Two Root joints for Game Rig ?

VaPN

Hello,
I am not a TD, but I am the solo animator at my current job and I need to deal with the creating of the rigs for Unity. 
The coder that deals with character skills and integretion is asking for a rig that has two bones that are having the same hierarchy level -> two roots in the same rig. 
I am using Advanced Skeleton tool for rigging and the issue is that Root_M is the main bone that everything else go under it, including the Chest bone. The idea is when rotating Root_M to not influence the Chest bone. I can do that by switching the Chest to global space in Maya, but aperently Unity doesnt recognize local and global space and the coder insist for the Chest to be at the same level of hierachy as the Root_M or a bone that control the Chest, but isnt influence by the Root_M.
Is that even possible? I am in cosntant battle with the coder about that issue and already getting desperate.

Any tip is welcome how I can solve the issue.  

Ghogiel

Correct me if I'm wrong, but I don't think you can have 2 root bones on one rig in unity, that doesn't really make sense to me. A character can have 2 root bones, via having 2 rigs. Another thing I've seen is 1 root and 2 hip bones. Only seen either of those done with mostly ik based animations so the state machines didn't need to do a lot communicating. 

Anyway, sounds like you are making a mech with independent torso twist or something like that. If it's just about being able to rotate the chest bone independently to the root, I imagine there is an easier way to control locking the torso to a world space direction, eg using unitys aim or look at constraint on the torso bone, the target objects transform could be set and held/updated with some code, then the torso is just going to update it's own rotation transforms via pointing to where ever it's target is regardless of what the root is doing. The torso direction is only updated when you move the target.

poopipe

you can't have two roots to a tree - that's just silly and i expect its actually a misunderstanding

the programmer needs to control part of the skeleton in code - that means they need to be able to find the root of that section - there are many ways to achieve this and they have chosen one (arguably the easiest is by an attribute on a bone but whatever - i didn't write the system)

what i would personally do is  use two proxy rigs (chest and not chest)- these are simple bones that the mesh is skinned to and are what you actually export.
The proxy rig is driven by the animation/control rig (using whichever controllers make sense in maya - haven't rigged in it for ages)  so that animators can animate it without worrying about the wierd hierarchy of the proxy rigs

everyone gets what they want that way - you are also able to change the topology of the export rig without losing animation work


this sort of thing is pretty standard practice - its the same principle as running separate ik and fk rigs - you're just adding another layer