at begin of humanoid traversal:

- reset skinCoords to initial

at each traversal of each joint:

- accumulate skinCoords updates by
- adding on current skinCoord the
- weighted difference between
- the transformed coord and the
  original, initial coord

The transformation is the global joint transformation adjusted to be relative to the global humanoid trafo by multiplying with inverse.

at end of humanoid traversal, after children traversal:

- force update of skinCoord users.

TODO

- skinNormals
- reuse MFVec3f at resetting
- reduce updates