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[Bryant <>]

Thank you for your reply!

You were correct that I meant:

> The above code results in poly_set containing 
/*
> a polygon with holes with the following outer boundary
*/
I'm still surprised that I never came across this fact while reading the
docs.

Nevertheless, do you know of a /built-in/ way of converting a relatively
simple polygon into a list of simple ones? I'm not finding anything online.


Efi Fogel wrote
> I haven't tested it myself, but if you meant to say:
> 
> The above code results in poly_set containing *a polygon with holes with
> the following outer boundary*:
> (0, 1), (1, 1), (1, 0), (2, 0), (2, 1), (1, 1), (1, 2), (0, 2)
> 
> Then there is no problem, cause according to the rules the boundary is a
> relatively simple polygon; see
> https://doc.cgal.org/latest/Boolean_set_operations_2/index.html
>    ____  _        ____             _
>   /_____/_) o    /__________  __  //
>  (____ (   (    (    (_/ (_/-(-'_(/
>                          _/
> 
> 
> 
> 
> On Wed, 20 Feb 2019 at 06:17, Bryant <

> bryantcurto@

> > wrote:
> 
>> When taking the difference between a /simple/ Polygon_set_2 and a
>> /simple/
>> Polygon_2, the result may be non-simple. This appears to occur when one
>> would expect the difference to result in two polygons with holes that
>> share
>> a point.
>>
>> I use the following definitions:
>> - A Polygon_set_2 is simple if the Polygon_with_holes_2s composing it are
>> simple.
>> - A Polygon_with_holes_2 is simple if its outer boundary and holes are
>> simple.
>>
>> Here's a minimum working example:
>>         CGAL::Polygon_2
> <K>
>  poly1;
>>         poly1.push_back(CGAL::Point_2
> <K>
> (0, 0));
>>         poly1.push_back(CGAL::Point_2
> <K>
> (2, 0));
>>         poly1.push_back(CGAL::Point_2
> <K>
> (2, 1));
>>         poly1.push_back(CGAL::Point_2
> <K>
> (1, 1));
>>         poly1.push_back(CGAL::Point_2
> <K>
> (1, 2));
>>         poly1.push_back(CGAL::Point_2
> <K>
> (0, 2));
>>         CGAL::Polygon_set_2
> <K>
>  poly_set(poly1);
>>
>>         CGAL::Polygon_2
> <K>
>  hole;
>>         hole.push_back(CGAL::Point_2
> <K>
> (0, 0));
>>         hole.push_back(CGAL::Point_2
> <K>
> (1, 0));
>>         hole.push_back(CGAL::Point_2
> <K>
> (1, 1));
>>         hole.push_back(CGAL::Point_2
> <K>
> (0, 1));
>>
>>         poly_set.difference(hole);
>>
>> Note: I have only tested with the EPEC Kernel.
>>
>> The above code results in poly_set containing the following polygon:
>> (0, 1), (1, 1), (1, 0), (2, 0), (2, 1), (1, 1), (1, 2), (0, 2)
>>
>> I would expect it to contain the following polygons:
>> (1, 0), (2, 0), (2, 1), (1, 1)
>>         and
>> (0, 1), (1, 1), (1, 2), (0, 2)
>>
>>
>>
>>
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>>
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>>
>>
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