null
> &nbsp;
> &nbsp;
> But when I put check for the case P int Q =null …..then for the  
> three cases I got corresponding outputs as follows……
> 1)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Floating point exception
> 2)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Do not intersect
> 3)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Do not intersect
> &nbsp;
> Which is not consistent….to situation ………
> &nbsp;
> Is there any way to get ordinary intersection that can resolve above  
> problems...............the problem may be solved if we know how  
> polygons are stored then check for same vertices in both the  
> polygons.......
> &nbsp;
> Even if i am trying to find the Minkowski sum of P and Q
> (as described in Minkowski_sum_2) .............i faced problem for  
> the above three cases..........................
> &nbsp;
> &nbsp;
> plz try to help me ............my assignment submission date is near....
> &nbsp;
> thanks for all........
> &nbsp;
> &nbsp;
>
> AMIT TRIPATHI
> 09836562804
> M.Tech(C.S.)
> I.S.I. KOLKATA
>
>
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