CGAL users discussion list

[Sebastien Loriot <>]

I think in the arrangement book:
http://acg.cs.tau.ac.il/cgal-arrangement-book

there is some code to fix self-intersecting polygons using winding numbers.

The code of the example is also available at the URL above.

Best,

Sebastien.

On 1/21/21 6:10 PM, Dov Grobgeld ( via 
cgal-discuss Mailing List) wrote:
> Hi all,
>
> In my efforts to deal with a large variety of fonts in my text to glyph 
> generator, https://github.com/dov/pomelo 
> <https://github.com/dov/pomelo>, have I encountered several cases of 
> "bad" contours that I need to clean. One of the problems can be seen in 
> the following figure:
>
> foo.png
> The input is the purple polyline on the left. My desired output are the 
> blue and the green polylines on the right, while dropping the red 
> polyline. My idea of how to do this was to use arrangements.After doing 
> an arrangement, so I thought, the generated separated polylines, would 
> keep the segment orientations of the input. Since I know the desired 
> direction of the polyline, (I know whether I'm looking for an outer 
> boundary or on a hole), I can drop polylines whose orientations are not 
> as expected.
>
> Unfortunately this doesn't work. I found that boundaries of the faces 
> that Arrangement_2 generate are all the in the same direction.
>
> Am I missing something?  How can I prune the red polyline?
>
> Here are the input coordinates of the input as a svg d path:
>
> m 457.2054,532.00482 -2.16634,-106.13373 2.48438,-79.73047 
> 4.94872,-58.86624 15.90675,0.0928 -9.17579,50.94531 -7.96093,57.34766 
> -3.03516,15.03515 -5.07812,10.16406 -7.16537,4.46318 -9.10807,1.23214 
> 8.85783,1.10863 7.45076,4.90699 5.07032,10.11328 3.01562,14.85157 
> 8.83504,74.12725 z
>
> Thanks!
>
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