Keeping linked scale positive

[Xavier Gomez]

To get only positive values, you can do:
x = (your expression);
(x>0) ? x : 0; // equivalent to Math.max(x,0)

For the other part, one way is to name your first layer “LEADER”, the last in the stack: “TAIL”, add 2 nulls, one called “Lead ctrls” and the other “Tail ctrls”, then paste this expression to every item’s scale in the stack

leader = thisComp.layer(“LEADER”); leadctrls = thisComp.layer(“Lead ctrls”);
tail = thisComp.layer(“TAIL”); tailctrls = thisComp.layer(“Tail ctrls”);
linear(index, leader.index, tail.index, leadctrls.scale, tailctrls.scale);

Then adjust the 2 nulls scales. It works the same way with other transform properties.

Xavier.

[Ben Robinson]

Thanks very much for your help / reply. Haven’t had a chance to plug in your expressions yet–will let you know when I do.

Thanks again.

[Ben Robinson]

Hi,

Applying the expression as you’ve suggested…

x=comp(“Comp Name”).layer(“Layer Name”).transform.scale-index;
(x>0) ? x : 0

…returns the following error:

Expression result must be of dimension 2, not 1. Am I missing something?

Also, I’ve just noticed that even the straightforward linking expression

comp(“Comp Name”).layer(“Layer Name”).transform.scale-index

is only affecting the width value; i.e. the index value is only subtracted from the width, not width and height. Why might that be?

[Xavier Gomez]

I suppose you havent copied your expression properly in your first post and apparently you repeated it in your project.

Scale is a 2D (or 3D) array, index is a number. So your original expression would have been
comp("Comp Name").layer("Layer Name").transform.scale-index*something where ‘something’ is something only you can know what it was, but for sure an array of numbers. Probably [1,1].

Xavier

[Ben Robinson]

Hi Xavier,

I see what you mean about the array. It was my impression that an operation on an array automatically affect all elements of the array, unless otherwise separated. Obviously not.

I’m still confused about the only positive value expression. i think I did enter my original expression incorrectly in the first post, where I had, “…layer(“2nd Comp Name”)…” rather than, “…layer(“Layer Name”)…” So should my expression look like this:

x=comp(“Comp Name”).layer(“Layer Name”).transform.scale-index*[1,1]
(x>0) ? x : 0;

Other than including the array multiplier, that is what I input and got the previously mentioned error.

Thanks for your help here.

Ben

[Xavier Gomez]

hmm i’m really sorry. I was mostly answering the second question and didnt pay enough attention to the first one. This one is hopefully working better.

s=comp(“Comp Name”).layer(“Layer Name”).transform.scale-index*[1,1];
[Math.max(s[0],0), Math.max(s[1],0)];

Xavier.

[Ben Robinson]

That works a treat now.

Thanks Xavier.