After-Effects-Fun

After Effects Fun

Expressions, scripts and projects for Adobe After Effects.

Usually created by myself or others on the /r/AfterEffects Discord.

Projects

These were made using custom exploits!

Playable Pong (JavaScript only)

Drawing (JavaScript only)

Expressions

Tools

Image to expression converter

Global Variable Exploits

WARNING: These are all unpredictable to work with!

To have fun in After Effects, I often need to store data in memory and share it between expressions.

Often this is considered impossible, but there are several ways to do it:

1. Variable Leaking (JavaScript only)

I discovered variable names aren’t properly deleted by After Effects:

// Write a variable named "leak"
var leak = 5;

// Read all variable names
Object.keys(this); // ["leak"] (among others)

Variable names are shared between all expressions, and remain in memory until After Effects is restarted.

Object.keys(this) reads variable names, but not values. Therefore to store values, I put them in the name itself:

// Write a variable named "leak_5"
var leak_5;

eval() allows dynamic variable names:

// Write any variable name you want
const name = "hello";
eval(`var ${name}`);

To tell whether a variable is built-in, you can add a prefix:

// Add a "leak_" prefix to identify custom variables
const data = "hello";
eval(`var leak_${data}`);

// Read all variable names
Object.keys(this); // ["leak", "leak_5", "hello", "leak_hello"] (among others)

Using this concept, you can store multiple types of data in one variable name:

// Write 2 values into a single name
const writeX = 5;
const writeY = "hi";

eval(`var leak_${writeX}_${writeY}`);

// Read values by splitting
const parts = Object.keys(this).pop().split("_"); // ["leak", "5", "hi"]

const readX = parseInt(parts[1]); // 5
const readY = parts[2]; // "hi"

You can delete variable names like so:

// Delete variable named "leak_5_hi"
delete leak_5_hi;

Many characters aren’t allowed in variable names, so you have to be creative.

2. The Debug Object (JavaScript + ExtendScript)

@stibinator informed me of the debug object $.

$ is shared between all expressions, and remains in memory until After Effects is restarted.

// Write number
$.leak = 5;

// Read number
$.leak; // 5

Object.keys works on $:

// Read all keys
Object.keys($); // [{ leak: 5 }] (among others)

$ allows any type of data to be stored:

// Write complex data
$.leak2 = [
    {
        name: "Jeff",
        age: 20
    },
    {
        name: "Joe",
        age: 1
    }
];

// Read complex data
$.leak2; // [{ name: "Jeff", age: 20 }, { name: "Joe", age: 1 }]

$ allows custom keys:

// Write using a custom key
const key = "leak3";
$[key] = 123;

// Read using a custom key
$[key]; // 123

$ also works in ExtendScript, though Object.keys doesn’t.

3. Environment Variables (ExtendScript only)

I discovered ExtendScript has a method which sets environment variables:

$.setenv(key, value);

However it only writes string values:

$.setenv("leak", 5);
$.getenv("leak"); // "5"

Summary

Exploit	Engine	Get	Set	Capable of storing
Variable leaking	JavaScript	`Object.keys(this)`	eval(`var ${value}`)	Strings (excluding special characters)
The debug object	Both	`$.key`	`$.key = value`	Anything
Environment variables	ExtendScript	`$.getenv(key)`	`$.setenv(key, value)`	Strings

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