Unity开发笔记-Timeline利用Clip实现Rewind回放

效果展示

除了使用signal，timeline也可以通过自定义clip实现rewind回放

原理：

实现PlayableBehaviour的子类，重写ProcessFrame方法，参数中的Playable对象的GetDuration()和GetTime()可以获得当前clip的总时间和当前时间
如果time接近duration，那么设法取到playableDirector，将time减去当前clip已播放的GetTime()即可

下面是PlayableBehaviour核心代码：

public class LoopClipBehavior:PlayableBehaviour
{
    private PlayableDirector director { get; set; }

    public override void ProcessFrame(Playable playable, FrameData info, object playerData)
    {
        double duration = playable.GetDuration();
        double time = playable.GetTime();
        if (Math.Abs(time- duration)<=0.1f) 
        {
            var diff = playable.GetTime();
            director.time -= diff;
        }
        base.ProcessFrame(playable, info, playerData);
    }

    public override void OnPlayableCreate(Playable playable)
    {
        base.OnPlayableCreate(playable);
        director = (playable.GetGraph().GetResolver() as PlayableDirector);
    }
}

同时也需要实现PlayableAsset和TrackAsset的子类

LoopClipTrack.cs

[TrackClipType(typeof(LoopClip))]
public class LoopClipTrack: TrackAsset
{

}

LoopClip.cs

  public class LoopClip : PlayableAsset
  {
    public LoopClipBehavior template = new LoopClipBehavior();
    public override Playable CreatePlayable(PlayableGraph graph, GameObject owner)
    {
        var playable = ScriptPlayable<LoopClipBehavior>.Create(graph, template);
        return playable;
    }
  }