public void drawArrow(boolean ifTower){
        if (ifTower){
            addObject (pa, selectedTower.getX(), selectedTower.getY() - 20);
            pa.setMob (null);
        }
        else{
            Enemy e = ui.getMob();
            if (e.getHp() > 0){
                pa.setMob (e);
                addObject (pa, e.getX(), e.getY() - 20);
            }
        }
    }