Join Angie Taylor for an in-depth discussion in this video Varying a wiggle over time, part of After Effects Expressions for Premiere Pro Editors.
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In the previous tutorial, we had a look at how to wiggle a property or create random values. In this tutorial, we're going to have a look at how you can vary that wiggle over time. Now, you'll see that I've got a wiggle applied here. If I preview that, you'll see that it's wiggling constantly by the same amount throughout the whole animation but what if I want that value to reduce over time or to build over time. Well, there's a little trick to that and we do it using expression controllers. Now, you'll see I've got a Wiggle controller layer here and I've got two effects applied to that.
If I double click the Wiggle Frequency effect, these are just expression controllers that I've created by going to Effect, Expression Controls adding a slider and renaming them. What I want to do now is I want to get these values to control my wiggle value because these are key frameable which means I can actually animate these property values within the controller. So, how do we get that working? Well, let's have a look at the expression. We've got a one line expression just saying wiggle(10, 30.) What we're going to do is we're going to setup some variables.
So, I'm going to type in frequency. So, Freq will represent frequency = and then I'm going to pick whip up to the frequency slider value and then release it and that's going to place the address of that property, if you like, in after the equals sign. Just before I hit a carriage return, I'm going to add a semi-colon and then add a carriage return. So that's basically saying from now on when I type the word frequency, it will return this value which comes from here.
Then, we'll move onto a second line. So, let's add another carriage return and let's say Amp= and then we'll drag the pick whip up again. This time to the Wiggle Amplitude slider and then release it. So, from now on, the word amp typed exactly like that will return this value which comes from this slider. Now all I need to do is replace these numbers with my variables. So, I'll type in frequency which is the first value and I'll replace number 30 with Amp.
Now, you'll see we have it moving a lot more because look at our values. So, we've got a wiggle amplitude of 628 now but watch this. I can now just dial down that amplitude and see it updating immediately, a really nice way of working. So, rather than typing out lots of numbers into my wiggle, I can just adjust the slider and get immediate feedback with my live preview. If I want to increase the frequency, I can do that too.
Wiggle always looks better with motion blur. So, let's put motion blue on for the layer and for the comp and we can really get it going. So, I'm going to bring the value down for amplitude and let's put the amount up and we get a really crazy wiggle going on. Now, we wanted to figure out how to vary it over time. How's that done? Just by key framing these values. So, if I want to animate amplitude, for example, let's just stop playback for a second, move to two second mark and I'm just going to click on the Stopwatch for the Wiggle Amplitude value and that creates a key frame down in the timeline.
If I want to see that key frame, I can hit the u key to expose it or go to Animation, Reveal Properties with Keyframes. You can see now I've got an amplitude value being key framed and, if I want that to fade down to zero by seven seconds, all I do is move to seven seconds, type in zero and we should now have an extreme wiggle that reduces over time or varies over time. In the next tutorial, we'll have a look at how we can use this to create a camera shake effect.
After Effects Expressions for Premiere Pro Editors is a creative, project-based workshop. Editors take a basic Premiere Pro edit and bring it to life using After Effects expressions and Dynamic Link, following author Angie Taylor's expert instructions. The concepts are broken down into manageable 3–5 minute videos, covering techniques such as randomizing effects, linking animation and color to sound, automating animation, and more.
- Linking footage from Premiere Pro in After Effects with Dynamic Link
- Understanding the expression language
- Automating animation with expressions
- Randomizing effect properties
- Linking color and light changes to audio
- Creating camera shake with a wiggle expressions
- Linking keyframes to create a lightening strike effect
- Synchronizing color and other design elements
- Creating amazing text animations