简述

有时我们需要获取当前TimeLine中Clip的信息(如持续时间)

方法

通过实现ISerializationCallbackReceiver接口来在序列化之前将Clip的信息存入PlayableAsset的实例中

实现

using System;
using System.Linq;
using UnityEditor;
using UnityEngine;
using UnityEngine.Playables;
using UnityEngine.Timeline;

[System.Serializable]
public class Base : PlayableAsset, ISerializationCallbackReceiver
{
	// Clip的信息(开始时间与结束时间)被储存在这里
    [SerializeField][HideInInspector]
    protected double inTime, outTime;
    // PlayableAsset的Clip 减少搜索的次数
    [NonSerialized]
    private TimelineClip clip;

    // Factory method that generates a playable based on this asset
    public override Playable CreatePlayable(PlayableGraph graph, GameObject go)
    {
   		return Playable.Create(graph);
    }

    public void OnAfterDeserialize()
    {
    }

	// 当序列化之前会调用这个函数
	// 主要的部分写在这里
    public void OnBeforeSerialize()
    {
        // 复用Clip减少搜索
        if(clip != null)
        {
            inTime = clip.start;
            outTime = clip.end;
            return;
        }

        // 获取所有TimeLineAsset
        string[] guids = AssetDatabase.FindAssets("t:TimelineAsset");
        var timelines = guids.Select(id => AssetDatabase.LoadAssetAtPath(AssetDatabase.GUIDToAssetPath(id), typeof(TimelineAsset)));
        // 找到包含这个PlayableAsset的Clip
        foreach (TimelineAsset timeline in timelines)
        {
            if (timeline)
            {
                foreach (var track in timeline.GetOutputTracks())
                {
                    foreach (var clip in track.GetClips())
                    {
                        if (clip.asset == this)
                        {
                            inTime = clip.start;
                            outTime = clip.end;
                            this.clip = clip;
                        }
                    }
                }
            }
        }
    }
}