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Create rotation bounce?
I’m trying to recreate the Kayak.com bumper. They have a flip board with cards that fall down. When the cards fall, they don’t swing all the way through (like a pendulum). Instead, they bounce off of the vertical plane and then come to rest after a decay. I’ve played with the bounce expressions, but can’t get it to work inside the X-rotation parameter.
I’ve cut the cards in half and made them 3D. Now I’m stuck with this expression. Any help would be awesome.
Here’s the video with the bumper at the end which I’m trying to recreate.
https://youtu.be/jj67ED3TzbE?hd=1Thanks!
-Brent
“For I know the plans I have for you,” declares the Lord, “plans to prosper you and not to harm you, plans to give you hope and a future.”
-Jeremiah 29:11 -
2 Replies
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the trick to get it to not swing through is to use Math.abs() to return only positive values so it will look like it bounces off something solid, rather than a free swing…
this is an expression i use for hard bounces. it does assume only two keyframes for the animation.. if there are more, the bounce will only happen after the last key.
k = .05; // spring constant
d = 10; // damping constant
freq = 4; // oscillation frequencyif (numKeys > 1){
if (time >= key(numKeys).time + (thisComp.frameDuration)){
t0 = key(numKeys).time;
t = time - t0;
v = velocityAtTime(t0)*(k*-Math.abs(Math.cos(freq * t * Math.PI * 2))/Math.exp(t*d));
valueAtTime(t0) + v;
}else{
value;
}
}else{
value;
}Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW -
forgot an else statement…
try this:
k = .05; // spring constant
d = 10; // damping constant
freq = 4; // oscillation frequencyif (numKeys > 1){
if (time >= key(numKeys).time + (thisComp.frameDuration)){
t0 = key(numKeys).time;
t = time - t0;
v = velocityAtTime(t0)*(k*-Math.abs(Math.cos(freq * t * Math.PI * 2))/Math.exp(t*d));
valueAtTime(t0) + v;
}else{
value;
}
}else{
value;
}Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW
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