Use expressions to create movement without keyframes

In this exercise we're going to add more interest and intensity to our type by animating a flickering glow without using any keyframes.

To start let's look at how this graphic is built.

Layer 1 is red type.

If I turn that visibility off, you can see it's got a black drop shadow.

Under there it has a white outline.

Under that I have a burst and under there is our background.

Now I will turn the visibility of all these layers back on and I want to change the white to a glow.

So, let's select Layer 3 the POW!

white layer and then go up under the Effect menu, go to Blur & Sharpen and choose Fast Box Blur.

Change the Blur Radius setting to a value of 7.0 and you can see now we've got a nice blurry glow.

To create animation instead of adding keyframes we’ll add an expression.

On Windows, hold down Alt, on Mac hold down Option and click on the stopwatch next to the Blur Radius to automatically add the expression.

Notice now when we go to the Timeline here under Blur Radius it says Expression Blur Radius.

On the right I have a text editing area and rather than clicking inside of there I'm just automatically going to start typing and I'm going to add a wiggle expression.

So, I'll start by typing the word wiggle W-I-G-G-L-E and then we'll choose a left paren and I want it to wiggle 20 times a second, so I'll type 20 and then I'll press , and I only want it to wiggle the value up or down about 5 points.

So, I'll say 5 and then let's choose the right paren here and click anywhere outside of this white line to set the wiggle expression.

Now if we press the Spacebar, you'll notice the glow is actually wiggling and if I press the Spacebar again it'll stop playback.

Now, that's one way to create an expression, write it from scratch.

Another way is to actually have one parameter of any layer or effect get driven by another one.

So, what we'll do is adjust the rotation of the drop shadow based on the intensity of the Blur Radius.

So, I'll select Layer 2 and press R to open its Rotation.

Now if you notice next to Rotation if we go over the Parent & Link column indented here is a pick-whip and that's for the rotation.

I want this Rotation value to match the Blur Radius.

So, I'll click on the pick-whip, hold my mouse down and drag and point it to the Blur Radius, and when I let go, this is automatically going to create an expression and I know an expression has been applied because I can see the numbers turn red.

Also, to the left of the keyframe button here there is an arrow.

So, if we open the arrow here you can see there's an Expression to the Rotation and it's saying in this Comp.layer ("POW!

white"), we're going to look at the Effect for the Fast Box Blur based on the Blur Radius.

So, notice they match perfectly.

If I press the Spacebar, it's going to go ahead and rotate at the same intensity as the glow.

Now, this looks a little rough.

I don't want it to rotate nearly as much but I still want it to rotate in sync with the wiggle in the glow.

So, I'll press the Spacebar to stop playback and I'll click once anywhere in the type here for the Expression for the Rotation.

That will select all the letters on the type, and I'll click to the right.

Then I'll use the / button and type 10 and what I'm saying is I want this expression to be divided by 10.

So, it's only going to be one-tenth as strong as the Blur Radius.

So, when I click outside of there notice this is set to 8.1 and here now it's 0.8.

So, if I press the Spacebar again, you can see now I have my rotation flickering at the same velocity just not nearly as much.

So, as you can see Expressions allow you to create dynamic animation quickly without the use of keyframes.