Unity TimeLine自定义轨道（实践）

public class SingingBehaviour : PlayableBehaviour
{
    public string text;
    public override void ProcessFrame(Playable playable, FrameData info, object playerData)
    {
        var textControl = playerData as TextControl;
        var progress = playable.GetTime() / playable.GetDuration();
        textControl.UpdateText(text,(float)progress);
    }
}

public class SingingClip : PlayableAsset, ITimelineClipAsset
{
    private readonly SingingBehaviour _singingBehaviour = new SingingBehaviour();
    public string text;

    public override Playable CreatePlayable(PlayableGraph graph, GameObject owner)
    {
        var playable = ScriptPlayable.Create(graph, _singingBehaviour);
        var clone = playable.GetBehaviour();
        clone.text = text;
        return playable;
    }

    public ClipCaps clipCaps => ClipCaps.None;
}

[TrackColor(0.5f,0.4f,0.4f)]
[TrackClipType(typeof(SingingClip))]
[TrackBindingType(typeof(TextControl))]
public class SingingTrack : PlayableTrack
{
    public override Playable CreateTrackMixer(PlayableGraph graph, GameObject go, int inputCount)
    {
        return ScriptPlayable.Create(graph, inputCount);
    }
}

public class SingingMixerBehaviour : PlayableBehaviour
{
    public override void ProcessFrame(Playable playable, FrameData info, object playerData)
    {
        var textControl = playerData as TextControl;
        var count = playable.GetInputCount();
        var isEmpty = true;
        for (var i = 0; i < count; i++)
        {
            var inputWeight = playable.GetInputWeight(i);
            if (inputWeight > 0f)
            {
                isEmpty = false;
            }
        }

        if (isEmpty)
        {
            textControl.UpdateText("",0f);
        }
    }
}

public class TextControl : MonoBehaviour
{
    [SerializeField] private TextMeshProUGUI backTextMeshPro;
    [SerializeField] private TextMeshProUGUI forwardTextMeshPro;
    [SerializeField] private RectMask2D rectMask2D;


    public void UpdateText(string text, float progress)
    {
        backTextMeshPro.text = text;
        forwardTextMeshPro.text = text;
        var x = forwardTextMeshPro.preferredWidth * progress;
        rectMask2D.rectTransform.sizeDelta = new Vector2(x, forwardTextMeshPro.rectTransform.sizeDelta.y);
    }
}