Thanks! One more thing. I don't get "getObjectsAtOffset", what i know it is almost same as getIntersectingObjects? Do x and y mean how far from the object it will intersecting?

With 'getObjectsAtOffset(x, y, class)', which is an Actor class method (executed on an Actor object; henceforth called 'this'), if the image of an object of type 'class' overlaps the point (this.getX()+x, this.getY()+y) then the boolean return would be 'true'.