How to know if a polygon is simple

[opyate]

Hello, GoostGeometry2D.polygon_centroid says

For accurate results, the polygon must be strictly simple, meaning there should be no self-intersecting edges.

I looked through the doc and couldn't find a function for determining if a polygon is strictly simple. Could this be a useful feature to add to Goost?

I'm currently using this, but also not sure if it's entirely bug-free:

func polygon_is_simple(polgon: PoolVector2Array) -> bool:
	"""Checks if a polygon is simple.
	
	I.e. it doesn't self-intersect, or none of the edges are flush.
	
	From https://github.com/godotengine/godot-proposals/issues/1389#issuecomment-676635466
	"""
	var s = polgon.size() - 1
	for i in range(0,s):
		var p1: Vector2 = polgon[i]
		var p2: Vector2 = polgon[i+1 % s]
		for j in range(0,s):
			var p1a: Vector2 = polgon[j]
			var p2a: Vector2 = polgon[j+1 % s]
			var intersect = Geometry.segment_intersects_segment_2d(p1,p2,p1a,p2a)
			if intersect != null: 
				return false
	return true

[opyate]

PS just saw the notes around strict simplicity on PolyBoolean2D doc, so perhaps this extra func I'm asking about is not needed.

[Xrayez]

I looked through the doc and couldn't find a function for determining if a polygon is strictly simple. Could this be a useful feature to add to Goost?

Yes because this kind of method was also proposed at Godot's proposals as well. I see you linked godotengine/godot-proposals#1389!

Performance-wise it may be faster to do merge operation on input polygons (even when no set of polygons need to be actually merged).

Nonetheless, implementing is_polygon_simple() method would be alright, but I haven't needed such a method myself to be honest (perhaps it may be useful for procedural generation purposes as well, I presume).

[opyate]

Thanks for the reply! I'll go with the merge operation.