// always returns with normalized length
public static Vector2 Slerp(Vector2 fromV, Vector2 toV, float t) {
// oh god this little knot has so many hidden trig and sqrts.
var fromAng = fromV.Angle2D();
var toAng = toV.Angle2D();
float angleDelta = toAng - fromAng;
// make sure we're taking the shortest route
float flipper = angleDelta < 0f ? 360f : -360f;
float maybeFlip = Mathf.Abs(angleDelta) > 180f ? flipper : 0f;
float shortestDelta = angleDelta + maybeFlip;
float angleToMove = shortestDelta * t;
var newDir = fromV.RotateBy2D(angleToMove).normalized;
return newDir;
}
