comp

Comp

thisComp

comp("CompName")

layer("layerName").source

These attributes and methods can be called on Comp objects.

These are typically accessed in a few ways, most commonly:

• thisComp to get the Comp object of the active comp the expression is written in,
• comp("CompName") to get a specific comp by name,
• layer("layerName").source, if referring to a precomp layer, to get the targeted precomp layer’s source comp

On this page, we’re going to use thisComp as a sample on how to call these items, however note that any method that returns a Comp will work.

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Attributes

Comp.activeCamera

thisComp.activeCamera

Description

Returns the Camera object for the camera through which the composition is rendered at the current frame.

This camera is not necessarily the camera through which you are looking in the Composition panel.

Type

Camera

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Comp.bgColor

thisComp.bgColor

Description

Returns the background color of the composition.

Type

Array (4-dimensional)

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Comp.displayStartTime

thisComp.displayStartTime

Description

Returns the composition start time, in seconds.

Type

Number

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Comp.duration

thisComp.duration

Description

Returns the composition duration, in seconds.

Type

Number

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Comp.frameDuration

thisComp.frameDuration

Description

Returns the duration of a frame, in seconds.

Type

Number

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Comp.height

thisComp.height

Description

Returns the composition height, in pixels.

Type

Number

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Comp.marker

thisComp.marker

Description

Returns a given composition’s Marker property.

Note

If you have a project created in a previous version of After Effects that uses composition marker numbers in expressions, you must change those calls to use marker.key(name) instead. Because the default name of a composition marker is a number, converting the reference to use the name is often just a matter of surrounding the number with quotation marks.

Type

Marker Property

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Comp.name

thisComp.name

Description

Returns the name of the composition.

Type

String

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Comp.ntscDropFrame

thisComp.ntscDropFrame

Note

This functionality was added in After Effects CS5.5

Description

Returns true if the timecode is in drop-frame format.

Type

Boolean

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Comp.numLayers

thisComp.numLayers

Description

Returns the number of layers in the composition.

Type

Number

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Comp.pixelAspect

thisComp.pixelAspect

Description

Returns the pixel aspect ratio of the composition.

Type

Number

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Comp.shutterAngle

thisComp.shutterAngle

Description

Returns the shutter-angle value of the composition, in degrees.

Type

Number

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Comp.shutterPhase

thisComp.shutterPhase

Description

Returns the shutter phase of the composition, in degrees.

Type

Number

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Comp.width

thisComp.width

Description

Returns the composition width, in pixels.

Type

Number

Example

Apply the following expression to the Position property of a layer to center the layer in the composition frame:

[thisComp.width / 2, thisComp.height / 2];

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Methods

Comp.layer()

thisComp.layer(index)

thisComp.layer(name)

thisComp.layer(otherLayer, relIndex)

Description

Return the Layer object with the specified index or name.

The index value refers to the layer order in the Timeline panel.

The name value refers to the user-specified layer name, or the layer source name if there is no layer name.

If duplicate names exist, After Effects uses the first (topmost) one in the Timeline panel.

If using the otherLayer, relIndex call, this retrieves the layer that is relIndex layers above or below otherLayer.

Parameters

Parameter	Type	Description
index	Number	Layer name or index to get.
name	String
otherLayer	Layer	The “other” layer to start getting layers relative to
relIndex	Number	The number of layers to move above or below the otherLayer

Returns

Layer, Light, or Camera object

Example

Get the 3rd layer in the current comp:

thisComp.layer(3)

Get the layer named “Solid 1” from the current comp:

thisComp.layer("Solid 1")

Check whether the next layer down in the Timeline panel is active:

const nextLayer = thisComp.layer(thisLayer, 1);
nextLayer.active;

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Comp.layerByComment()

thisComp.layerByComment(comment)

Description

Retrieves a layer by matching the comment parameter to the value in the layer’s Comment column.

The matches are simple text matches. They will match partial words, and are case sensitive. Matching does not appear to use regular expressions or wildcards. If duplicate comments exist, After Effects uses the first (topmost) one in the Timeline panel.

Parameters

Parameter	Type	Description
comment	String	The comment to find a layer from

Returns

Layer, Light, or Camera object

Example

// note this will match a layer with a comment "Controller" or "Motion Control"
thisComp.layerByComment("Control");