Modify Expand Contract expression

[Dan Ebberts]

This should do it:

maxDev = 10; // max deviation in pixels
spd = 20; //speed of oscillation
decay = 1.0; //how fast it slows down

if (marker.numKeys > 0){
t = time – marker.key(1).time;
if (t >=0 ){
y = scale[0] + maxDev*Math.sin(spd*t)/Math.exp(decay*t);
[value[0],y]
}else{
value
}
}else{
value
}

Dan

[Zach Meissner]

Thanks Dan! Is there an easy way to disable the expression with a another layer marker, or with a checkbox control? I want to change just the Y value of text to make appear to sink into the ground at a certain time, but i cant keyframe the scale because the expression is in use. I figure it’s easy to do with a layer marker but i wasn’t sure how. Thanks a bunch!!

[Dan Ebberts]

Ah, I think that’s because there’s an error in the expression. Try changing the long line to this:

y = scale[1] + maxDev*Math.sin(spd*t)/Math.exp(decay*t);

That should keep everything live for keyframing.

Dan

[Zach Meissner]

Yes!! Thanks so much Dan!!

[Zach Meissner]

Hey Dan, if i wanted to turn the expression on again at another layer marker, how would i modify it? I’m thinking something with the ‘key(1)’ text, but i’m not sure. Thanks!

[Dan Ebberts]

This should trigger at each layer marker:

maxDev = 10; // max deviation in pixels
spd = 20; //speed of oscillation
decay = 1.0; //how fast it slows down

n = 0;
if (marker.numKeys > 0){
n = marker.nearestKey(time).index;
if (marker.key(n).time > time){
n–;
}
}

if (n > 0){
t = time – marker.key(n).time;
y = scale[1] + maxDev*Math.sin(spd*t)/Math.exp(decay*t);
[value[0],y]
}else{
value
}

Dan

[Zach Meissner]

Thanks so much Dan!!!

[Zach Meissner]

Hi Dan, back again. Trying to get this to only be on the X axis. I’ve replaced the X and Y text, but that didn’t work.

How can I get the expression to only do the x and not the y?

maxDev = 10; // max deviation in pixels
spd = 20; //speed of oscillation
decay = 1.0; //how fast it slows down

n = 0;
if (marker.numKeys > 0){
n = marker.nearestKey(time).index;
if (marker.key(n).time > time){
n--;
}
}

if (n > 0){
t = time - marker.key(n).time;
y = scale[1] + maxDev*Math.sin(spd*t)/Math.exp(decay*t);
[value[0],y]
}else{
value
}


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