Adobe After Effects CS4 Uživatelský manuál stáhnout pdf (Strana 686)

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USING AFTER EFFECTS CS4

Expressions

Last updated 12/21/2009

Returns the MarkerKey object with this name. Use only on marker properties.

nearestKey(t) Return type: Key or MarkerKey.

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

numKeys Return type: Number.

Returns the number of keyframes on a property. Returns 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.

propertyGroup(countUp = 1) Return type: Group.

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.

This method is especially useful when duplicating properties that contain expressions.

The numProperties method for propertyGroup returns the number of properties in the property group.

This example returns the number of properties in the group that contains the property on which the expression is

written:

thisProperty.propertyGroup(1).numProperties

propertyIndex Return type: Number.

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.

name Return type: String.

Returns the name of the property or property group.

Example: Animating with the propertyGroup method and propertyIndex attribute

Values of propertyGroup relative to Position property of a brush stroke

A. propertyGroup(4) B. propertyGroup(3) C. propertyGroup(2) D. propertyGroup(1) E. Position propertyIndex value is 2; Rotation

propertyIndex value is 4.

In this example, the propertyGroup method for each brush stroke targets the Brush property group because that

group is two property groups up from the Rotation property. The

propertyIndex attribute in each Brush stroke then

returns a unique value for each Brush stroke. The resulting value is then multiplied by the time and 200 and applied

to each rotation value, rotating each brush stroke differently, creating swirling paint strokes:

propertyGroup(2).propertyIndex * time * 200

1 2 ... 681 682 683 684 685 686 687 688 689 690 691 ... 777 778

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