// Convenience function to add a collider to a given node
public static T AddCollider <T>(Node node, float fric = 1, float dens = 1, float elas = 0) where T : CollisionShape2D
{
CollisionShape2D s = node.CreateComponent <T>();
s.SetFriction(fric);
s.SetDensity(dens);
s.SetRestitution(elas);
return((T)s);
}