How to get along with 1 weight for 6 DOF


As far as I get “skinning” there’s in a skin section

(At most) one weight per vertex per joint.

That implies that influence is the same regardless of the kind of transformation.

What happens if there’s stretching or compression of “skin”(e.g. “muscle”)-tissue involved and that effect is not symmetrical?

I understand there’s a concept of “constraints” and “stiffness” in the physics module, so it might (just guessing) be possible to

  • first multiply the number of joints accordingly (factor 2-6)
  • then reducing the DOF down to (e.g.) one per joint by such constraints
  • then assigning the desired weights in a skin section

So e.g. a humanoid armature of formerly e.g.

  • 80 bones with 6 DOF each
    would be transformed to a mesh with
  • 480 bones with 1 DOF each.

My Questions:

  • Is there a - likely easier - way to express such complex morphs with <skin> semantics only?
  • Would the constraint-based approach be valid?
  • Is there another constraint based approach?



COLLADA might be able to respresent what you are describing through a combinatorial usage of skin and morph controllers. I.e. the source of a skin can be a morph… recursively. Probably the best examples of morph usage in COLLADA documents is by DAZ 3D.