Adobe After Effects - Expressions for newcomers: Wiggle

Like many things in Adobe After Effects, expressions are extremely powerful. Unfortunately, they can also appear to be the toughest to learn.

For many motion designers expressions are, in many ways, a shortcut for repetitive tasks. The Wiggle expression is no exception.

PART 1 - UNDERSTANDING THE POTENTIAL

Let's imagine we're animating an animal cell for an explainer animation. We've just imported our assets, now we need to give the shape the seemingly random movement. We could start with adding a few position keyframes, right?

So, why don't we add a whole bunch of position keyframes over a 5 second duration? Well, let's say we're using one keyframe every ten frames, that's already 15 manually placed keyframes. For most designers, this might equate to about 5 minutes of work. Let's reduce that to less than 30 seconds.

Using a Wiggle expression on the position property we can procedurally generate movement, removing any custom manually placed keyframes.

1.

Find the layer we need to animate. Open the layer Transformation options.

2.

ALT Clicking on the Position stopwatch will open the dialogue box within the timeline window.

3.

Enter the following text: wiggle(1,60)

4.

Once the text is entered, click outside the dialogue box to close the entry.

5.

With the expression working, the position values will change over time. Any valve affected by an expression will displayed in red type.

Quick note: Wiggle (x, y) x = Frequency y = Magnitude

Great, we've done it! Let's move onto a slightly more complex scenario.

PART 2 - TAMING THE BEAST

The next scene requires the same cell to transition from an excited to a relaxed state. Unfortunately, using the previous technique won't give us the ability to alter the expression values over time. This means we're stuck with the same movement. To amend this, we can use another tool in conjunction with the expression.

The Slider Control is a very effective way to feed values into an expression. Because these values are linked, we only need to keyframe the values within the Slider Control layer itself.

1.

Add two Slider Control effects onto the layer we need to animate. This effect can also be found here: Effect > Expression Controls > Slider Controls

2.

Rename the effects to Frequency Control & Magnitude Control, respectively.

3.

Return back to the Position value and ALT Click on the stopwatch.

4.

Enter the following: wiggle(0,0)

5.

Highlight the first zero. Then, using the adjacent Pick Wip, connect to Frequency Control we created previously.

6.

Repeat the previous step using with the remaining zero and connecting Magnitude Control.

The Position dialog box should read the following: wiggle(effect("Frequency Control")("Slider"),effect("Magnitude Control")("Slider"))

7.

Add a new keyframe for each Control at the start of the timeline. Use the following values: 2 and 180

8.

Add another keyframe towards then end of the timeline. Use the following values: .5 and 10

Great, now let's use these two techniques together with another element.

PART 3 - HARNESSING THE POWER

For our final scene, the client has requested to illustrate the cell moving across the screen while transitioning from an excited to a relaxed state. Unless we pre-comp the layer, we will have a hard time getting the cell across the screen at all. We will need a stand-in: a Null Layer.

Null Layers are the roto painters of the film industry; their footprint is impossible to spot, yet they are one of the most crucial elements. Within After Effects, we can use Null Layers to tie together layer hierarchy. Since we’re only starting out with expressions, we are only going to use the Null Layer to control the position of our cell.

1.

Create a Null Layer, then rename to: CELL NULL

2.

Using the Pick Whip, connect the layer we are animated to the new Null Layer.

Great! We're done! We've been using the Wiggle expression exclusively with the position value. We can use the same approach with any of the alternate transform priorities. If you’re feeling adventurous, have a go putting in your own Frequency & Magnitude values!

If you want to learn more about expressions within Adobe After Effects, check out the pages below:
https://helpx.adobe.com/after-effects/using/expression-basics.html
http://expressions.aenhancers.com/