The bento skeleton I tried for OpenSim 2 years ago was a try in this direction. Meanwhile I am able to use wings or other stuff by appending parts to the make human base mesh. So a lot is possible.
At least for debugging or testing you can always check how I tried to solve it, because the bento has a lot of bones which cannot end in cubes etc.
My tools on github are designed to support the weights later.
Here is the skeleton:
http://www.makehumancommunity.org/content/bento_alpha_1.htmlFor rotation planes or head or tail positions: The references must be resolved internally, yes. Rotation planes can be re-used, so it is not an 1:1 mapping. As you can see from my bento version I renamed everything but also used an own syntax like _t instead of __tail ... because the names are a bit longer anyway for the bento ... wonderful ones like "mHandThumb1Left"
I did a lot with the help of scripts. You can still see that on my github page
https://github.com/black-punkduck/MakeHuman-HelpersE.g. extract_weights was used to extract the weights of the fingers from the .mhw file and renamed it using the transpose file in the data folder. That was all ASCII based to keep some values ... because I did not want to do all weighting again.
but another question:
UE4 is running on my box as well. On my box it works with the normal skeleton but that means to do the animations all from scratch. Since I only tested my characters to figure out if it looks natural, I have more problems when e.g. the character sits (no butt at all
) or when arms are over or behind the head. This is, because UE uses the same standard technique like Blender in standard mode. So "keep volume" is not available. I use that in blender in combination like mindfront did, so most poses I can do in blender but in UE they look "funny".
Therefore I already thought of a skeleton with extra bones to keep the volume. I also think of double knee joints to get rid of the problem of e.g. weird kneeling positions. On the other side: the more bones, the slower the engine. And extra bones are dependent (they use constraints) so I would need to do the animations the same way. For me it is part of the process, I use the retargeter and correct the animations, I also have a tool which is able to put the motion in place (rotation and translation). So in my case the pipeline would always be MakeHuman => Blender => UE, because blender then will create the constraints by script. I learnt UE can use IK ... so may be sth like that could be implemented as well. Maybe the IK bones could already be generated in MakeHuman, but the logic has to be done in Blender then.
But most people use the mannequin-like skeleton (which can be adjusted I learnt a few weeks ago to get rid of the weird arms because of bone length etc.) because they can easily download hundreds of animations for all purposes. Since this skeleton is not as far away from the game skeleton we have, it should be easier to be solved than my idea of more anatomical correctness.