Adjusting a layers’ scale based on another layers’ alpha

[Dan Ebberts]

I think this is what you’re looking for. You might have to reverse minScale and maxScale in the last line.

M = thisComp.layer(“Matte”);
minScale = [0,0];
maxScale = [100,100];
p = M.fromComp(toComp(anchorPoint));
a = M.sampleImage(p,[.5,.5],true,time)[3];
linear(a,0,1,maxScale,minScale)

Dan

[Stefan Hinze]

i can not give you the complet awnser, but i can tell you how i would try.

one:
Epression
maybe with some “SambleImage”

two:
by using “card-dance” and the currend comp as a driver

as i am writing i think two is the better way!
hope this helps

greetz

[Adam Buritsch]

Perfect! Thank you Dan, that was exactly the ticket!

And Stefan, that card dance idea is a smart approach for this project. I should have thought of that, but it will most likely help me with other aspects of this same project. Thanks to you both for the helpful and prompt answers!

[Jamie Shiels]

Hi Dan,

Is it possible to use this but with a inertial bounce similar to this expression?

Thanks

Jamie

// Inertial Easing (elastically reacts to the speed at which it was animated)
amp = .1;
freq = 2.0;
decay = 2.0;
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);
value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
}else{
value
}


[Dan Ebberts]

Hard to say. It depends on what’s driving the alpha change. Is it keyframes somewhere, or something else?

Dan

[Jamie Shiels]

I would be using a precomp, the same size as the main comp with animated shape layers to control the scale of the objects in the main comp.

[Dan Ebberts]

That makes it complicated. Somehow you have to come up with the velocity of the alpha change to drive the overshoot oscillation. Or, you could detect the alpha exceeding some threshold and use that event to trigger your scale-up animation (including the overshoot). Hard to say exactly without knowing all the details. I think it can be done, but it’s not simple.

Dan

[Jamie Shiels]

Thanks for looking into this Dan, I will find another workaround.

Cheers

Jamie