[游戏开发]关于unity协程等待方法WaitForSecondsRealtime的发现

public class WaitForSecondsRealtime : CustomYieldInstruction
    {
        private float m_WaitUntilTime = -1f;

        /// <summary>
        ///   <para>The given amount of seconds that the yield instruction will wait for.</para>
        /// </summary>
        public float waitTime
        {
            get;
            set;
        }

        public override bool keepWaiting
        {
            get
            {
                bool flag = this.m_WaitUntilTime < 0f;
                if (flag)
                {
                    this.m_WaitUntilTime = Time.realtimeSinceStartup + this.waitTime;
                }
                bool flag2 = Time.realtimeSinceStartup < this.m_WaitUntilTime;
                bool flag3 = !flag2;
                if (flag3)
                {
                    this.m_WaitUntilTime = -1f;
                }
                return flag2;
            }
        }
        /// <summary>
        ///   <para>Creates a yield instruction to wait for a given number of seconds using unscaled time.</para>
        /// </summary>
        /// <param name="time"></param>
        public WaitForSecondsRealtime(float time)
        {
            this.waitTime = time;
        }
    }

从源码里可以看出，在等待时间到达的那一帧，flag2为fales，所以m_WaitUntilTime 被置为了-1，当同一帧再次获取keepWaiting值时，flag2就重新报变为true了。因为update在协程前调用，所以当update里每帧都获取keepWaiting时，协程就无法进行下去。