animating position at fixed intervals with fixed values

[Xinlai Ni]

Try this:
timeToClimb = 1;
timeToStay = 2;
initialY = 243;
positionY = initialY - 5 * Math.floor(time / (timeToClimb + timeToStay));
t = time % (timeToClimb + timeToStay);
[432, linear(t, 0, timeToClimb, positionY, positionY - 5)]

Xinlai Ni
Software Engineer, Google Inc.

[Dan Ebberts]

It will be something like this:

moveTime = .3;
holdTime = 4.7;
delta = [0,-5];

seg = Math.floor(time/(moveTime+holdTime));
t = time % (moveTime+holdTime);
value + delta*seg + linear(t,holdTime,holdTime+moveTime,0,delta)

Dan

[Jonathan Reyes]

Thank you both! Works like a charm! If you have some time, could you explain what’s happening here? I know some basic expressions, but am by no means an expert (or even a novice for that matter) and I like to know how things work before i implement them in my projects. Also, using this method, is it possible to “ease” the animation of the position? thank you!!

[Dan Ebberts]

Wherever you see “linear”, just change it to “ease”.

I wish I had time to explain how it works, but I’m pretty jammed up this week.

Dan

[Jonathan Reyes]

Thanks again for this wonderful expression. However, I was wondering how I can apply to this to time. For example, I have a clip that I want to Time Remap where it plays for 1 second, pauses for 5 seconds, resumes play for 1 second, pauses for another 5 seconds, etc. It seems like this expression would work with some tweaks, unfortunately I’m not the best at this and can’t figure it out. any help would be appreciated, thanks!

[Dan Ebberts]

Try this:

moveTime = 1;
holdTime = 5;

seg = Math.floor(time/(moveTime+holdTime));
t = Math.min(time % (moveTime+holdTime),moveTime);
seg*moveTime + t

Dan

[Jonathan Reyes]

Thanks very much Dan! works perfectly!

[Sebastian Heinrich]

Hi,
I am quite a noob when it comes to expressions.
Basically what I am trying to achieve is to connect your Expression (what perfectly does what I need) with an inertial Bounce.
I want a layer to move in fixed intervals but also have a bounce at the end position. And I don’t want to use keyframes.
I have been using the inertial Bounce Expression from Graymachine which is based on keyframes.
But I am to stupid to find a way to connect these Expressions.
Do you know how to do this?

Thank you!

So I want to connect this:

timeToClimb = 1;
timeToStay = 2;
initialY = 243;
positionY = initialY - 5 * Math.floor(time / (timeToClimb + timeToStay));
t = time % (timeToClimb + timeToStay);
[432, linear(t, 0, timeToClimb, positionY, positionY - 5)]

with this:

amp = .05;
freq = 1.0;
decay = 4.0;

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){
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]

I think this gives you the appropriate overshoot, but I don’t think you’re going to see much bounce with a velocity of 5 px/sec:


timeToClimb = 1;
timeToStay = 2;
step = 5;
initialY =243;
positionY = initialY - step * Math.floor(time / (timeToClimb + timeToStay));
t = time % (timeToClimb + timeToStay);

freq = 1;
decay = 2;

if (t < timeToClimb){
[432,linear( t, 0, timeToClimb, positionY, positionY - step)];
}else{
amp = step/timeToClimb;
w = freq*Math.PI*2;
[432,positionY - step] - [0,amp*(Math.sin((t-timeToClimb)*w)/Math.exp(decay*(t-timeToClimb))/w)];
}


Dan

[Sebastian Heinrich]

Hi Dan,
wow, that works perfectly.

Yes, sure, those example values 5px/sec wouldn’t do it.

I am creating a slideshow with hundreds polaroid images. This is so awesome coz it’s completely autmated now.

I wish I was able to come up with such solutions. Would probably take me days. I can only partly understand the code. That’s really bugging me.

Thank you so much.
Sebastian