Checkbox Control with more complex expression.

Adobe After Effects Expressions

Checkbox Control with more complex expression.

Posted by James McCavana on July 5, 2022 at 12:13 pm

Hello there,

I’m trying to enable/disable an expression with the Checkbox Control and can’t get it working. I found a few helpful threads on this forum but I keep getting errors. I think the errors occur due to my mis-handling of the – }else{value}; part of the expression.

Basically, I have this old favourite expression that I’m applying to layers (letters) as they whizz onto screen to form a text super.

// 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){

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);

amp = .02;

freq = 3.0;

decay = 5.0;

value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);

}else{

value;

}

But I’d like to disable the expression once the letters have settled so that the keyframed animation I have for when they LEAVE the screen is not affected by the bouncing.

I’ve tried and tried to get it set up correctly, but just can’t do it. Please could I have some help in setting this up?

Many thanks,

James.

James McCavana replied 4 years, 2 months ago 2 Members · 4 Replies
4 Replies

Dan Ebberts

July 5, 2022 at 3:17 pm

<div>This assumes that you’re using 2 keyframes to get your letters on screen, and gives the overshoot 2 seconds to settle out. If your conditions are different, you’ll need to adjust the second line:</div>

val = value;
if ((numKeys >= 2 && (time < key(2).time + 2)) || numKeys > 0){
  n = nearestKey(time).index;
  if (key(n).time > time) n--;
  t = n > 0 ? time - key(n).time : 0;
  if (n > 0 && t < 1){
    v = velocityAtTime(key(n).time - thisComp.frameDuration/10);
    amp = .02;
    freq = 3.0;
    decay = 5.0;
    val = value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
  }
}
val

James McCavana
July 5, 2022 at 4:22 pm

Hi Dan,

Thank you. I don’t understand what you mean. I’m just looking to toggle off the expression using the Checkbox Control. The expression is working just fine, I just can’t figure out how to place the bounce expression within the Checkbox Control expression.

Does that make sense?

Thanks.

Dan Ebberts

July 5, 2022 at 5:01 pm

Ah, OK. I think this should work:

cb = effect("Checkbox Control")("Checkbox").value;
if (cb){
  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);
    amp = .02;
    freq = 3.0;
    decay = 5.0;
    value + v*amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
  }else{
    value;
  }
}else{
  value;
}

James McCavana
July 5, 2022 at 5:19 pm

Hi again Dan, that’s perfect! Works exactly how I need it, thank you so much.

I just wanted to say… I’ve been using your expressions for many many years now, and you’re quite a legend! Thank you.

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