How to link X rotation in one layer to X rotation in another?

[Dan Ebberts]

It depends on exactly what you have in mind. If you just want Layer 2’s x rotation to be some multiple (or fraction) of Layer 1’s, it could look like this:

m = effect(“Slider Control”)(“Slider”);
thisComp.layer(“layer 1”).transform.xRotation*m

If you wanted Layer 2’s x rotation to be offset by some fraction of Layer 1’s x rotation change since time zero, it could look like this:

m = effect(“Slider Control”)(“Slider”);
r = thisComp.layer(“layer 1”).transform.xRotation;
value + (r – r.valueAtTime(0))*m

Dan

[Eric Goldstein]

Hi Dan,

Thank you for your help. But, could you elaborate on your answer. I’m new to expressions. Would I place the formula in the “child” layer’s X rotation? Would I place the slider on this same layer? How do I hook the slider into the formula and how do reference the “parent” layer?

Thanks,

Eric

Eric Goldstein
Giraffe Film Company
Los Angeles
eric@giraffefilm.com

[Dan Ebberts]

>Would I place the formula in the “child” layer’s X rotation?

Yes.

>Would I place the slider on this same layer?

Yes.

>How do I hook the slider into the formula?

m = effect(“Slider Control”)(“Slider”);

>how do reference the “parent” layer?

thisComp.layer(“parent layer name goes here”).transform.xRotation

Unless you actually have the two layers parented together, in which case you could just use parent.transform.xRotation, but in that case you probably wouldn’t use this expression anyway.

Dan

[Eric Goldstein]

Hi Dan,

Thank you for your help. I got the expression to work to some extent, but for some reason it rotated the layers I was working with 180 degrees perpendicular to the axis I was working on. And the slider was extremely sensitive making very big movements for small incremental changes. I want to learn more about expressions, but I always run into the problem of time.

In the end, I did it the old fashioned way put the same keyframes from the “parent” layer into the “child.” But, I do want to learn more about expressions.

Thanks again for your help.

Eric

Eric Goldstein
Giraffe Film Company
Los Angeles
eric@giraffefilm.com