Fw: Regular operations : intersection of two simple polygons

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Fw: Regular operations : intersection of two simple polygons

amit tripathi-2
Thanks for pointing the writting mistake . I am sending my problems again.

hi list
                                                         Thanks for response, i am attaching the test input file
p4.dat and source file simple_join_intersect.cpp . when i  run it under example  Boolean_set_operations_2  . i  got following output       

   floating point exception

(this is the test case when two polygons are touching)

 USAGE:executable inputfile
[root@localhost command_lineBoolean_set_operations_2]# ./simple_join_intersect p4.dat
Floating point exception
[root@localhost command_lineBoolean_set_operations_2]#



thanks alot








 

AMIT TRIPATHI
09836562804
M.Tech(C.S.)
I.S.I. KOLKATA

--- On Tue, 6/17/08, [hidden email] <[hidden email]> wrote:

From: [hidden email] <[hidden email]>
Subject: Re: [cgal-discuss] Minkowski'sum : offsetting a polygon
To: [hidden email]
Date: Tuesday, June 17, 2008, 3:51 PM

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" <[hidden email]>:

> &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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>


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p4.dat (76 bytes) Download Attachment
simple_join_intersect.cpp (3K) Download Attachment
print_utils.h (2K) Download Attachment