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Asked By
SteveSmith
I’m running the following code:
var polygon : PoolVector2Array
polygon.append(Vector2(0, 20))
polygon.append(Vector2(100, 20))
polygon.append(Vector2(100, 0))
polygon.append(Vector2(0, 0))
# Returns false:-
var result = Geometry.is_point_in_polygon(Vector2(0,1), polygon)
As far as I can see, “result” should be true since 0, 1 is inside this polygon (which is just a rectangle) but it returns false. Is Geometry.is_point_in_polygon() broken?
I was going to suggest that False seems reasonable since your specified point actually lines ON (rather than IN) the polygon’s boundary. But, checking the docs, I see this:
Returns true if point is inside polygon or if it’s located exactly on polygon’s boundary, otherwise returns false.
So, as documented, I would expect your test to return True.
A test of a point at 1, 1 does return True, as expected (as does 0.001, 1). So, at least on the surface, the results of your test do indeed seem wrong.
Interestingly I think it might be the zero causing the issue here. If I use the below I get true as expected as the outcome.
var polygon : PoolVector2Array
polygon.append(Vector2(1, 20))
polygon.append(Vector2(100, 20))
polygon.append(Vector2(100, 1))
polygon.append(Vector2(1, 1))
# Returns true:-
var result = Geometry.is_point_in_polygon(Vector2(100,1), polygon)
Gluon | 2022-12-02 22:19
I’ve discovered that if I invert() the polygon, it does work. Maybe the function only works with anti-clockwise polygon data?
