In this tutorial I’m going to show you how to create flickering opacity transitions inside of Adobe After Effects. This is a pretty advanced technique which uses expressions, so if you’re too intimidated just download and use the free animation presets here -
I’ll be using these transitions to create an animated map for my vlogger friend Jay Swanson. More specifically, we’re attempting to create map animation intros for tour videos of each arrondissement of the city of Paris. Let’s get into it.
Step 1 - Wiggle the Opacity
For the first step, I’m going to use the ever-so-popular Wiggle expression. To keep things neat, I’ll add a Transform effect to my shape layer. I’ll hold Alt and click on the Opacity of the Transform effect to add an expression. Now I’ll type in the following -
Wiggle (freq,amp)
Instead of using numbers I’ve added freq and amp variables. Since these mean nothing for the moment, I’ll get an error message. To fix this, I’ll add two slider controls to my layer and rename them Frequency and Amplitude. To add these go to Effects > Expressions Controls > Slider Control. To get tight control over my flicker effect, I’ll connect my Opacity to the two slider controls via adding variables to the expression and assigning them to the sliders =
freq = effect("frequency")("Slider");
amp = effect("amplitude")("Slider");
wiggle(freq,amp)
I could just stop here and keyframe the sliders to create a very dynamic animation. However, I’d like to create something a little more versatile and interesting. In fact, I’d like to create something entirely without using keyframes.
Step 2 - Control the Wiggle with Time
To create a keyframe-less animation, I’ll use the powerful linear expression to control the amplitude slider. The expression below will not only animate the flicker in and out, it will attach those animations to the in and out points of the layer. This means that I can trim and move the layer as much as I want, and the animations will always follow the in and out points. Check out the expression here -
flickerIn = linear(time,inPoint,inPoint+1,100,0);
flickerOut = linear(time,outPoint-1,outPoint,0,100);
flickerIn+flickerOut
To see the specifics of how I put this expression together, be sure to check out my video tutorial above, where I also go into the specifics of how you can create your own animation presets.
If you’d like to learn more about the linear expression, check out this awesome deep-dive tutorial from Evan Abrams.
AND, if you’d like to become an expressions master, check out this premium course from Ukramedia. I’m currently taking this, and I’ve already learned so much.
If you’re looking for other resources, check out this list that I put together -
Expect to see more expression-related tutorials and freebies coming down the pipe soon.