Question Trying to get a track to pass a class reference to a playable behavior

Let's say we have the following components:

Code (CSharp):

1. public class BaseComponent : MonoBehaviour { }
2. public class DerivedComponent : BaseComponent { }

I can define a new track like this:

Code (CSharp):

1. [TrackBindingType(typeof(BaseComponent))]
2. public class TrackBindingExample : TrackAsset { }

The Timeline window will only allow gameobjects with a component that is a BaseComponent (or a derived type) as a binding for your track.



In ProcessFrame, the playerData object will be the component assigned to the track:

Code (CSharp):

1. public class ClipExample : PlayableAsset
2. {
3.     public override Playable CreatePlayable(PlayableGraph graph, GameObject owner)
4.     {
5.         return ScriptPlayable<PlayableExample>.Create(graph);
6.     }
7. }
8.  
9. class PlayableExample : PlayableBehaviour
10. {
11.     public override void ProcessFrame(Playable playable, FrameData info, object playerData)
12.     {
13.         Type dataType = playerData.GetType();
14.         Debug.Log($"PlayerData type: {dataType}");
15.     }
16. }

After adding the clip to the timeline, the console will print: PlayerData type: DerivedComponent

If you have a base interface instead of a class, Timeline won't automatically assign the binding; you'll have to add additional code to select the correct component. The TrackEditor class has methods to control which object can be bound to a track: IsBindingAssignableFrom and GetBindingFrom.