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I would like to know how to know the "edge immediately to the left of a vertex", just by using geometry?

Here is an image showing the problem.

For instance, how can I know that edge e5 is directly left to vertex e4. Or that the edge directly left to vertex v14 is e9.

TylerH
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Priastou
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  • How this polyline is described? How much vertices may polyline consist of? Give us more information. – MBo May 24 '14 at 13:22
  • The polygon show be a simple polygon. I just want to know the edge directly left to a vertex in a simple polygon. From the image, we know 'visually' that the edge e5 is directly left to the vertex v4. 'Geometrically', how to do that? Should I use ray from vertex v4 or something else? Thanks – Priastou May 24 '14 at 14:25
  • I'm voting to close this question as off-topic because it's not about programming but about math. – TylerH Dec 13 '19 at 15:34

1 Answers1

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You may keep edges in segment tree structure - sorted by Y-coordinate. So it is possible to find edges (fast) that left-ray from vertice will intersect, and choose the closest intersection point.

MBo
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