/// <summary>
/// 渐变
/// </summary>
/// <param name="graphic"></param>
/// <param name="duration"></param>
/// <param name="to"></param>
/// <returns></returns>
public static ActionInterval CCFadeTo(this Graphic graphic, float duration, float to = 1)
{
to = Mathf.Clamp01(to);
return(graphic.CCColorTo(duration, new Color(graphic.color.r, graphic.color.g, graphic.color.b, to)));
}