Game Rig Wrist Twist

Hello BlenderArtists, I have for the past while been working on a game rig, and as someone whos more acclimated to rigging in Maya have had some difficulties adjusting to Blenders way of doing things. In particular I am wondering what would be the best approach to incorporating a single bone wrist twist that deforms in a believable way, some of the methods I have tried haven’t really worked out and most research into the matter comes up with answers involving Rigify, which doesn’t work for me as this rig is scratch built.

any answers are much appreciated.:yes:

For automatic twist of the hand wrist according to hand rotation, the following works for me:



The extra bone (lower arm twist control) is parented to the hand bone (with offset) and has a damped track constraint, pointing to the empty (which is parented to the upper arm bone) at the elbow joint.
This way the lower arm twist control bone rotates in local y along with the hand bone, but if desired can be manually animated to correct unwanted distortion…

This should also work if you prefer to CopyRotation-constrain the hand bone to the IK control.

Of course the wrist area of the arm geometry must be weight painted to the twist control bone with smooth transitions.

Another way would be segmenting the bones in the Bone Menu / Deform section. This smooths the twisting in local y, but also in the other directions which might give the impression of rubber hose joints and bones.

Hope that works for you

It’s awhile since I have been up on the forums …
so since this is the first post I have seen from you I’m going to assume your not failure with B-Bones…

B-Bones is the way to go in blender with using as few bones as possible to rig a wrist twist…

plus if your looking to get familiar with Character Rigging in Blender (building your own Riggs) I highly recommend Nathan Vegdahls
“Humane Rigging series”…
you can find some parts of it here…

… check it out it’s great…

also for some more speciffic B-bone tutorial stuff…
Check out DaveWards youtube channel…
speciffically this video…
https://www.youtube.com/watch?v=S9bHc2SDg3w

B-Bone is just the display option of the rig, which lets you see the segments you set for the bone in the Deform section.

As I said, for the wrist twist problem you can segment the lower arm bone to get a smoother deformation, but segmenting the bone not only segments the rotation in local y axis, but also makes it bending in other directions. With ease in and out you have some control there, but for my taste it doesn’t solve the issue in some cases.
For me the above workaround (see pictures) avoids that downside --> rotation only in local y axis.

@motim

You can segment the bones if you want to… nothing wrong with doing it that way…

but as the original poster requested…

In particular I am wondering what would be the best approach to incorporating a single bone wrist twist that deforms in a believable way,

the poster was asking for a ‘single’ bone wrist twist…

Thus my post with some suggestions on that issue…

also…

segmenting the bone not only segments the rotation in local y axis, but also makes it bending in other directions.

It’s easy enough to set Ease in Ease out to zero…
(goto… Attributes > bone > Deform > Curve Bones > Ease In and Ease Out > set both to zero)
Therefore locking down any bending in any direction other than the y axis ‘twist’ that is desired here…

Having said this… if your having Twist or flipping issues with your wrist deformations…
a second bone is in order to help solve that issue…
but there are many ways to implement this…

but this is not the posters question …