[ SkinnedMesh ] Way to find out bone index number which is refered by skinIndex ?

[Duke-2]

Background

• I would like to find out the list of mesh vertices which is bind to 'head' bone.
• The vertices has bone information the as index number in .geometry.attributes.skinIndex.array
• I calculated the index number of the bone as the alphabetical order of humanoid.humanBones 's children nodes
• However, the vertices list seems not correct because it is not axis symmetric

Question

1. Way to find out bone index number which is refered by skinIndex ?
2. Any easier way to get all the vertices bind to 'head' bone?

[ke456-png]

How will it be put to use? VRMFirstPerson might be helpful.