Inspiring

Answered

Expression to move x-position negative to null?

Forum|Forum|4 years ago
October 11, 2021
3 replies
625 views

Hi there,

How do I make one object to move the opposite way of another?

An example of what I want to achieve: In a 1000x1000 comp with two objects placed in the middle, in one of the objects (or perhaps a main null) I enter +200 on the X-position. Object 1 moves to x-position 700, object 2 moves to x-position 300.

All the best

/Pär

During the hours I have searched for an answer for this I found

Expressions

This topic has been closed for replies.

Correct answer Mylenium

My mistake. I overlooked that it's a vector value and the components need to be addressed. I usually isolate this in the first step, so I missed it. This should work:

[pOut[0],p1[1]]

Mylenium

MyleniumCorrect answer

Legend

My mistake. I overlooked that it's a vector value and the components need to be addressed. I usually isolate this in the first step, so I missed it. This should work:

[pOut[0],p1[1]]

Mylenium

D

DefineyourgoalAuthor

Inspiring

Absolutely fabulous! Thank you both!

Mylenium

Legend

Position data is a 2D or 3D array and needs to be addressed accordingly:

[X,Y]

In your case that translates to

center = [thisComp.width,thisComp.height]/2;
p1 = thisComp.layer("Object 1").position;
pOut=center*2 - p1

[pOut,p1[1]]

Mylenium

D

DefineyourgoalAuthor

Inspiring

Thanks for the input Mylenium!

I tried it but get an error-message saying pOut has an undefined value. Yet that's what you already defined in that expression right? See attached image.

Thanks

/Pär

Dan Ebberts

Community Expert

There are a couple of ways, depending on how you have things set up. In the simplest way, you have to define a reflection point. In this example it will be the center of the comp. You would apply this expression to Object 2's position and it would keep Object 2 on the opposite side of the reflection point from Object 1:

center = [thisComp.width,thisComp.height]/2;
p1 = thisComp.layer("Object 1").position;
center*2 - p1

D

DefineyourgoalAuthor

Inspiring

This is great Dan! Thanks.

How do I keep the Y-position to move the same meanwhile the x-position uses your brilliant expression?

After your expression, I tried to add:

// for horizontal layer
c = thisComp.layer("the layer you want to mirror").position;[value[0],c[1]];

That made your expression to not work anymore 😕😕

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