User Guide

CHAPTER 10
312
Creating Expressions
Converting expressions to keyframes
In some situations, it may be useful to convert an expression to keyframes. For example,
if you want to freeze the values in an expression for a period of time, you can convert the
expression to keyframes and then adjust the keyframes accordingly; if an expression takes
a long time to evaluate, you can convert it to keyframes so that it renders faster. When you
convert to keyframes, After Effects evaluates the expression, creating a keyframe at every
frame, and then disables the expression.
To convert an expression to keyframes:
In the Timeline window, select the property in which the expression is written and choose
Animation > Keyframe Assistant > Convert Expression to Keyframes.
Creating expressions with the pick whip
Use the pick whip to create expressions that link the values of one property or effect to
another. For example, link the Rotation property of layer 1 to the Rotation property of
layer 2 to make layer 1’s rotation values the same as layer 2’s; or, link a camera’s Point of
Interest property to the Position property of another 3D layer to make the camera follow
the layer as it moves through space.
Selecting properties and values with the pick whip
To use the pick whip, click the pick whip icon ( ) and drag it to another property or to a
specific property value. Once you select a property or value, After Effects automatically
inserts the appropriate expression in the expression field at the location of the cursor; if text
is already selected in the expression field, that text is replaced by the new expression text. If
the cursor is not in the expression field, all text in the field is replaced by the new text.
UG.book Page 312 Wednesday, February 21, 2001 12:05 PM