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Scale Expression with inertia bounce – start from zero
Hi everyone,
I have been using these forums for a long while and found them to be immeasurably helpful.
What I am trying to do now is get a layer to scale in and scale out at its in and out points, along with a bit of an inertia spring.
I have used one of Dan Ebberts scripts from one of the posts here and modified it a bit to work at in and out points.
The problem I am having is that the layer needs to be constantly re-sized to get somewhat reasonable results. Most of the time it bounces out OK although it never seems to really get to 0% scale. The in point is the one that doesn’t work properly though. Rarely can I get it to start at 0% scale. I have to have the layer scaled to the right size and tweak the ‘Scale’ setting in the expression. I normally have the variable set to sliders but have replaced them with my default settings here for easier dissecting.
I have the following script on a solid scaled at 40% in a 1050 x 576 comp. Solid was made comp size as I want this to work at any scale.
What I want to accomplish is to have the layer start at 0& scale and ramp up to whatever I set before applying the script. Then have a bit of inertia bounce that can be adjusted for intensity and length. At the minute the inertia bounce is working beautifully, I just need the scale to start and finish a 0%.
Then I want to be able to save it as a preset and have it save me hours of time over the next couple of years.
Really hope that I have made sense and that someone is able to tell me where I have gone wrong.
Regards
Justin Alexander
PS: Thanks to Roland R. Kahlenberg for pointing me to the correct forum for this issue
S =100; // Scale
A =20; // Amplitude
F =20; // Fequency
to = outPoint - time;
ti = time - inPoint;
inTrans = x=S*(1-Math.exp(-A*ti)*Math.cos(F*ti));
outTrans = y=S*(1-Math.exp(-A*to)*Math.cos(F*to));
value+ [inTrans,inTrans] + [outTrans,outTrans]; -
8 Replies
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I’m not sure this is what you’re describing, but give it a try and see if it’s close:
rate = 500;
rampDur = value[0]/rate;
freq = 3;
decay = 5;
w = freq*Math.PI*2;if (time < (inPoint+outPoint)/2){
if (time < (inPoint + rampDur)){
s = linear(time,inPoint,inPoint+rampDur,0,value[0]);
}else{
t = time - (inPoint+rampDur);
s = value[0] + rate*Math.sin(t*w)/Math.exp(t*decay)/w;
}
}else{
if (time > (outPoint - rampDur)){
s = linear(time,outPoint-rampDur,outPoint,value[0],0);
}else{
t = (outPoint - rampDur) - time;
s = value[0] + rate*Math.sin(t*w)/Math.exp(t*decay)/w;
}
}
[s,s]
Dan
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Hi Dan,
Thank you so much for solving my problem.
That is absolutely what I was after.
This will save me a heap of time over the next few yeas.
Much appreciated
Justin
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Hi. I’m researching how to get a star shape and a possibly a text layer (not sure if I’m going to have them connected or not) to “pop” up, hold for a second, so we can read the text and then pop back down to start position.
I like this bounce action. Thank you for the expression.
I put it on the P layer of the contents transform section…Should I put it on the P section of the Poystar path instead?
Either way. I’m wondering how to control the start/stop points and also to get the shape to bounce back to position after holding….
Any further assistance is greatly appreciated. Thank you very much.
rate = 500;
rampDur = value[0]/rate;
freq = 3;
decay = 5;
w = freq*Math.PI*2;if (time < (inPoint+outPoint)/2){
if (time < (inPoint + rampDur)){
s = linear(time,inPoint,inPoint+rampDur,0,value[0]);
}else{
t = time - (inPoint+rampDur);
s = value[0] + rate*Math.sin(t*w)/Math.exp(t*decay)/w;
}
}else{
if (time > (outPoint - rampDur)){
s = linear(time,outPoint-rampDur,outPoint,value[0],0);
}else{
t = (outPoint - rampDur) - time;
s = value[0] + rate*Math.sin(t*w)/Math.exp(t*decay)/w;
}
}
[s,s]Thank you!
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Figured it out with another expression I found. But would like to remove the bounce effect from the return movement and retain the initial movement 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){
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);
}else{
value;
}Thank you!
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Dan,
This exp looks and works great.
I’m just getting into AE and expressions and I was wondering what the proper steps to being able to use this script in reverse, or just be able to use this script going from any two sizes.
Like say I want to go from 100% to 20% and still retain the intertial bounce how would I edit your script.
I guess I just am not very good with changing variable and figuring out what they do.
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I think I would use the keyframe version of the expression for that (set linear keyframes for 100% and 20% the apply this expression to the scale property) :
freq = 3;
decay = 5;n = 0;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n).time > time) n--;
}
if (n > 0){
t = time - key(n).time;
amp = velocityAtTime(key(n).time - .001);
w = freq*Math.PI*2;
value + amp*(Math.sin(t*w)/Math.exp(decay*t)/w);
}else
value
More info here:
https://www.motionscript.com/articles/bounce-and-overshoot.html#kf-overshoot
Dan
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Dan
You are a good man!This is exactly what I was looking for. Thanks for all the help you provide to people like me and everyone in general 🙂
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I’ve been a big fan of this expression for some time now I’m just wondering if there’s a way that something can be added to it to make it scale back down to 0 after a set amount of time?
I’ve only been able to achieve this by attaching my objects to a null and then scaling the null down where I want the object to scale out. Any ideas?
Creative motion graphics, animation, video production and graphic design
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