Intersection makes no sense to me. about greinerhormann HOT 3 CLOSED

Ah, nevermind, I see it. The points [2,1] and [2,1] repeated... The second one should be 1,2.

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The shapes you've provided make little sense, too. They have collapsed edges. What is the source of those?

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So the issue is that I don't understand the required format for polygons. And have no clue what collapsed edges are or how to avoid them. I was just assuming you provide a set of 2d points, in this case, they describe the corner of a rectangle and the other is a rectangle with one point moved out of place. So e.g. [[1,1],[2,1],[2,2],[2,1],[1,1]] is "start at x=1, y=1. Move to x=2, y=1" and so on through x2y2, x2y1, and finally return to x1y1.

Can you point me at how polygons should be defined?

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