valueAtTime in both directions

[Julian Chojnacki]

Hi folks,

let’s say I have a keyframed animation that goes from 0 to -500 in Z space and back to 0 again and a layer that references that with valueAtTime and a -.1 delay.

I want the delay to adapt to the change of direction, which works with this code:

src=thisComp.layer(index-1)
v=src.transform.position.velocity;
let delay;
if(v[2] >= 0) {delay = -.1} else {delay = .1};
src.transform.position.valueAtTime(time-delay);

Unfortunately, this generates two problems:

1. On the first frame of the animation, which starts in the beginning of the comp, the position value jumps to -107.8, while it should be 0 since the animation it references is at 0 as well.
2. One frame before the -500 keyframe and the direction switch, the delayed layers jump values, which makes it look choppy like a few frames have been skipped, due to the nature of the adaptive delay, which switches values abruptly.

This code fixes the first problem:

const src=thisComp.layer(index-1);
const v = src.transform.position.velocity;
let delay;
if (time == 0){
    [value[0],value[1],value[2]];
}else{
    (v[2] >= 0) ? delay = -.1 : delay = .1;
    src.transform.position.valueAtTime(time-delay);
};

…but the other persists.

Any help would be fantastic 🙂

[Julian Chojnacki]

Update: cranking up the easing to 100 on the -500 keyframe fixed the problem…

[Max Haller]

see if this helps too

const src = thisComp.layer(index-1);
const v = src.transform.position.velocity;
let delay;
if (time == 0) {
  // Set the position to the initial value at time 0
  [value[0], value[1], value[2]];
} else {
  // Check if the velocity is greater than or equal to 0
  if (v[2] >= 0) {
    // If the velocity is positive, check if the previous delay value was negative
    if (delay < 0) {
      // If the previous delay was negative, interpolate between the previous value and -0.1 to smooth out the transition
      delay = linear(time, time-thisComp.frameDuration, time, delay, -0.1);
    } else {
      // If the previous delay was not negative, set the delay to -0.1
      delay = -0.1;
    }
  } else {
    // If the velocity is negative, check if the previous delay value was positive
    if (delay > 0) {
      // If the previous delay was positive, interpolate between the previous value and 0.1 to smooth out the transition
      delay = linear(time, time-thisComp.frameDuration, time, delay, 0.1);
    } else {
      // If the previous delay was not positive, set the delay to 0.1
      delay = 0.1;
    }
  }
  // Use the calculated delay value to get the position value at the current time
  src.transform.position.valueAtTime(time - delay);
}

[Julian Chojnacki]

Max, you nailed it! Thanks for the proper education 😉