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);

Call this with any time in the track’s range, in any order. Forward, backward, the exact same instant twice, it always works.

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.

Six circles fly in staggered, growing and recoloring together, then a bounce ripples through the row once they’ve landed, flashing back toward cyan as each one grows. All of it, forward or backward, is the same baked Track, sampled at whatever time you ask for. Drag the scrubber, jump around, run it backward: nothing gets re-simulated.

Next

Building a Backend covers what registry and world actually are.