public Vector collide(PhysicsObject a){
		if( !open ){
			Vector aPosition = a.getPosition();
			Vector aOldPosition = a.getOldPosition();
			Vector aSize = a.getSize();
			if (a instanceof Player && (aPosition.x + aSize.x > this.currentPosition.x && aPosition.x < this.currentPosition.x + this.size.x) && (aPosition.y + aSize.y > this.currentPosition.y && aPosition.y < this.currentPosition.y + this.size.y)){
				open = true;
				((Player)a).setAmmo(((Player)a).getAmmo()+5);
				return a.getPosition();
			}
			return null;
		} else {
			return null;
		}
	}