Timeline

Once your fragments are ordered the way you want, .compile() freezes the result into a Track.

let track = fragment.compile();

Building the timeline

The builder turns one or more tracks into a Timeline.

let mut timeline = b.compile(track);

Baking

Before it can be sampled, a timeline is baked once. This runs every action’s closure exactly one time and records its start and end values.

timeline.bake_actions(&registry, &world);

Sampling

Move the playhead, then write the values back into your world.

timeline.set_target_time(cs(50));
timeline.queue_actions();
timeline.sample_queued_actions(&registry, &mut world);

You can call this with any time in the track’s range, in any order: forward, backward, or the same instant twice.

Two-way playback

Sampling only ever reads two already-baked values and interpolates between them. Nothing gets replayed, so moving backward costs exactly the same as moving forward.

In the demo below, six circles fly in on a stagger, growing and changing color, then a bounce ripples through the row. All of it is one baked Track, sampled at whatever time the scrubber asks for.