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Point in Polygon Winding Number Inclusion |
 | | The point is outside when this "crossing number" is even; otherwise, when it is odd, the point is inside. |
 | | If this number is even, then the point is outside; otherwise, when the crossing number is odd, the point is inside. |
 | | However, the validity of the crossing number method is based on the "Jordan Curve Theorem" which says that a simple closed curve divides the 2D plane into exactly 2 connected components: a bounded "inside" one and an unbounded "outside" one. |
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