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Subject: [geometry] Correcting an invalid polygon.
From: Adam Starkey (adam_at_[hidden])
Date: 2012-11-28 11:27:24

Apologies if this has been covered elsewhere. It seems like it should have
been, but my Google foo is only returning old, out of date pages.

I need to remove degeneracies from polygons that have been manually drawn by
users. The polygons are being draw either by free=hand mouse dragging or
with a stylus, and will typically have closely packed vertices, which makes
it hard to block the introduction of self-intersections or self-tangents
whilst capturing the contour.

As far as i can see all of the main set operators require both two inputs
and that the inputs already be valid. What is the preferred way of making a
polygon valid?

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