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CAT and arm twist bones
show user profile  suraka

Hi, we've been using CAT for a few years now and I was wondering if anyone has a general solution for this issue.

What I mean is the segment closer to the collarbone should keep it's Z(?) rotation and the second one should rotate half of it. You know, usual twist bone behavior. Applies to legs as well.

We've been taking different approaches, from our own twist bones to manually animating when needed. I know the right approach is using muscles but we are avoiding them as we think it's an overkill when we can just use this and it works alright (or should).

Running Max 2014.

Thank you.
read 601 times
1/21/2015 5:24:04 PM (last edit: 1/21/2015 5:24:04 PM)
show user profile  Mr_Stabby
You're using the regular ik controller with cat bones I presume. The cat arm/leg rigs have a built-in IK system where the hand works as ik target and the elbow as swivel node. The hand/elbow also work as upnode for the upper arm/forearm twist which is controlled by the twist weight curve throughout the arm.

Its a bit different way of animating but comes down to same amount of clicks, also is fully compatible with the cat animation manager.

Additionally I think there is an option to create CAT ik target in the hand (make sure to set the bar to full IK) which works like regular HI IK but instead of a swivel node it uses the bone rotation. Might be closer to what you're used to, havent used it in a while so don't remember.

read 597 times
1/21/2015 6:16:21 PM (last edit: 1/21/2015 6:20:15 PM)
show user profile  suraka
No, it's actually CAT's IK system, it's a regular CAT arm. I used IK because to show it but it actually happens with FK also.
When twisting the collarbone, the 1st twist bone should follow the collarbone and the 3rd should stick to the elbow.

Tahnk you
read 593 times
1/21/2015 6:39:58 PM (last edit: 1/21/2015 6:39:58 PM)
show user profile  herfst1
What about orientation constraints? Say you have 3 bones in the forearm you can orientate the one closest to the wrist at 66.4% aligned to a dummy (that's aligned to the wrist bone( and 33.3% aligned to another dummy (which is aligned to the elbow). Have a 50% ratio orientation for the middle bone. Lastly for the bone closest to the elbow you align it the inverse of the wrist orientation (if you know what I mean).

Rigging is hard to describe in words.

[edit] P.S. You might need to set up look at constraints for each bone as well. Actually, if you do that you can also select upnodes, which is handy. You can make helpers above the forearm that use position constraints between the dummy at the elbow and the dummy at the wrist (using the ratios I gave earlier).
read 587 times
1/21/2015 7:04:37 PM (last edit: 1/21/2015 7:08:16 PM)
show user profile  suraka
herfst1: that's what I was trying to say when we used our own twists bones, the traditional max bones and max animation controllers way. I'm looking for a way for CAT to do it native. Just as the forearm does it.
read 581 times
1/21/2015 7:12:51 PM (last edit: 1/21/2015 7:12:51 PM)
show user profile  herfst1
Ah, okay. No, can't help you then, haven't seen that option.
read 579 times
1/21/2015 7:16:14 PM (last edit: 1/21/2015 7:16:14 PM)
show user profile  Dave
I've never used up-nodes on the elbows before, but sure enough... same issue. Bit strange really.

I can't help.

"I flew over Egypt once"

read 576 times
1/21/2015 7:28:15 PM (last edit: 1/21/2015 7:28:15 PM)
show user profile  Mr_Stabby
>>When twisting the collarbone, the 1st twist bone should follow the collarbone

yea cat doesn't do that but to be fair, neither do humans (you cant really twist your collar bone). If you want that you're going to have to build a custom rig

read 566 times
1/21/2015 8:50:01 PM (last edit: 1/21/2015 8:50:01 PM)
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