How can I add curve keys and recording to a custom track?

You shouldn't need to use the API to use animated parameters on tracks and clips. It is completely dependent on how the custom tracks and clips are structured.

However, animated parameters on clips and tracks are animating values on the Track/PlayableAsset, not on the target component like AnimationTracks do.

Here's an example:

Code (CSharp):

1.     [Serializable]
2.     public class TextPlayableBehaviour : PlayableBehaviour
3.     {
4.         public Color color = Color.white; // automatically animated
5.         public int fontSize = 14;        
6.         public string text = "";
7.  
8.         // ProcessFrame would copy these value to the Text object bound to the track...
9.     }
10.  
11.  
12.     // Represents the serialized data for a clip on the TextTrack
13.     [Serializable]
14.     public class TextPlayableAsset : PlayableAsset
15.     {
16.         public TextPlayableBehaviour template = new TextPlayableBehaviour();
17.  
18.         public override Playable CreatePlayable(PlayableGraph graph, GameObject owner)
19.         {
20.             // Using a template will clone the serialized values
21.             return ScriptPlayable<TextPlayableBehaviour>.Create(graph, template);
22.         }
23.     }
24.  
25.  

This works for either a track or a clip. Timeline will automatically detect that a template is being used inside the playable asset, and manage curves on the playable behaviour in the inline curve editor. The button to expand the curve editor is on the track header, like the animation track.

The curve editor will show only animatable properties. If it's not currently animated, a constant curve is shown. Keys can be added (recorded) using the context menu in the inspector, or by editing the curve directly.

When you modify the curves in editor, those parameters are automatically updated before PrepareFrame or ProcessFrame calls are run on your PlayableBehaviour.

v1.4.5 fixes a bunch of bugs with these types of curves in the editor, so I'd recommend using that version if possible.

If you are copying the behaviour values to a Component, then you need to specify which Component values you are modifying in GatherProperties so when previewing is disabled, their scene values are properly restored. But you do not need to specify anything for PlayableBehaviour values.

If you want to set values in the API, then CreateCurves can be used to initialize the animation clip for the animated properties.

After creating the curve, values can be set via API using animation apis:
e.g.
AnimationUtility.SetEditorCurve(clip.curves, typeof(TextPlayableAsset), "color.r", AnimationCurve.Linear(0,0,1,1));

Note - the type is the type of PlayableAsset (or track asset), but the "template". prefix for the color parameter isn't required.

I hope that helps.

 

The answers to your four questions:

• No, You don't need to name it "template".
  
• Yes*
  
• No, but only fields that exist on the type returned by CreatePlayable will be animated.
  
• I'll have to check.

* Only fields serialized on a PlayableAsset as part of a PlayableBehaviour can be animated.

You can put as many PlayableBehaviours as you want in your PlayableAsset, but only the fields that exist on the PlayableBehaviour that you pass to

ScriptPlayable<PlayableBehaviourT>.Create(graph, template);

will be animated at Runtime.

You don't need to pass in the template to

ScriptPlayable.Create

, although you should, but you will need to serialize the type of PlayableBehaviour that you instantiate in

CreatePlayable

in your PlayableAsset in order to get access to this animation feature.