time remapping with expression (?)

[Kalleheikki Kannisto]

Use the ease() expression instead of linear() and you will get a smoother result. You can set it up to ease at each end of the range.

Kalleheikki Kannisto
Senior Graphic Designer

[Ido Shor]

yes, I actually didn’t write my post properly…. I DID used the “Ease function” in my equation.
but it didn’t change or solve my issue.

thanks anyhow Kalle.

[Kalleheikki Kannisto]

Do you mean you have an expression that changes the value suddenly every 25 frames (like a hold keyframe) but you need the emitter to move smoothly between the positions?

Kalleheikki Kannisto
Senior Graphic Designer

[Ido Shor]

yes, that is the case.
exactly.

[Dan Ebberts]

Hard to say exactly, but probably something like this (not tested):

slider = ??; //(link to your slider here)
period = 25; // frames
tPeriod = framesToTime(25);
seg = Math.floor(time/tPeriod);
t = time%tPeriod;
v1 = slider.valueAtTime(seg*tPeriod);
v2 = slider.valueAtTime((seg+1)*tPeriod);
ease(t,0,tPeriod,v1,v2)

Dan

[Ido Shor]

Thanks Dan,

wiIll test that and come up with the results!

I can think of a few ways this script could come in handy…

cheers,
Ido

[Ido Shor]

Ok, Here are my foundlings

a graphical view of the behaviour of this expression:

the white line is the random value of the slider (with a posterizeTime expression added to change the value only every nth frame).
the green line represent the interpolation expression on the position.Y axis of the layer.

correct me if I am wrong, but it seems that the expression is generating the interpolation between two keyframes over a period of 25f, and not every 25f.

since the change is happening only every 25f, it needs to calculate it only between the 25th frame and the 26th frame and so on.

how can we achieve that?

cheers, Ido.

[Dan Ebberts]

You lost me. Can you draw what you want the result to look like?

Dan

[Ido Shor]

🙂

sure Dan,
what I am aiming at here is building a graph that will step forward every 25f, getting it’s values (the Y value that is), from a slider which has a random expression to it:

x = 25;
f = thisComp.frameDuration * x;
posterizeTime(1);
Math.round(random(300,600))

the object which generates the graph is an Emitter of Particles moving according to this expression.

so, I need this expression to get the values generated from the random slider, and add an ease interpolation, between each value change over a period of 25f. but at the same time, it has to keep still for 25f before moving on to the next keyframe…. (remember the steps?…)

that’s basically it.

cheers,
Ido.

[Kalleheikki Kannisto]

I think you’d get that if you change the posterize time value to 2, at which it would interpolate for 25 frames and hold the value for another 25 frames for a total of 50 frames per step.

Kalleheikki Kannisto
Senior Graphic Designer