public static final double DEFAULT_X_OFFSET = 12.0;

    /** The default y-offset for the 3D effect. */
    public static final double DEFAULT_Y_OFFSET = 8.0;

    /** The default wall paint. */
    public static final Paint DEFAULT_WALL_PAINT = new Color(0xDD, 0xDD, 0xDD);

    /** The size of x-offset for the 3D effect. */
    private double xOffset;

    /** The size of y-offset for the 3D effect. */
    private double yOffset;

    /** The paint used to shade the left and lower 3D wall. */
    private transient Paint wallPaint;