[Ben Jaffe]

Oh okay, that makes a lot of sense. Is there a way to get its final position post-expression? I know there’s code to get the real rotation of an object that has auto-orient turned on. Anything like that for position that you have seen?

And thank you so much for your help!

[Ben Jaffe]

Darby and Dan, thanks for the responses.

I may do what you suggested Dan, but it will be a long comp, and will definitely be very bogged down.

But ultimately, there is no way for the object to use its position from the previous frame that either of you know of? No workarounds with other nulls or sliders… Is it the fact that it’s a loop which is causing the problems?

[Ben Jaffe]

Hi Dan,
Thank you for your response. That would work, but my example in the post is a simplified version of what I’m doing. I am actually figuring out formulae for a bike wheel trailing a null object which drags around the front wheel of the bike. The idea is that I just drag around this null object, and the bike takes care of it’s own orientation, among other things. I figured trying to explain and post the whole thing would be overwhelming for the forums, so I made a simple example that would get across the basic concept I need help with.

Can you think of a way to use the values from the previous frame in the expression? There’s gotta be a way. If there isn’t, it seriously limits what I can use expressions for, and it means a lot more toiling over keyframes that should be able to figure themselves out.

Ben

[Ben Jaffe]

To preface, I’m also new to expressions, but I think I can help, so here it goes:

1 – why not get a random value for x, then set y to x’s value? That way you’d get a random value for x and y, but they would be linked. ex:
x = Math.random() * (set_X[1]-set_X[0]);
y = x;

2 – to get the position of the layer that the expression is in, use transform.position – you can use the pickwhip for the expression to get any other layer. I assume the wiggler is not an option right? With the wiggler, it won’t be able to wander off, but maybe that’s what you want.

[Ben Jaffe]

That worked perfectly! Thank you so much!

By the way, to get the speed, I’m using
comp(“Final Animation”).layer(“cyclist1”).transform.position.speed

and it works! I’ll post the final formula I use for the bike wheel when I finish it.

Thanks again for the help!

[Ben Jaffe]

Hi Timothy,
To disable OS X’s F- shortcuts, go to System Preferences – “Keyboard & Mouse,” then click on the “Keyboard Shortcuts” tab. The F- shortcuts are near the bottom of the list, and you can simply uncheck them. You may also want to run down the whole list, in case other functions got mapped to other F keys.

-Ben