About nesting and precomposing
Nesting is the inclusion of one composition within another. The nested composition appears as a layer in the containing composition.
If you want to group some layers that are already in a composition, you can precompose those layers. Precomposed layers are placed in a new composition (sometimes called a precomposition), and the new composition becomes the source for a single layer in the original composition. The new composition appears in the Project panel and is available for rendering or use in any other composition.
You can also nest compositions by adding an existing composition to another composition, just as you would add a footage item to a composition.
button
at the top of the Timeline panel.Precomposing and nesting are very useful for managing and organizing complex compositions.
- Apply complex changes to an entire composition
- You can create a composition that contains multiple layers, nest the composition within the overall composition, and animate and apply effects to the nested composition so that all of the layers change in the same ways over the same time period.
- Reuse anything you build
- You can build an animation in its own composition and then drag that composition into other compositions as many times as you want.
- Update in one step
- When you make changes to a nested composition, those changes affect every composition in which it is used, just like changes made to a source footage item affect every composition in which it is used.
- Alter the default rendering order of a layer
- You can specify that After Effects render a transformation (such as rotation) before rendering effects, so that the effect applies to the rotated footage.
- Add another set of transform properties to a layer
- The layer that represents the composition has its own properties, in addition to the properties of the layers that it contains. This allows you to apply an additional set of transformations to a layer or set of layers.
For example, you can use nesting to make a planet both rotate and revolve (moving like the Earth, which spins on its own axis and also travels around the Sun). To do this, you animate the Rotation property of the planet layer, precompose that layer, modify the Anchor Point property of the precomposition layer, and then animate the Rotation property of the precomposition layer.
Because a precomposition is itself a layer, you can control its behavior using layer switches and composition switches in the Timeline panel. You can choose whether changes made to the switches in the containing composition are propagated to the nested composition. To prevent layer switches from affecting nested compositions, choose Edit > Preferences > General (Windows) or After Effects > Preferences > General (Mac OS), and then deselect Switches Affect Nested Comps.
In the Advanced composition settings (Composition > Composition Settings), choose Preserve Resolution When Nested or Preserve Frame Rate When Nested Or In Render Queue for a composition to retain its own resolution or frame rate, and not inherit those settings from the containing composition. For example, if you deliberately used a low frame rate in a composition to create a jerky, hand-animated result, you should preserve the frame rate for that composition when it is nested. Similarly, the results of rotoscoping may look wrong when converted to a different frame rate or resolution. Use this setting instead of the Posterize Time effect, which is less efficient.
Changing the current time in one panel updates the current time in other panels associated with that composition. By default, the current time is also updated for all compositions related to the current composition by nesting. To prevent compositions related by nesting from updating their current times when you change the current time in one composition, deselect the Synchronize Time Of All Related Items preference (Edit > Preferences > General (Windows) or After Effects > Preferences > General (Mac OS)).
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