Adobe After Effects CS3 User Manual
Page 562
AFTER EFFECTS CS3
User Guide
557
You can assign an Array to a variable, making it easy to refer to Array values in other areas of the expression. For
example:
myArray = [10, 23]
The dimension of an Array is the number of elements in the Array. The dimension of
myArray
is 2. Different
properties in After Effects have different dimensions depending on the number of value arguments they have. In the
expression language, properties’ values are either single values (Numbers) or Arrays.
The following table provides examples of some properties and their dimensions:
You can access the individual elements of an Array by using brackets and an index number to indicate which element
you want. The elements in an Array are indexed starting from 0. Using the previous example,
myArray[0]
is
10
and
myArray[1]
is
23
.
The following two expressions are equivalent:
[myArray[0], 5]
[10, 5]
The Position property arrays are indexed as follows:
•
position[0]
is the x coordinate of position.
•
position[1]
is the y coordinate of position.
•
position[2]
is the z coordinate of position.
Colors are represented as four-dimensional arrays [red, green, blue, alpha]. In projects with a color depth of 8 or 16
bpc, each value in a color array ranges from 0 (black) to 1 (white). For example, red can range from 0 (no color) to 1
(red). So, [0,0,0,0] is black and transparent, and [1,1,1,1] is white and completely opaque. In projects with a color
depth of 32 bpc, values under 0 and over 1 are allowed.
If you use an index that is greater than the index of the highest-dimension component in an Array, After Effects
returns an error. For example,
myArray[2]
causes an error, but
position[2]
returns the z coordinate of Position.
Many of the properties and methods in the After Effects expression language take Array objects as arguments or
return them as values. For example,
thisLayer.position
is an Array that is either two-dimensional or three-
dimensional depending on whether your layer is 2D or 3D.
If you want to write an expression that keeps the y value of an object’s animation but fixes the x value at 9, you would
use the following:
Dimension
Property
1
Rotation ˚
Opacity %
2
Scale [x=width, y=height]
Position [x, y]
Anchor Point [x, y]
3
Scale [width, height, depth]
3D Position [x, y, z]
3D Anchor Point [x, y, z]
4
Color [red, green, blue, alpha]