Getting the Clip Start End Times through to the mixer

ClipStartEndInMixer.cs

/* 1 - Overriding CreateTrackMixer in the CustomTransformationTrack class,
       getting the start & end times for each clip, and passing them to the custom clip class. */

//[Omitted...]
public class CustomTransformationTrack : TrackAsset
{
	public override Playable CreateTrackMixer(PlayableGraph graph, GameObject go, int inputCount)
	{
		foreach (var clip in GetClips())
		{
			var customClip = clip.asset as CustomTransformationClip;
			if (customClip != null)
			{
				customClip.CustomClipStart = clip.start;
				customClip.CustomClipEnd = clip.end;
			}
		}
		return ScriptPlayable<CustomTransformationMixerBehaviour>.Create (graph, inputCount);
	}
	//[Omitted...]
}


/* 2 - Overriding CreatePlayable in the CustomTransformationClip class, 
       passing those same start & end times of that specific clip on to the custom behaviour class. */
       
//[Omitted...]
public class CustomTransformationClip : PlayableAsset, ITimelineClipAsset
{
    //[Omitted...]
    
    public double CustomClipStart { get; set; }
    public double CustomClipEnd { get; set; }

    public override Playable CreatePlayable (PlayableGraph graph, GameObject owner)
    {
        var playable = ScriptPlayable<CustomTransformationBehaviour>.Create (graph, template);
        playable.GetBehaviour().CustomClipStart = CustomClipStart;
        playable.GetBehaviour().CustomClipEnd = CustomClipEnd;
        return playable;
    }
}

/* 3 - Accessing these values in the mixer, when applying the transformations.
   Got the timeline 'playhead time' from https://forum.unity.com/threads/how-to-get-playable-gettime-when-not-in-play-mode.496047/ */

//[Omitted...]
public class CustomTransformationMixerBehaviour : PlayableBehaviour
{
	private bool _firstFrameHappened;
	private Quaternion _defaultRotation;
	private Transform _trackBinding;

	//[Omitted...]
	public override void ProcessFrame(Playable playable, FrameData info, object playerData)
    	{
        	_trackBinding = playerData as Transform;

		if (!_trackBinding)
			{ return; }

		int inputCount = playable.GetInputCount();
		if (inputCount == 0)
			{ return; }

		//Picked up this trick from the LightControlMixerBehaviour in the DefaultPlayables examples.
		if (!_firstFrameHappened)
		{
			_defaultRotation = _trackBinding.rotation;
			_firstFrameHappened = true;
		}

		double playTime = playable.GetGraph().GetRootPlayable(0).GetTime();
		Quaternion rotation = Quaternion.identity;

		for (int i = 0; i < inputCount; i++)
		{
			var inputPlayable = (ScriptPlayable<CustomTransformationBehaviour>)playable.GetInput(i);
			CustomTransformationBehaviour input = inputPlayable.GetBehaviour();

			double customDuration = input.CustomClipEnd - input.CustomClipStart;
			float normalizedClipPosition = Mathf.Clamp01((float)((playTime - input.CustomClipStart) / customDuration));
			float rotationToAdd = input.GetAngle(normalizedClipPosition);
			rotation *= Quaternion.Euler(Vector3.right * rotationToAdd);
		}

		_trackBinding.rotation = _defaultRotation * rotation;
	}
	
	public override void OnGraphStop(Playable playable)
	{
		if (_trackBinding != null)
			{ _trackBinding.rotation = _defaultRotation; }

		base.OnGraphStop(playable);
	}
}