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

Viewers:

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'm 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's doing but only do it half as much. Well that's what expressions are.

And they can come in extremely handy when you're 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 are a bit 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's a wide range of extremely useful expressions that you can use on 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're talking about elementary school math. Plus, minus, multiply, divide. There's even ways to get After Effects to do the math for you. So in this lesson I'm going to be showing you these introductory expressions that I think you'll 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 by 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'll not be getting all that deep or all that complex so there's no need to worry. These are simple things 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 deep into this great, powerful tool in After Effects know 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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