I am using the Default skeleton, and looking at the shoulders and hips, I see more bones than humans actually have. Additionally, shoulder joints are not at a place where the ball joints actually are. Instead, two "diagonal" bones "shoulder01" and "upperarm01" connect "clavicle" and "upperarm02".
I understand that the additional bones are inserted to get better deformations with just weights, instead of needing to use pose-dependend shape keys (joint correction morphs), so I would like to keep using this skeleton, instead of using a simpler one.
The default pose has somewhat angled arms and legs, and I am fighting with rotating them back to a normal standing pose, with nearly closed legs, and hanging arms. Using Blender, I can rotate all bones just fine, but my problem is that I don't know which of the bones need which rotation to accurately simulate rotation around the actual ball joints (e.g. for animations).
Inspecting some community-provided poses in Blender show many different values, some looking acceptable, some looking weird, but none of them looking correct. My own attempts don't look good either.
I currently use these values for a hanging arm, but using these to interpolate a move from the default pose look wrong.
clavicle Z = 0.05
shoulder01 Z = 0.1
shoulder01 X = -0.1
upperarm01 Z = 0.1
upperarm02 Z = 0.1
lowerarm01 X = -0.2
So my question is, if there is any "formula" to transform the (single) arm/leg angle (front view) to the (multiple) armature bone angles in WXYZ?