Twist Rig problems in 3ds Max

STEVONATRON

This is a long shot, but I'm hoping someone can help.

I'm using Digital Tutors to learn how to twist a rig - the particular tutorial is called 'Rigging Quadrupeds in 3ds Max'. The element I'm having trouble with is the vertebrae; the set up is a spline skinned with separate bones linked to helpers which are constrained to it. Using Float Expressions, the bones are supposed to twist according to the rotation of the controllers at either end.

But instead of a nice gradual twist between the two ends, the middle bone twists the most, then the two on either side and so-forth. The result is more of a C-shape than an S.

Does anyone know what I'm talking about? I've asked on the DT forums but they're notorious for lack of help.

STEVONATRON

Thanks for the reply Dustinbrown, I neglected to mention that Ive done the tutorial several times over, and followed click by click, word for word.

I think I'll take up on your advice on posting the file on cgtalk. cheers!

Mrfred

check your parenting, then check the value you entered in the expression systems. I'm pretty sure it's something really obvious you neglected to double check because you thought it was too obvious that it couldnt be that issue... BUT IT IS :P

STEVONATRON

Ha, yeah it always is those obvious things that tun out to be the issue, Mrfred. On this occasion it's really not so obvious - I've scrupulously compared my rig with the tutorial source file to find differences, but nothing stands out.

That said, I'm kinda feeling paranoid now... Think I'm going to check again

Mrfred

I'/ve never seen that tutorial but I could take a look at your file if you want.
I work as a rigger so maybe I can find the issue there. who knows...

STEVONATRON

That'd be great Mrfred. How do people normally share files like this? Polycount doesn't seem to accept anything other than image attachments...

Can I email you the file? If so, could you PM your address?

Mrfred

I think there;s a few mistake here and there...
1-Grp_AimNeck_F expression was targetting the head Z axis instead of Y
2- samething with Grp_AimNeck_B
note:You changed your axisorder on both ctrl to be YZX so dont forget to be carefull when picking them in the expression selector
3: now I'm not sure about this one I think I did that by mistake and I overwrote your file so just double check to be sure I didnt do it: Grp_AimNeck_F is using Grp_AimNeck_G Y axis as the head while Grp_AimNeck_B is using the chest Control. Shouldnt Grp_AimNeck_F use the head control as well? or at least HLP_EnvelopeHead?

I sent you the file

STEVONATRON

OMG, you've cracked it. I didn't receive your email with the file, but just followed what you've wrote here - and it works now! Absolutely brilliant, I couldn't be more grateful to you Mrfred. I've spent more than two weeks trying to figure this out and was beginning to get down about the whole thing.

Many thanks again