CrossingCount

CrossingCount[contour, p] gives a count of the number of times a ray starting from the point p crosses the closed curve contour.

Examples

Count ray crossings for a polygon:

polygon = Polygon[{{0, 0}, {1, 0}, {1, 1}, {0, 1}}];
CrossingCount[polygon, {0.5, 0.5}]
(* 1 - point is inside *)

Point outside:

CrossingCount[polygon, {2, 2}]
(* 0 - point is outside *)

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