TLDR version: if you’re building animation or rigging tools for Maya, and you’re interested in ways how people setup rigs to map their left and right joints, here’s a summary of various ways spotted in the wild.
One thing I wanted to fix for quite a while in ngSkinTools is how left side influences are matched to corresponding right side influences and vice versa. Standard Maya weight mirroring tools simply match by joint position, so I felt pretty good about also giving the option to match by name: if you have L_clavicle and R_clavicle, you just say “I’m using L_, R_ as prefixes”, ngSkinTools drops these prefixes and finds two joints named as “clavicle”.
A bit later an option to match by suffixes was also added, because some people like clavicle_L better than L_clavicle. And only recently I discovered that there’s also naming schemes like leg_L0_3_jnt (looking at you, mGear!).
This all is enough to get this itch that relying on a naming convention is not the most reliable thing one would end up doing. I mobilized my Twitter swarm of field professionals asking what they do about this topic, and below is what came out of this (you can also see the full thread here).
Naming convention
Coming up with a special name structure seems to be most prevalent, probably driven by the fact that you have to rename those joint01, joint02 anyway.
Suffixes (_L, _l, _lf, _R, _r, _rt) or prefixes (L_, R_, lf_, rt_) seem to be most common, but middle of the name isn’t that rare (leg_L0_3_jnt, arm_L_01_bnd) as well.
In rare cases, “center” gets it’s own prefix (C_) - could be a great way to distinguish between center and asymmetric (only present on one side of the rig) joints.
As a slight variation of naming convention, namespace could be used: L_arm:_upper_1_JNT. The person that gave this example said this is done to make renaming of modules easier (an prefix is a part of module name).
Joint labeling
In joint’s “Attribute editor” UI you can find a “Joint labeling” section where you can specify joint side, but most importantly, setting “Type” to “Other”, you can specify a custom label:
setAttr "leg_L0_2_jnt.side" 1;
setAttr "leg_L0_2_jnt.type" 18;
setAttr -type "string" leg_L0_2_jnt.otherType "leg_2_jnt";Later pairs can be matched by having same custom label. This isn’t a very universal panacea as you can only do this for joints, but not other parts in your rig.
Attribute connections
So far the most robust option in my opinion to have unambiguous links exactly the way you want. If you don’t trust me, listen to Siew Yi Liang:
Message connections. Relying on naming conventions is a surefire way to increase your support burden with the number of degenerate cases that occur.
So far I’ve seen/heard:
- Each joint has a custom attribute added (e.g. “oppositeJoint”), and a connection is created to that from an opposite joint message attribute, e.g.:
L_joint.message -> R_joint.oppositeJoint; - “Hub” nodes providing links to left and right joints.
Metadata
- Custom string attributes stating the name of the opposite joint (slight twist on message attribute)
- JSON/XML metadata on a central location (scene, rig root) - a twist on hub nodes with message connections.
Summary
I intend to expand the list as I find more examples. Let me know if you’ve come up with other creative ways or variations of the above!