Removing antennae from faces in Arrangement_2

[pentacular]

Hello.

I have an arrangement with faces with non-simple boundary polygons.

Looking at the polygon, I see that it is due to an antenna.

6 vertices: (-0.53 -0.47) (-0.401549 -0.476906) (-0.407594 -0.0356515) (0.186278 -0.00770458) (0.213064 -0.50995) (-0.401549 -0.476906)

I couldn't see a best practice for cleaning antennae in cgal at the moment.
Have I missed something, or is this something best handled by application code?

[efifogel]

Hi Brian, First, you need to precisely define what an antenna is. For example, imagine a small polygon strictly inside a large polygon with an edge connecting the two polygons. Is the edge an antenna? If this is not an antenna, then you can simply test whether the face to the left of an edge e is identical to the face on the right (the left to the opposite of e), and if so, remove it. Otherwise, it gets a bit more complicated. You can identify the edges that satisfy the above and the degree of one endpoint is only 1 (only one incoming and one outgoing halfedges). For every such edge continue along the antenna through the other endpoint of the edge. (Make sure that when you remove edges, you don't do it while traversing the arrangement. Instead, collect the candidates in a container, and then traverse and remove the container.) Anyway, there is no built-in function that does it, but it sounds useful to me. Best, Efi ____ _ ____ _ /_____/_) o /__________ __ // (____ ( ( ( (_/ (_/-(-'_(/ _/

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On Wed, 29 Jun 2022 at 18:41, Brian Spilsbury ***@***.***> wrote: Hello. I have an arrangement with faces with non-simple boundary polygons. Looking at the polygon, I see that it is due to an antenna. 6 vertices: (-0.53 -0.47) (-0.401549 -0.476906) (-0.407594 -0.0356515) (0.186278 -0.00770458) (0.213064 -0.50995) (-0.401549 -0.476906) I couldn't see a best practice for cleaning antennae in cgal at the moment. Have I missed something, or is this something best handled by application code? — Reply to this email directly, view it on GitHub <#6726>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABVBNOAHLIB4ZTPAGYYG4ODVRRVEDANCNFSM52GGSK5A> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[pentacular]

Ah, right.

I was focusing on the Polygon_2, but you're right that it's much simpler to handle by checking faces in the Arrangement.

Thanks. :)