Moho Animation Forum

How do I mask that line, by using the semi-transparent shape as the mask?

https://www.opendrive.com/files?6558847_ZEgxs

I made the shape semi-transparent, to explain what I want to do.
I have created a group, but I am not sure how layer binding works when working inside a group folder.

The idea here is to progressively show the line, as the arm rotates.
It is a simple idea, but I haven't been able to implement it.

Can someone explain to me how to do it?

Thanks,

Rui

The file is the new vers. 7 fomat, so a lot of users might not be able to open it.

After looking at it, I don't think this is the best way to accomplish this. You want the arm crease to appear naturally when the arm bends, right? I'd suggest this popular thread:

arm bending

It's one of the better arm set-ups, imho.

I have tried it it it works beautifully for arms like the one in that thread.
But, in order to be able to get the natural crease effect on any arm, without having to worry abou arm geometry, the masking method would actually be more general-purpose and would free the artist, I think.
I am trying to get as free as possible from bone setups that must be carefully designed with bones, and trying to select methods that will work for any pose.
But I am not looking for the universal rigging, holly grail kind of thing.
I just think that a mask-baseed method would be so easy for artists to understand and not have to tweak arm geometry so that it looks good, etc...
I used to rely on scripts and smart design, but nowadays I try to look for more artist-friendly stuff.
Things like methods that are well defined and relief the artist from the burden of shape trickery.
I may be going in the wrong direction, but I guess what I am really looking for is a series of well established, easy to learn, easy to remember, not-too-much-shape-trickery-centric methods.
But I digress...
Thanks for the answer.
Cheers.

Rui