Useful Expressions - Adobe After Effects

Basic Expressions in After Effects

Here are some beginner-friendly expressions that you can use to add simple yet powerful animations and effects to your projects:

Tips for Using Expressions

• Alt/Option + Click on the stopwatch icon to open the expression editor for a property.

• Use the Pick Whip tool to easily link properties between layers.

• Test and tweak parameters (e.g., frequency, amplitude) for the desired effect.

• Comment your expressions for clarity using //.

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Wiggle (Random Movement)

wiggle(frequency, amplitude)

• Description: Creates random motion for a property.

• Example: wiggle(3, 50)

  
  

  Moves the layer randomly 3 times per second with an intensity of 50 pixels/units.

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Time (Linear Animation)

time * value

• Description: Animates a property over time.

• Example: time * 50

  
  

  Makes the property increase by 50 units every second.

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Loop Out (Repeating Keyframes)

loopOut(type = "cycle", numKeyframes = 0)

• Description: Repeats the keyframes indefinitely.

• Types:

  • "cycle": Loops keyframes in order.

  • "pingpong": Alternates back and forth.

  • "offset": Adds the last value to the start of the next loop.

  • "continue": Extends the motion beyond keyframes.

• Example: loopOut("pingpong")

  
  

  Creates a back-and-forth looping animation.

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Random (Generate Random Values)

random(minValue, maxValue)

• Description: Generates a random value between the specified range.

• Example: random(0, 360)

  
  

  Generates a random value between 0 and 360.

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Looping Wiggle (by Dan Ebberts)

freq = 1;
amp = 110;
loopTime = 3;
t = time % loopTime;
wiggle1 = wiggle(freq, amp, 1, 0.5, t);
wiggle2 = wiggle(freq, amp, 1, 0.5, t - loopTime);
linear(t, 0, loopTime, wiggle1, wiggle2)

• Description: Creates a smooth transition between values.

• Example: ease(time, 0, 100)

  
  

  Animates smoothly from 0 to 100.

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Value At Time (Offset Timing)

valueAtTime(time - offset)

• Description: Uses the property’s value from a different time.

• Example: valueAtTime(time - 0.5)

  
  

  Offsets the animation by half a second.

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Linear (Map One Range to Another)

linear(input, inputLow, inputHigh, outputLow, outputHigh)

• Description: Maps an input value from one range to another.

• Example: linear(time, 0, 1, 0, 100)

  Transitions from 0 to 100 over 1 second.

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Bounce

n = 0;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n).time > time){
n--;
}
}
if (n == 0){
t = 0;
}else{
t = time - key(n).time;
}
if (n > 0 && t < 1){
v = velocityAtTime(key(n).time - thisComp.frameDuration/10);
amp = .05;
freq = 4.0;
decay = 8.0;
value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
}else{
value;
}

• Description: Creates a bouncy effect after a keyframe.

• Example: Use this on position or scale for a spring-like bounce.

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Overshoot (by Dan Ebberts)

freq = 3;
decay = 5;

t = time - inPoint;
startVal = [0,0];
endVal = [200,200];
dur = 0.1;
if (t < dur){
  linear(t,0,dur,startVal,endVal);
}else{
  amp = (endVal - startVal)/dur;
  w = freq*Math.PI*2;
  endVal + amp*(Math.sin((t-dur)*w)/Math.exp(decay*(t-dur))/w);
}

• Description: Creates a bouncy effect after a keyframe.

• Example: Use this on position or scale for a spring-like bounce.

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Blinking Effect

frequency = 2;
Math.sin(time * frequency * Math.PI * 2) > 0 ? 100 : 0

• Description: It makes opacity blink on and off.

• Example: Use this on opacity to create a blinking effect at 2 times per second.

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Loop Path Keyframes

if (numKeys >1 && time > key(numKeys).time) {
 t1 = key(1).time;
 t2 = key(numKeys).time;
 span = t2 - t1;
 delta = time - t2;
 t = delta%span;
 valueAtTime(t1 + t)
} else {
	value
}

• Seamlessly loop keyframes on a Path Property for shape layers or masks.

• Behaves like loopOut('cycle')