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acertik
acertik
Inspiring
May 11, 2017
Answered

Advanced expression (position) question

  • May 11, 2017
  • 2 replies
  • 5690 views

I'm usually pretty good with expressions, but I'm really stumped on this one:

For the sake of keeping it simple, let's say I have:

1. A layer

2. A null object with a slider

I want my layer to slide in (x position only) from Point A, to Point B, pause on Point B for a few seconds, then slide back to Point A.

Here's the challenge: I want Point B to be controlled by the slider, but I always want Point A to be the same exact starting/ending point. (say 0, for the sake of simplicity). So the animation should go:

0 to X, then X back to 0, where X is the value driven by the slider.

Hope this makes sense. Thank you in advance to anyone who might be able to help.

This topic has been closed for replies.
Correct answer UQg

Thank you! This is exactly what I needed.

Now, for an added challenge: the scope of the project changed a little, so instead of having the layer move back to its original position (0), now, after pausing on the slider value, it needs to move to a third position, say 50 for example.

So the animation should go:

0 to X, pause, then X to 50. (50 always being constant)

I have admit, I am mostly unfamiliar with what you came up with in your expression. Thanks again for your help!


You need slight modification (the thing called C replaces A at the very end):

t0 = inPoint; 
transitionDur = 3; 
holdDur = 5; 
// A, B : start/end value for the x coordinate 
A = valueAtTime(0)[0];    // or some constant numeric value like 0 
B = thisComp.layer("Null 1").effect("Slider Control")(1).value;
C = 50;
y = value[1];                // or some constant numeric value like 0 
t1 = t0+transitionDur; 
t2 = t1+holdDur; 
t3 = t2+transitionDur; 
x = (time<=t1) ? linear(time, t0, t1, A, B) : linear(time, t2, t3, B, C); 
[x,y];

@foughtthelaw : You need to enable the "Advanced Editor", then >>(insert)>(SyntaxHighlightning)>javascript

Xavier

2 replies

S
sreej50928509
Participant
April 4, 2020

Hi, I have a basic rectangular shape with text sliding from left to middle of the screen (x1  to x2), and when it reach it give a shake (Wiggle effect). I have key framed the wiggle effect to do that. I have created null and created controls for color and other parameters. But I don't know how to create a control for the wiggle effect only for the particular period I keyframed for. Played all day .. No luck. Please help me to solve this.

See the file here . https://drive.google.com/open?id=1g1hsfh9clb3ssXCEpIIZ7ci2b5iyjLwS

R
Community Expert
Rick GerardCommunity Expert
Community Expert
April 4, 2020

I just answered this same kind of question in another thread. You can use the inPoint and outPoint of another layer in an if-else statement to turn something on or off. Check out this example:

 

ctrl = thisComp.layer("Null 1");
amp = effect("Slider Control")("Slider");
if (time < ctrl.inPoint)
	wiggle(6, amp)
else if (time > ctrl.outPoint)
	wiggle (10, amp)
else value

 

This expression is defining ctrl as a layer named "Null 1" in the first line. It is looking for a slider control on the same layer and calling that variable a. The if statement says if the time is less than the in point of ctrl (Null 1) then wiggle 6 times a second whatever the value in the slider is but if the time is greater than the out point of Null 1, wiggle 10 times a second whatever the value of the slider is, but in between the in and out point of the ctrl layer (else) just use the value of this property even if it has keyframes. It's pretty straight forward. 

 

foughtthelaw
foughtthelaw
Inspiring
May 12, 2017

keyframe your A and B position and try this on your position value

s = LINK ME TO YOUR SLIDER CONTROL EFFECT;

valueAtTime(linear(s,0,numKeys,key(1).time,key(numKeys).time))

The slider will now blend between the 2 positions

acertik
acertikAuthor
Inspiring
May 12, 2017

Thank you for your help.

Unfortunately, this didn't quite work. Now my layer x position stays at 0 throughout, no matter what the slider value. Any other ideas?

Thanks again.

UQg
UQgCorrect answer
Legend
May 12, 2017

Thank you! This is exactly what I needed.

Now, for an added challenge: the scope of the project changed a little, so instead of having the layer move back to its original position (0), now, after pausing on the slider value, it needs to move to a third position, say 50 for example.

So the animation should go:

0 to X, pause, then X to 50. (50 always being constant)

I have admit, I am mostly unfamiliar with what you came up with in your expression. Thanks again for your help!


You need slight modification (the thing called C replaces A at the very end):

t0 = inPoint; 
transitionDur = 3; 
holdDur = 5; 
// A, B : start/end value for the x coordinate 
A = valueAtTime(0)[0];    // or some constant numeric value like 0 
B = thisComp.layer("Null 1").effect("Slider Control")(1).value;
C = 50;
y = value[1];                // or some constant numeric value like 0 
t1 = t0+transitionDur; 
t2 = t1+holdDur; 
t3 = t2+transitionDur; 
x = (time<=t1) ? linear(time, t0, t1, A, B) : linear(time, t2, t3, B, C); 
[x,y];

@foughtthelaw : You need to enable the "Advanced Editor", then >>(insert)>(SyntaxHighlightning)>javascript

Xavier

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