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["peter heppel" <>]

Team

It's quite straightforward to compute the centroid of a polygon using the 
CGAL functions to triangulate and to calculate the centroid of a triangle. 
If you like you can work from my code for this

P

-----Original Message-----
From: Andreas Fabri 
[mailto:]
 
Sent: 25 November 2007 18:44
To: 

Subject: Re: [cgal-discuss] center of a given polygon in CGAL


I think what I wrote is wrong. We have a function to compute the
centroid of points, but that wouldn't give you the centroid of
a polygon.

Imagine you have an equilateral triangle with additional
points on one edge. The additional points would pull the
centroid towards the edge, although the triangle is unchanged.

andreas


Alejandro M. Aragón wrote:
> I think there should be a link to that in the Polygon documentation page
> because I also tried to find it in the Polygon_2 class and I ended up
> implementing my own function.
> 
> Regards,
> 
> a²
> 
> On Sun, 2007-11-25 at 07:58 -0800, Mahmood NT wrote:
>> Thanks for info, I was looking in polygon section
>>  
>> Mahmood NT
>>
>>
>> ----- Original Message ----
>> From: Andreas Fabri 
>> <>
>> To: 
>> 
>> Sent: Sunday, November 25, 2007 4:31:48 PM
>> Subject: Re: [cgal-discuss] center of a given polygon in CGAL
>>
>> Mahmood NT wrote:
>>> I think it a good idea to add a function for computing the center of
>> a 
>>> given polygon (centre of gravity). 
>> It's already provided:
>>
>> http://www.cgal.org/Manual/3.3/doc_html/cgal_manual/Principal_component_analysis_ref/Function_barycenter.html#Cross_link_anchor_1303
>>
>>
>> there is a good illustration at
>>> http://local.wasp.uwa.edu.au/~pbourke/geometry/polyarea/ 
>>> <http://local.wasp.uwa.edu.au/%7Epbourke/geometry/polyarea/> about
>> how 
>>> to compute centroid of a polygon. The list of functions I saw
>> related to 
>>> polygon section, are:
>>> CGAL::area_2
>>> CGAL::bbox_2
>>> CGAL::bottom_vertex_2
>>> CGAL::bounded_side_2
>>> CGAL::is_convex_2
>>> CGAL::is_simple_2
>>> CGAL::left_vertex_2
>>> CGAL::orientation_2
>>> CGAL::oriented_side_2
>>> CGAL::polygon_area_2
>>> CGAL::right_vertex_2
>>> CGAL::top_vertex_2
>>> / 
>>>
>> <http://www.cgal.org/Manual/3.3/doc_html/cgal_manual/Polygon_ref/Function_area_2.html#Cross_link_anchor_658>
>>> /I am not expert in coding with CGAL style, but I think it is not
>> hard 
>>> for CGAL developers that implement more difficult algorithms.
>>>  
>>> *Mahmood NT*
>>>
>>>
>>>
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