Cookbook

Posted 2021, Updated on 10 Apr 2021
🔴 Why is my expression not working?
Biggest culprit: You are using ExtendScript for the Expression Engine, when it is supposed to be Javascript.

Fix: Go to File> Project Settings > Expressions > change to Javascript. (This option is available on AE 2019 and later.) 
Other reasons
You made a typo or used the wrong case when writing the variable or function names
You listed a single value into a parameters that takes an array 
eg. myScale =5  will yield an error because the scale property is an array that takes 2 values.
The fix is 
myScale = [5,5]; 
or myScale = 5; s = [myScale, myScale]
You forgot to put semicolons at the end of each line
You listed a variable as a string value 
This is a string: "mytext"
This is a variable: var str  = "mytext";
eg. in Apeel & Vucko tutorial, people alway list the variable as a string ('myVariable') when it should be just myVariable;
When to ask for help?
If you tried everything above, and nothing still works. There are two things you can do:
You can download the project files that I usually provide for free, and use my code I have there. As I am just a student, and do this on my own freewill. I do not have a lot of time and bandwidth to help people troubleshoot expressions. Hence, it's up to you to figure it on your own as much as possible.
If you have to ask me for help, what I appreciate is having more context and description of your problem. For example:
Which lines does the error occurred?
What does the error(s) say?
What have you tried? 
Have you consulted this guide and tried the solutions I mentioned?
What AE version are you running, and what OS.
Sample format for requesting troubleshooting
Hello, I having problem with line number. The error says errorMessage . I have tried solution but I still cannot fix the issue. 
What does not help me
Saying that "I wrote the code exactly" or I followed your tutorial. If you did, it would have worked. Clearly, the issue is something else and usually it's simply just a typo mistake.Hence, please give me more information about what the problem is so I can help you as quickly as possible.
More readings
​How to troubleshoot expressions errors, Intro to Expression Rigs in After Effects, Zack Lovatt
Phyllotaxis
//theta
var myIndex = index - thisComp.layer("controls").index;
var a = 137.508
var theta = degreesToRadians(myIndex * a);
​
theta
​
//position
var myIndex = index - thisComp.layer("controls").index;
var s = thisComp.layer("controls").effect("Spacing")("Slider");
var theta = effect("theta")("Slider");
​
x = s * Math.sqrt(myIndex) * Math.cos(theta);
y = s * Math.sqrt(myIndex) * Math.sin(theta);
​
[x, y] + [thisComp.width, thisComp.height] / 2
​
// Circle Size
var theta = effect("theta")("Slider");
var minSize = thisComp.layer("controls").effect("Min Size")("Slider");
var maxSize = thisComp.layer("controls").effect("Max Size")("Slider");
var maxRange = thisComp.layer("controls").effect("Distance Range")("Slider");
​
var sizeFactor = linear(theta, 0, maxRange, minSize, maxSize) / 100;
var s = thisComp.layer("controls").effect("Size")("Slider");
[s, s] * sizeFactor;
​
// Fill Color
var theta = effect("theta")("Slider");
var interval = thisComp.layer("controls").effect("Color Interval")("Slider");
var numColor = thisComp.layer("colors")("Effects").numProperties;
​
var colorIndex = Math.ceil(theta / interval) % numColor + 1;
thisComp.layer("colors").effect(colorIndex)("Color")
​
​
Best Motion Trails in After Effects
Wavey sine wave motion 
// apply to X position after separating dimensions
var vel = effect("waveSpeed")("Slider")*Math.PI*2;
var amp = effect("waveHeight")("Slider");
var offset =Math.PI*2*degreesToRadians(effect("phase")("Angle"));
​
// main 
var v = amp* Math.sin(time*vel+offset);
v + value;
createPath Motion Trails
//setup 
var l = effect("Layer Control")("Layer");
var dur = effect("trailLength")("Slider");
var pts = [];
​
// calculate the trail length in frame numbers 
var currentFrame = timeToFrames(time);
var trailLength = currentFrame - dur;
​
// main: generate the points from the current time 
​
for (i = currentFrame; i > trailLength; i--) {
    t = framesToTime(i)
    ap = l.toWorld(l.transform.anchorPoint, t);
    ap -= [thisComp.width, thisComp.height] / 2;
    pts.push(ap);
}
​
// create the path using the points
createPath(pts, [], [], 0)
Scaling Radial Grid
Parent/Child Link without scale inheritance
ps = parent.transform.scale.value;
s = value[0]*100/ps[0];
[s,s]
Aim Constraint
target = thisComp.layer("controls"); // set this to the layer to aim at
p = thisLayer.toWorld(anchorPoint) - target.position;
radiansToDegrees(Math.atan2(p[1], p[0])) - 90
Cyberpunk tech lines
main
branch
main
// user variables 
var pts = 50;
var pos = [0, 100];
var seed = 50;
​
// declaration 
var x, y; // coordinates
var c, mul; // direction changer
var vertices = [[0, 0]]; // create first point 
​
// vertices array 
for (i = 1; i <= pts; i++) {
  seedRandom(i + seed, true);
  c = random(); // create random num between 0 to 1 
  c > 0.5 ? mul = 1 : mul = -1; // change direction 
  oldEle = vertices[i - 1]; // get previous vertice
​
  y = random(pos[0], pos[1]);
  x = y * mul;
​
  // conditional: if even, go diagonal. If odd, go straight
  if (i % 2 == 0) {
    vertices[i] = oldEle + [x, y];
  } else {
    vertices[i] = oldEle + [0, y];
  }
}
​
createPath(vertices, [], [], 0);
branch
// user variables 
var pts = effect("pts")("Slider");
var pos = [effect("min_y")("Slider"), effect("max_y")("Slider")];
var seed = effect("seed")("Slider");
​
// get random point on first path
seedRandom(seed,true);
var myPath = content("main").path;
var myPathpts = myPath.points().length;
var myRandPt = Math.floor(random(myPathpts));
var mySelectedPt = myPath.points()[myRandPt];
​
// declaration 
var x, y // coordinates
var c, mul // direction changer
var vertices = [mySelectedPt] // create first point 
​
// vertices array 
for (i = 1; i <= pts; i++) {
  seedRandom(i + seed, true);
  c = random(); // create random num between 0 to 1 
  c > 0.5 ? mul = 1 : mul = -1; // change direction 
  oldEle = vertices[i - 1] // get previous vertice
​
  y = random(pos[0], pos[1]);
  x = y * mul;
​
  // conditional: if even, go diagonal. If odd, go straight
  if (i % 2 == 0) {
    vertices[i] = oldEle + [x, y];
  } else {
    vertices[i] = oldEle + [0, y];
  }
}
​
createPath(vertices, [], [], 0);
Radial Delay Rig
tgt = thisComp.layer("control");
// d = length(L.transform.position, transform.position);
d = length(thisLayer.toWorld(transform.anchorPoint), tgt.toWorld(tgt.transform.anchorPoint));
​
delay = thisComp.layer("control").effect("maxDelay")("Slider");
offset = linear(d,0,2000,0,delay);
time-offset;
Buck Apeel Circle Ripple
Ensure you have the following
ring shape layer Slider Controls : size,copies, radius (anchorpoint-Y), myIndex
null layer named "controls" with Slider Controls : circle_size, circle_spacing, ring_base_size, ring_spacing, dur
null layer named "colors" with Color Controls x 3
Auto-copies
cir = 2*Math.PI *effect("radius")("Slider"); // circumference of circle
n = thisComp.layer("controls").effect("circle_spacing")("Slider"); // max size of a circle
Math.floor(cir/n) // round down the results
Get myIndex
myIndex = index-thisComp.layer("controls").index-1;
Auto-scaling radius
myIndex = effect("myIndex")("Slider"); 
c = thisComp.layer("controls");
int = c.effect("ring_spacing")("Slider");
base = c.effect("ring_base_size")("Slider");
​
s = myIndex*int;s+ base;
Auto-alternate color
myIndex = effect("myIndex")("Slider"); 
num = myIndex %3+1;
thisComp.layer("color").effect(num)("Color")
Stagger-animation - balls
myIndex = effect("myIndex")("Slider"); 
s = thisComp.layer("controls").effect("circle_size")("Slider");
dur = framesToTime(thisComp.layer("controls").effect("dur")("Slider"));
offset = myIndex*dur;
s.valueAtTime(time-offset)
Matrix Binary Rain Code
seed = 10; // connect to slider
n = 50; // connect to slider
​
m = b = ''
​
for(i=0;i<n;i++){
	seedRandom(seed+i,true);
	b = Math.round(random());
	m += b;
}
Vucko — From Nothing to Something
Random flickering 
// apply this to your Time Remap property of your Sprite render 
seed = 20; // option:connect to a slider 
segMin = .5; //minimum segment duration
segMax = .8; //maximum segment duration
flickerDurMin = 1;
flickerDurMax = 5;
​
end = 0;
j = 0;
​
while ( time >= end){
  j += 1;
  seedRandom(j,true);
  start = end;
  end += random(segMin,segMax);
}
flickerDur = random(flickerDurMin,flickerDurMax);
if (time > end - flickerDur){
  seedRandom(j+69+seed,true);
  random(outPoint);
}else{
   seedRandom(j+seed,true);
  random(outPoint);
}
​
// original expression from Dan Ebbert
Falling leaves [1][2]
1
2
1
//position
yVelocity = 200; //pixels per second
oscFreq = 1.5; //oscillations per second
oscDepth = 35; //oscillation depth (pixels)
drift = 25; // drift (wind?) (pixels per second: - = left, + = right)
​
value + [oscDepth*Math.sin(oscFreq*Math.PI*2*time) + drift *time, yVelocity*time,0]
​
//Z ROTATION:
​
seedRandom(index,true);
random(360);
​
//Y ROTATION:
oscFreq = 1.5;
maxTilt = 15; //degrees
​
maxTilt*Math.cos(oscFreq*Math.PI*2*time)
2
yVelocity = 200; //pixels per second
oscFreq = 1.5; //oscillations per second
oscDepth = 35; //oscillation depth (pixels)
drift = 25; // drift (wind?) (pixels per second: - = left, + = right)
floor=500; //position of floor from top
​
X=value[0] + oscDepth*Math.sin(oscFreq*Math.PI*2*time) + drift *time;
Y=easeIn(value[1]+yVelocity*time,value[1],floor)
Z=0;
​
[X,Y,Z]
Techniques
Radial arrangement
​place along path  
Pixilation
Dot-Pixilation: CC Ball Actions
Square-Pixilation: Mosaic
Plugins: tv pixels,
Multi-image spriting / instancing
// Create a marker and use that to control the length of the comp you want instance
​
seedRandom(0,true);
m = thisComp.marker.nearestKey(time).time
random(0, m)
​
Type & Text
Algorithmic
Last updated 1 week ago