Traverse the whole polygon in that direction. If you find that you went clockwise, then the interior is to the right; if you went counter-clockwise, it's to the left.
How to determine which side of a polygon edge is inside a polygon, and which is outside?
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19-10-2022 - |
Question
I have an edge of a polygon (convex or concave). I want to find out if, going straight from start to end point of that edge, I have to turn right or left to get inside or outside of polygon. How can I check that?
La solution
Autres conseils
Another approach:
Project a perpendicular line and count how many times it crosses other edges.
odd -> interior
zero or even -> exterior
Equivalently If you happen to have a well optimized point-in-polygon routine available you can project a point some epsilon off the line and throw it into the inside test.
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