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free wiggle, rubber, bounce, throw, inertia expressions i find useful

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Chris Wright
free wiggle, rubber, bounce, throw, inertia expressions i find useful
on Oct 6, 2009 at 10:32:48 pm

These expressions save so much time, you might get home earlier tonight just by reading this post. If you've ever animated these sorts of things manually, you'll know what I mean. Most will need to be tweaked to your specific needs, but it's just a matter of playing with the numbers a little, and understanding how they'll change your animation. Here's the goods:

Jumpy Wiggle 1 makes wiggle skip and hold rather than move fluidly.

// Jumpy Wiggle 1 (moves at a random FPS)
if(v < 50)v=0;
if(v > 50)v=100;

Jumpy Wiggle 2 is similar to 1, but works at a defined FPS so your "jump" will happen at a regular pace.

// Jumpy Wiggle 2 (moves at a defined FPS)
fps=5; //frequency
amount=50; //amplitude
wiggle(fps,amount,octaves = 1, amp_mult = 0.5,(Math.round(time*fps))/fps);

Inertial Bounce is like making your moves "rubbery." Layers will overextend, then settle into place on position and rotation keyframes.

// Inertial Bounce (moves settle into place after bouncing around a little)
n = 0;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n).time > time){
if (n == 0){
t = 0;
t = time - key(n).time;

if (n > 0){
v = velocityAtTime(key(n).time - thisComp.frameDuration/10);
amp = .05;
freq = 4.0;
decay = 2.0;
value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);

Sometimes you just want something to move constantly without keyframing it. Use throw.

// Throw (move at a constant speed without keyframes)
veloc = -10; //horizontal velocity (pixels per second)
x = position[0] + (time - inPoint) *veloc;
y = position[1];

Same as throw, but for rotation.

// Spin (rotate at a constant speed without keyframes)
veloc = 360; //rotational velocity (degrees per second)
r = rotation + (time - inPoint) *veloc;

A shoutout to the brilliant folks at who provided in whole or in part the basis for all of these expressions.

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