Influence Wrapping in Maya…


On yet another rabbit trail of problem solving on Morpheus 2.0, I came across an issue where wrap deformers weren’t working as needed. Namely transferring blendshapes¬†from one mesh to another when the shape of the target mesh wasn’t like the original. Even geo changes in regions no where near the ‘to bake’ geo were¬†affecting it.

So did some googling and came across a concept I’d not used before – namely using a mesh to deform another with a skinCluster.

Neat, so how do we do it?

  1. Get your target and source mesh ready
  2. Create a joint and skinCluster your target mesh to it
  3. Add the driving mesh to the skinCluster with the useGeometry flag ( sample code for this line below).
    1. polySmoothness flag. This controls the smoothness of the mesh deformation of the target mesh.
    2. A polySmoothness of 0 is the closest to a standard wrap deformer
    3. In my initial testing I found that this flag could only be set consistently on creation. Editing the flag could push the smoothness up but not down (in 2011 at least).
  4. Make sure the useComponents attribute on the skinCluster is set to True. If you don’t see the deformation doing anything this is the likely culprit.

I wrote a script to set this up but it’s still wip. It’s a function found here: cgm.lib.deformers.influenceWrapObject. Because of the issue noted in step 3.2, I added the polySmoothness as a creation flag.

This method of wrapping is much more localized than wrap deformers when the mesh isn’t close AND provides an easy way to paint weights for the deformation.

Acknowledgements:

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