NGUI全屏背景：
LoginPanel_bg = GetCompomentByName(transform, "LoginPanel_bg").GetComponent<UIStretch>();
LoginPanel_bg.initialSize = new Vector2(Screen.width, Screen.height);
LoginPanel_bg.style = UIStretch.Style.FitInternalKeepingRatio;
NGUI 景深效果
右击导入ImageEffects包，然后在Component下的ImageEffects找DepthOfField]