'roll bones' and other special rig tricks

[timberoz]

'Roll Bone' is a term I am hearing frequently around the game industry and am a bit curious about learning more about it. From what I understand it is a special bone you place within your standard character rig to aid in animation (prevent mesh tearing/etc).

Is anyone here familiar with this term and have used these in game production? Can anyone point to good URL's covering this topic? Anyone here know of any other special character rig tricks to aid in animation in repect to game production (rigid/rigid weighted meshes)

thanks a bunch!

[bentllama]

I am (currently) a games animator and we use "twist bones" in our setups...primarily they are used to allow natural looking deformation of the mesh at points of high torsion...

...usually they are used in the arm to emulate the radius and ulna action (I use them in the bicep area to accomodate for shoulder movement as well)... setDrivenKey is used to split the X rotation between the two (usually a 60/40 split) and the mesh pointweighting is shared between the joints... I then use a "dummy" IK arm rig to drive the arm with the twist joints...

...if all this seems a little confusing I can send you a Maya file example... tell me what version of Maya you are running in an email to:

bentllama@bentllama.com

Later...

In reply to:
'Roll Bone' is a term I am hearing frequently around the game industry and am a bit curious about learning more about it. From what I understand it is a special bone you place within your standard character rig to aid in animation (prevent mesh tearing/etc).

Is anyone here familiar with this term and have used these in game production? Can anyone point to good URL's covering this topic? Anyone here know of any other special character rig tricks to aid in animation in repect to game production (rigid/rigid weighted meshes)

thanks a bunch!

...you were bent...

www.bentllama.com

[zza]

Hi,
Yep, Roll Bones are also used in packages such as Filmbox, to tweak motioncaptue and emulate Ulna/wrist actions. It does help to prevent unsightly twists that can sometimes occur.

You can achieve it by basically splitting the one bone into two bones along an axis. (there are plugins to split bones precisely along an axis)

Take the Elbow Joint for example:
One bone will twist a slightly different amount from the next, giving less twist near the elbow, but more by the wrist.
It can be setup using expressions, driven keys or just by doing it by hand.

In reply to:
'Roll Bone' is a term I am hearing frequently around the game industry and am a bit curious about learning more about it. From what I understand it is a special bone you place within your standard character rig to aid in animation (prevent mesh tearing/etc).