import "luxe: math" for Math

class Util{
	//cirle circle intersections, largely taken from http://paulbourke.net/geometry/circlesphere/
	static circle_intersect_circle(o1, r1, o2, r2){
		var diff_x = o2.x - o1.x
		var diff_y = o2.y - o1.y

		var distance = Math.length(diff_x, diff_y)
		if(distance > r1 + r2) return //too far away
		if(distance < (r1 - r2).abs) return //contain each other
		if(distance <= Num.smallest) return //infinite solutions
		
		var a = (r1*r1 - r2*r2 + distance*distance) / (2 * distance) //adjacient length of triangle between o1, midpoint and intersection
		var h = (r1*r1 - a*a).sqrt //hypotenuse length of triangle between o1, midpoint and intersection

		var mid_x = o1.x + a * (o2.x - o1.x) / distance
		var mid_y = o1.y + a * (o2.y - o1.y) / distance

		var inter1 = [
			mid_x + h * diff_y / distance,
			mid_y - h * diff_x / distance
		]

		var inter2 = [
			mid_x - h * diff_y / distance,
			mid_y + h * diff_x / distance
		]

		return [inter1, inter2]
	}
}