After Effects Apprentice 09: Expressions

with Chris Meyer and Trish Meyer
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After Effects Apprentice 09: Expressions
Video duration: 0s 1h 37m Intermediate Updated Nov 29, 2012

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Expressions are one of the most powerful but underused features in After Effects. They can be used to animate layer properties with code, as compared to explicitly keyframing every value in the Timeline, and have multiple parameters and layers that follow the lead of a master layer or controller effect, making it much easier to coordinate complex animations and quickly accommodate client changes. In this introduction, Chris Meyer shows how to let After Effects do most of the work by creating simple but very useful expressions that can be put to work on a wide variety of jobs.

The After Effects Apprentice videos on lynda.com were created by Trish and Chris Meyer and are designed to be used on their own and as a companion to their book After Effects Apprentice. We are honored to host these tutorials in the lynda.com Online Training Library®.

Topics include:
  • Creating and managing expressions
  • Linking together different parameters
  • Randomizing a layer's movement
  • Looping an animation
  • Controlling multiple layers from a single source
Subject:
Video
Software:
After Effects
Authors:

Overview

Hi, I am Chris Meyer of Crish Design, and welcome to the After Effects Apprentice lesson on expressions. Now, normally the way you animate a layer in After Effects is you use keyframing, where you say at this time, this parameter takes on this value. You set up multiple keyframes across time and After Effects will interpolate in between them for you. When it comes time to change the animation, you need to change the keyframes. However, there is another approach, where you give After Effects more general instructions, such as this layer should follow what that layer is doing, but only do it half as much. Well, that's what expressions are, and they come in extremely handy when you are trying to coordinate the movements of multiple parameters, or multiple layers, or trying to accommodate client changes on a deadline.

I know a lot of artists who have been intimidated by expressions because they associate them with programming and math, and it is true that expressions are based on the JavaScript programming language. However, there is a wide range of extremely useful expressions that you can use in almost any job that requires little or no programming on your part, and by programming, I mean typing a word like wiggle. That's as hard as it is. And as for the math part, we are talking about elementary school math: plus, minus, multiply, d ivide. There is even ways to get After Effects do the math for you.

So in this lesson I am going to be showing you these introductory expressions that I think you will find very useful. In this lesson, I'll be covering how to create and manage expressions, how to indeed use that simple elementary school math to modify them; how to take advantage of our three favorite intermediate-level expressions of linear interpolation, looping, and wiggle; how to set up a user interface for your expressions, how to set up master controls where one set of sliders can control multiple layers; and how to drive your animations via sound. We'll also have our usual list of Quizzler challenges and Idea Corners of how you can put these expressions to use.

Now again this is just an introductory course in expressions. We're not going to be getting into JavaScript programming. We are not going to be getting all that deep, or all that complex, so there is no need to worry. These are simple things that you can use on many, many different jobs. If you do want to take your expression skills to the next level, however, we do have another book called Creating Motion Graphics that has a couple of chapters that will take you deeper into this great powerful tool in After Effects known as expressions. But before I dive in, I want to show you what all can go wrong if you rely strictly on keyframes and don't take advantage of the power of expressions.

So, let's dive in and have some fun.

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Q: This course was updated on 11/29/2012. What changed?
A: We have added exercise files designed for After Effects CS6. We also added a movie that shows our premium subscribers how to use the exercise files.
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