Adobe After Effects - Manual (Page 705)

Expression examples
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Online resources for expression examples
Expression example: Make a layer revolve in a circle
Expression example: Rotate the hands of a clock
Expression example: Position one layer between two others
Expression example: Create a trail of images
Expression example: Create a bulge between two layers
Expression example: Fade opacity of a 3D layer based on distance from camera
Expression example: Make a 3D layer invisible if facing away from camera
Expression example: Flip layer horizontally if facing away from camera
Expression example: Animate scale at each layer marker
Expression example: Start or stop wiggle at specific time
Expression example: Match camera focal plane to another layer
Many of the examples in this section are based on expressions provided by Dan Ebberts.
Online resources for expression examples
Dan Ebberts provides example expressions and tutorials for learning how to work with expressions on his MotionScript website . For example, Dan
provides an excellent page about collision detection .
Trish and Chris Meyer provide a series of articles about expressions on the ProVideo Coalition website . These articles contain many useful
examples.
Colin Braley provides a tutorial and example project on his website that show how to use expressions to make one layer repel others in a natural-
seeming manner.
The AE Enhancers forum provides many examples and much useful information about expressions, as well as scripts and animation presets. In
this post on the AE Enhancers forum , Paul Tuersley provides a tutorial and example project that show how to use expressions to animate several
layers in a swarm.
Rick Gerard provides an example on his website that demonstrates rolling a square object along a floor so that the sides stay in contact with the
floor plane.
Carl Larsen provides a video tutorial on the Creative COW website that demonstrates how to use expressions and parenting to relate the rotation
of a set of wheels to the horizontal movement of a vehicle.
Marcus Geduld provides some examples from his book, After Effects Expressions, on the Focal Press website. In the "String Manipulation" section,
Marcus shows how to use basic JavaScript to manipulate the text in the Source Text property of a layer. He even shows how to use an array of
strings so that a layer's Source Text property can be set to a specific word from a list. In the
"Physical Simulations" section, Marcus shows how to
use expressions for orbits, bounces, jiggles, and collision detection.
Chris Zwar provides an example project on his website for automatically arranging still images or videos into a grid (like a video wall). You can
easily adjust position and spacing with sliders that are connected to a system of expressions. There are three compositions in the project—one for
stills, one for videos, and one to create an auto-storyboard in which a video is sampled at user-defined intervals and aligned into a grid.
JJ Gifford’s website provides several example projects that demonstrate how to use expressions.
Rhys Enniks provides a video tutorial on his website in which he uses expressions and multiple text animators and range selectors to animate text
as if it is being typed onto a computer screen.
Maltaannon (Jerzy Drozda, Jr.) provides a video tutorial on his website that shows how to use expressions to create a volume meter using the
results of the Convert Audio To Keyframes command.
Harry Frank provides a tutorial on his graymachine website that shows how to use expressions to read data from an external text file.
Expression example: Make a layer revolve in a circle
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