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Note: To open a precomposition, Alt-double-click (Windows) or Option-double-click (Mac OS) it in the Timeline panel.
To open the composition that contains the current precomposition, click the Open Parent Composition button at the top of the Timeline panel.
Precomposing and nesting are very useful for managing and organizing complex compositions.
By precomposing and nesting, you can do the following:
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.
AFTER EFFECTS CS3 114 User Guide 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)).
See also “Create layers from footage items” on page 135 “How render order and collapsed transformations affect 3D layers” on page 175 “Layer switches and columns in the Timeline panel” on page 147 “Work with parent and child layers” on page 158 Precompose layers Precomposing layers places them in a new composition (sometimes called a precomposition), which replaces the layers in the original composition. Precomposing a single layer is useful for adding transform properties to a layer and influencing the order in which elements of a composition are rendered.
1 Select the layers in the Timeline panel, and choose Layer Pre-compose or press Ctrl+Shift+C (Windows) or Command+Shift+C (Mac OS).
2 Select one of the following:
Leave All Attributes In Leaves the properties and keyframes of the precomposed layer in the original composition, applied to the new layer that represents the precomposition. The frame size of the new composition is the same as the size of the selected layer. This option is not available when you select more than one layer, a text layer, or a shape layer.
Move All Attributes Into The New Composition Moves the properties and keyframes of the precomposed layers one level further from the root composition in the composition hierarchy. When you use this option, changes you applied to the properties of the layers remain with the individual layers within the precomposition. The frame size of the new composition is the same as that of the original composition.
Note: Apply your final output settings when you pre-render the nested composition.
1 Select the composition in the Project or Composition panel.
2 Choose Composition Pre-render.
The Pre-render command adds the composition to the render queue and sets the Import & Replace Usage postrender action to replace the composition with the rendered movie.
3 In the Render Queue panel, adjust settings as necessary, and click the Render button to render the composition.
Note: An alternative to replacing the composition with the movie is to use the rendered movie as a proxy for the nested composition.
See also “Use a post-render action” on page 602 “Work with placeholders and proxies” on page 61 “Basics of rendering and exporting” on page 587 Render order and collapsing transformations A composition consists of layers stacked on top of one another in the Timeline panel. When the composition is rendered—either for previewing or for final output—the bottom layer is rendered first. Within each raster (nonvector) layer, elements are applied in the following order: masks, effects, transformations, and layer styles. For continuously rasterized vector layers, transformations occur before masks and effects.
Transformations are changes to those properties grouped under the Transform category in the Timeline panel, including Anchor Point, Position, Scale, Rotation, and Opacity. What you see in the Layer panel is the result of the rendering before transformations are performed.
Note: For additional control over when transformations are performed, you can apply the Transform effect and reorder it with respect to other effects.
In a group of effects or masks, items are processed from top to bottom. For example, if you apply the Circle effect and then apply the Magnify effect, the circle is magnified. However, if you drag the Magnify effect above (before) the Circle effect in the Effect Controls or Timeline panel, the circle is drawn after the magnification and isn’t magnified.
After a layer has been rendered, rendering begins for the next layer. The rendered layer below may be used as input to the rendering of the layer above—for example, for determining the result of a blending mode.
If a composition contains other compositions nested within it, the nested composition is rendered before other layers.
If the Collapse Transformations switch is selected for a nested composition, then the transformations for the nested composition are not performed until after the masks and effects for the containing composition are rendered.
This allows the transformations for the nested composition and the containing composition to be combined—or collapsed—and performed together. The same is true for vector layers that are not continuously rasterized.
Note: Instead of a Collapse Transformations switch, vector layers have a Continuously Rasterize switch in the same location. Vector layers include shape layers, text layers, and layers with vector graphic files as the source footage. Text layers and shape layers are always continuously rasterized.
AFTER EFFECTS CS3 116 User Guide Collapsing transformations can, for example, preserve resolution when a layer is scaled down by half in a nested composition, and the nested composition is scaled up by a factor of two in the containing composition. In this case, rather than performing both transformations and losing image data in the process, one transformation can be performed—doing nothing, because the individual transformations cancel each other.
If transformations are not collapsed, a nested composition that contains 3D layers is rendered as a 2D image of the 3D arrangement, using the default composition camera. This prevents the nested composition from intersecting with 3D layers, casting shadows on 3D layers, and receiving shadows from 3D layers in the containing composition.
The nested composition is also not controlled by the containing composition’s cameras and lights.
If transformations are collapsed, the 3D properties of the layers in the nested composition are exposed to the containing composition. Thus, the nested composition can intersect with 3D layers, cast shadows on 3D layers, and receive shadows from 3D layers in the containing composition. The containing composition's camera and lights can also control the nested composition.
When a closed mask (with mask mode other than None), a layer style, or an effect is applied to a nested composition with collapsed transformations, the layers in the nested composition are first rendered on their own, then masks and effects are applied, and then the result is composited into the main composition. This rendering order means that the blending modes of the nested layers are not applied to any underlying layers in the main composition, and that 3D layers above and below the collapsed layer cannot intersect or cast shadows on each other.
See also “How render order and collapsed transformations affect 3D layers” on page 175 “Change the stacking order for selected layers” on page 138 “Transform effect” on page 417
If you add one composition to another, the original composition becomes a layer in the composition. All of the nested composition’s composition-time markers become layer-time markers in the timeline of the parent composition. These markers are not linked to the original composition-time markers. Changes you make to the composition-time markers in the original composition do not affect layer-time markers in the nested composition. For example, if you remove one of the original composition-time markers, the corresponding layer-time marker for the nested composition remains in place.
See also“Reviewing movies with Clip Notes comments” on page 634
Work with composition-time markers Composition-time markers appear on the time ruler in the Timeline panel. If you remove a marker, the other markers remain numbered as they were. If you change the comment from the default number, that number may be reused by a composition-time marker created later.
Note: Numbering of composition-time markers begins at 0. In After Effects 7.0 and earlier, numbering started at 1.
When you render a composition for comments using Adobe Clip Notes, the comments in composition-time markers are included as comments in the Clip Notes PDF. When you import the comments from a Clip Notes review back into After Effects, the reviewers’ PDF comments are converted back to composition-time markers.
• To add a composition-time marker from the bin, drag the marker from the Comp Marker Bin button.
Dragging a composition-time marker from the Comp marker bin.
• To add a composition-time marker at the current time, press Shift + a number key (0 to 9) on the main keyboard.
Note: If the number you press is already used by another composition-time marker, After Effects does not create a new marker. Instead, it moves the existing marker with that number to the new position.
• To move a composition-time marker, drag it to a different time or double-click it and enter a time in the dialog box.
• To edit a marker’s data, double-click the marker.
• To remove a composition-time marker, drag the marker to the Comp Marker Bin button or Ctrl-click (Windows) or Command-click (Mac OS) the marker.
Work with layer-time markers Layer-time markers are retained when you render to AVI or QuickTime format.
Layer-time markers appear as small triangles on a layer-duration bar. You can have any number of layer-time markers in a layer. You can also drag existing markers to new time locations or remove them, as needed. You can double-click the layer-time marker at any time to view or modify its attributes.
• To add a layer-time marker to selected layers at the current time, choose Layer Add Marker or press * (multiply) on the numeric keypad.
• To move a layer-time marker, drag it to a different time or double-click it and enter a time in the dialog box.
• To edit a marker’s data, double-click the marker.
• To remove a layer-time marker, Ctrl-click (Windows) or Command-click (Mac OS) the marker.
• To remove all layer-time markers from selected layers, right-click (Windows) or Control-click (Mac OS) a marker, and choose Delete All Markers.
• To lock layer-time markers, right-click (Windows) or Control-click (Mac OS) a marker, and choose Lock Markers.
Paul Tuersley provides a script for splitting layers at layer-time markers:
Create a web link, chapter link, or cue point from a marker You can associate a Uniform Resource Locator (URL) with a marker to create an automatic link to that site. After Effects embeds this information within certain kinds of movies, including Flash (SWF), Windows Media, and QuickTime movies. When these movies are played in a web browser, the embedded URL is recognized, initiating a jump to the specified URL. You can target a specific frame in the site.