> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lightcraft.pro/llms.txt
> Use this file to discover all available pages before exploring further.

# Timeline

> Control playback, manage animation clips, and work with audio tracks in the scene editor

## Interface overview

The timeline sits below the 3D canvas and includes:

* **Playhead** — Shows the current time position. Drag it to scrub through the scene.
* **Ruler** — Displays time markers for reference.
* **Tracks** — Rows for animation clips, audio files, and camera ranges, grouped under the active setup.

## Playback

Use the play, pause, and scrub controls to preview your scene. Playback runs all active animation clips and audio tracks simultaneously.

### Keyboard shortcuts

| Shortcut                               | Action                                                       |
| -------------------------------------- | ------------------------------------------------------------ |
| **Spacebar**                           | Play and pause.                                              |
| **Shift+Up**                           | Jump the playhead to the start of the timeline.              |
| **Left / Right arrows**                | Step the playhead backward and forward.                      |
| **Ctrl+scroll** (hover over timeline)  | Zoom in or out on the time span.                             |
| **Shift+scroll** (hover over timeline) | Pan left or right when only part of the timeline is visible. |

## Animation clips

Animation clips contain keyframed movement for objects and cameras. Each clip appears as a bar on the timeline that you can move, trim, or extend.

### Pre-animated USD assets

If you import a USD asset that already contains animation (a rigged character, for example):

1. Open the **Outliner** panel.
2. Expand the active setup, then its **Objects** folder, then the asset.
3. Expand its **Animation** node.
4. Hover the row and click **+** ("Add to timeline at playhead") to add the clip at the current playhead position, at normal speed.
5. Toggle **Keyframes** on for that object.

<Warning>
  Without Keyframes enabled, pre-animated USD assets may render correctly in the browser but sit frozen on playback in the Spark iOS app.
</Warning>

<Tip>
  Adding a clip this way is undoable with **Cmd+Z**, like any other timeline edit.
</Tip>

## Audio tracks

Add audio files to the timeline for reference during camera planning. Audio tracks display waveforms so you can visually sync camera movement or scene events to sound cues. Unlike objects and cameras, audio tracks are not scoped to a setup.

## Camera ranges

Camera ranges appear on the timeline as highlighted sections, each corresponding to a camera in the active setup. Adjusting a camera range changes that camera's start and end time. Only the active setup's cameras and objects are shown; switch setups to see a different set of ranges.