property

Property

This category holds generic entries relating to generic properties.

In expressions, a Property is typically anything that exists in the timeline (even if it can’t be keyframed, or hold an expression).

??? example “Examples of Properties”

All of the following AE items are actually "Properties" for the use of expressions, along with *some* ways to access those properties by code:

- Position (`thisLayer.transform.position`, `layer.position`)
- Scale (`thisLayer.transform.scale`, `layer.scale`)
- A slider effect's *actual slider* (`effect("Slider Control")("Slider")`, `effect("Slider Control")(1)`)
- A text layer's [Text](../../text/text) property (`thisLayer.text`)
    - *Note that in this case, Text also has its own special items, found in the above link.*

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

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Attributes

name

thisLayer.position.name

Description

Returns the name of the property or property group.

Type

String

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numKeys

thisLayer.position.numKeys

Description

Returns the number of keyframes on a property, or the number of markers on a marker property.

Note

If you use the Separate Dimensions command to separate the dimensions of the Position property into individual components, the number of keyframes changes, so the value returned by this method changes.

Type

Number

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propertyIndex

thisLayer.position.propertyIndex

Description

Returns the index of a property relative to other properties in its property group, including property groups within masks, effects, text animators, selectors, shapes, trackers, and track points.

Type

Number

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speed

thisLayer.position.speed

Description

Returns a 1-dimensional, positive speed value equal to the speed at which the property is changing at the default time.

Note

This can be used only for spatial properties.

Type

Number

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value

thisLayer.position.value

Description

Returns the value of a property at the current time.

Type

Number, Array, or String

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velocity

thisLayer.position.velocity

Description

Returns the temporal velocity value at the current time. For spatial properties, such as Position, it returns the tangent vector value. The result is the same dimension as the property.

Type

Number or Array

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Methods

key()

thisLayer.position.key(index)

Description

Returns the Key or MarkerKey object by index number.

Parameters

Parameter	Type	Description
index	Number	The key (or MarkerKey) index number

Returns

Key or MarkerKey

Example

To retrieve the first keyframe on a property:

thisLayer.scale.key(1);

To retrieve the last keyframe on a property:

thisLayer.rotation.key(thisLayer.rotation.numKeys);

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key()

thisLayer.position.key(markerName)

Description

Returns the MarkerKey object with this name.

Note

This can be used only on marker properties.

Parameters

Parameter	Type	Description
markerName	String	The name of the marker to return the matching key of.

Returns

MarkerKey

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loopIn()

thisLayer.position.loopIn([type="cycle"][, numKeyframes=0])

Description

Loops a segment of time that is measured from the first keyframe on the layer forward toward the Out point of the layer. The loop plays from the In point of the layer.

You can use keyframe-looping methods to repeat a series of keyframes. You can use these methods on most properties. Exceptions include: - properties that can’t be expressed by simple numeric values in the Timeline panel, such as: - the Source Text property, - path shape properties, and - the Histogram property for the Levels effect.

Keyframes or duration values that are too large are clipped to the maximum allowable value. Values that are too small result in a constant loop.

Parameters

Parameter	Type	Description
type	Predefined string as defined in Loop Types	Optional. The loop type to use. Defaults to "cycle"
numKeyframes	Number	Optional. The segment to loop, from keyframe #1 to keyframe #numKeyframes + 1. If unspecified (or 0), all keyframes loop. Defaults to 0.

Returns

A looped value of the same property type as this current property.

Example

To loop the segment bounded by the first and fourth keyframes:

loopIn("cycle", 3);

To loop forward and backward indefinitely from your current keyframes:

loopIn("continue") + loopOut("continue") - value;

Note that we need to subtract value, because both loopIn() and loopOut() include the current value; by adding them, we have two copies of the current value, and need to remove one (the - value) to get back to the proper keyframe value.

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loopInDuration()

thisLayer.position.loopInDuration([type="cycle"][, duration=0])

Description

Loops a segment of time that is measured from the first keyframe on the layer forward toward the Out point of the layer.

Parameters

Parameter	Type	Description
type	Predefined string as defined in Loop Types	Optional. The loop type to use. Defaults to "cycle"
duration	Number	Optional. The number of composition seconds in a segment to loop, measured from the first keyframe. If unspecified (or 0), the segment to loop begins at the layer Out point. Defaults to 0.

Returns

A looped value of the same property type as this current property.

Example

To loop the first second of the entire animation:

loopInDuration("cycle", 1);

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loopOut()

thisLayer.position.loopOut([type="cycle"][, numKeyframes=0])

Description

Loops a segment of time that is measured from the last keyframe on the layer back toward the In point of the layer. The loop plays until the Out point of the layer.

David Van Brink provides an instructional article and sample project on his omino pixel blog that show how to use the Echo effect, the Particle Playground effect, and the loopOut() method to animate a swarm of stylized swimming bacteria.

Parameters

Parameter	Type	Description
type	Predefined string as defined in Loop Types	Optional. The loop type to use. Defaults to "cycle"
numKeyframes	Number	Optional. The segment to loop, measured backward from the last keyframe. If unspecified (or 0), all keyframes loop. Defaults to 0.

Returns

A looped value of the same property type as this current property.

Example

To loop the segment bounded by the last keyframe and second-to-last keyframe:

loopOut("cycle", 1);

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loopOutDuration()

thisLayer.position.loopOutDuration([type="cycle"][, duration=0])

Description

Loops a segment of time that is measured from the last keyframe on the layer back toward the In point of the layer. The loop plays until the Out point of the layer.

Parameters

Parameter	Type	Description
type	Predefined string as defined in Loop Types	Optional. The loop type to use. Defaults to "cycle"
duration	Number	Optional. The number of composition seconds in a segment to loop, measured backward from the last keyframe. If unspecified (or 0), the segment to loop begins at the layer In point. Defaults to 0.

Returns

A looped value of the same property type as this current property.

Example

To loop the last second of the entire animation:

loopOutDuration("cycle", 1);

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nearestKey()

thisLayer.position.nearestKey(t)

Description

Returns the Key or MarkerKey object nearest to a designated time t.

Parameters

Parameter	Type	Description
t	Number	The time to find the nearest key from

Returns

Key or MarkerKey

Example

Get the nearest keyframe to the 2-second time in the comp:

const twoSecondKey = thisLayer.scale.nearestKey(2);

// and then, to get the value of that key:
twoSecondKey.value;

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propertyGroup()

thisLayer.position.propertyGroup([countUp=1])

Description

Returns a group of properties relative to the property on which the expression is written.

For example, if you add the propertyGroup(1) expression to the Rotation property of a brush stroke, the expression targets the Transform property group, which contains the Rotation property. If you add propertyGroup(2) instead, the expression targets the Brush property group.

This method lets you establish name-independent relationships in the property hierarchy. It is especially useful when duplicating properties that contain expressions.The numProperties method for propertyGroup returns the number of properties in the property group.

Parameters

Parameter	Type	Description
countUp	Number	Optional. The number of property groups “up” the hierarchy to climb. Defaults to 1.

Returns

PropertyGroup object

Example

Return the number of properties in the group that contains the property on which this expression is written:

thisProperty.propertyGroup(1).numProperties;

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smooth()

thisLayer.position.smooth([width=.2][, samples=5][, t=time])

Description

Smooths the property values over time, converting large, brief deviations in the value to smaller, more evenly distributed deviations. This smoothing is accomplished by applying a box filter to the value of the property at the specified time.

Parameters

Parameter	Type	Description
width	Number	Optional. The range of time (in seconds) over which the filter is averaged. Defaults to 0.2.
samples	Number	Optional. The number of discrete samples evenly spaced over time. Use a larger value for greater smoothness (but decreased performance). Defaults to 5.
		Generally, you’ll want samples to be an odd number so that the value at the current time is included in the average.
t	Number	Optional. The specified time (in comp seconds) to apply the smoothing filter to. Defaults to time (the current comp time, in seconds).

Returns

Number or Array

Example

To smooth a position property’s animation:

position.smooth(0.1, 5)

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speedAtTime()

thisLayer.position.speedAtTime(t)

Description

Returns the spatial speed value at the specified time.

Parameters

Parameter	Type	Description
t	Number	The specified time at which to get the spatial speed value.

Returns

Number

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temporalWiggle()

thisLayer.position.temporalWiggle(freq, amp[, octaves=1][, amp_mult=0.5][, t=time])

Description

Samples the property at a wiggled time.

For this function to be meaningful, the property it samples must be animated, because the function alters only the time of sampling, not the value.

Parameters

Parameter	Type	Description
freq	Number	The frequency, in wiggles per second.
amp	Number	The amplitude, in units of the property to which it is applied.
octaves	Number	Optional. The number of octaves of noise to add together. Defaults to 1.
amp_mult	Number	Optional. The amount that amp is multiplied by for each octave. Defaults to 0.5.
t	Number	Optional. The base start time. Defaults to time (the current comp time, in seconds).

Returns

Number or Array

Example

To add a temporal wiggle to scale:

scale.temporalWiggle(5, 0.2)

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valueAtTime()

thisLayer.position.valueAtTime(t)

Description

Returns the value of a property at the specified time, in seconds.

Note

Dan Ebberts provides more examples and techniques for using the valueAtTime and velocityAtTime methods on MotionScript.

Parameters

Parameter	Type	Description
t	Number	The time, in seconds, to get the value from

Returns

Number or Array

Example

For example, to have a property value for each frame chosen randomly from a set of four values, set your four values as keyframes at 0, 1, 2, and 3 seconds, and then apply the following expression to the property:

valueAtTime(random(4))

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velocityAtTime()

thisLayer.position.velocityAtTime(t)

Description

Returns the temporal velocity value at the specified time.

Parameters

Parameter	Type	Description
t	Number	The time, in seconds, to get the temporal velocity from

Returns

Number or Array

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wiggle()

thisLayer.position.wiggle(freq, amp[, octaves=1][, amp_mult=0.5][, t=time])

Description

Randomly shakes (wiggles) the value of the property.

Note

Dan Ebberts provides an example expression and a detailed explanation on his website that shows how to use the time parameter of the wiggle method to create a looping animation.

Parameters

Parameter	Type	Description
freq	Number	Frequency, in wiggles per second.
amp	Number	Amplitude, in units of the property to which it is applied.
octaves	Number	Optional. Number of octaves of noise to add together. This value controls how much detail is in the wiggle.
		Make this value higher than the default to include higher frequencies or lower to include amplitude harmonics in the wiggle. Defaults to 1.
amp_mult	Number	Optional. Amount that amp is multiplied by for each octave. This value controls how fast the harmonics drop off.
		Make this value closer to 1 to have the harmonics added at the same amplitude as the base frequency, or closer to 0 to add in less detail. Defaults to 0.5.
t	Number	Optional. Base start time. This value defaults to the current time. Use this parameter if you want the output to be a wiggle of the property value sampled at a different time. Defaults to time (the current comp time, in seconds).

Returns

Number or Array

Example

This produces about 5 wiggles per second with an average size of about 20 pixels. In addition to the main wiggle, two more levels of detailed wiggles occur with a frequency of 10 and 20 wiggles per second, and sizes of 10 and 5 pixels, respectively:

position.wiggle(5, 20, 3, 0.5);

This example, on a two-dimensional property such as Scale, wiggles both dimensions by the same amount:

const v = wiggle(5, 10);

[v[0], v[0]];

This example, on a two-dimensional property, wiggles only along the y-axis:

const freq = 3;
const amp = 50;
const w = wiggle(freq,amp);

[value[0], w[1]];

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Loop Types

The following loop types are predefined strings used in the “type” parameter for:

• loopIn()
• loopInDuration()
• loopOut()
• loopOutDuration()

Type	Behaviour
"cycle"	Default. Repeats the specified segment.
"pingpong"	Repeats the specified segment, alternating between forward and backward.
"offset"	Repeats the specified segment, but offsets each cycle by the difference in the value of the property at the start and end of the segment, multiplied by the number of times the segment has looped.
"continue"	Does not repeat the specified segment, but continues to animate a property based on the velocity at the first or last keyframe.
	For example, if the last keyframe of a Scale property of a layer is 100%, the layer continues to scale from 100% to the Out point, instead of looping directly back to the Out point. This type does not accept a keyframes or duration argument.