Maya 2016.5 adds built-in shape inversion, so this plugin is no longer needed.

This Maya plug-in allows creating inverted blend shapes that can be sculpted in-place, like Maya 2016's blend shape sculpting.

This is based on Chad Vernon's cvShapeInverter: https://github.com/chadmv/cvshapeinverter

Install by copying zInvertedBlendShape.mod into Maya's modules directory and setting the correct path, and adding this to your userSetup.mel:

source "zInvertedBlendShapeMenu.mel";

An "Inverted Blend Shape" menu will be added to the Deform menu in the Rigging menu set.

To create an inverted blend shape, first create a front-of-chain blend shape deformer on your mesh. Select your mesh, and select Inverted Blend Shape > Deform. This will create an inverted shape and hook it up to the front-of-chain blend shape deformer. To sculpt the blend shape, select the new shape and select Enable editing. This command works like selecting "edit" in the blend shape dialog. Be sure that the output mesh is selected when sculpting. The blend shape node can remain hidden.

If you change the character's pose while editing, the blend shape will continue to work. However, if you want to make further changes after changing the pose, you need to tell the deformer about this by selecting Update pose. If you're editing the shape and vertices are moving in the wrong direction, you probably need to do this.

You can delete history on the blend shape mesh to remove the inversion node, which will bake the inversion to the mesh. This can be done if you don't want your scene to require this plugin to be available.

To recreate the inversion node to make further edits, or to edit an existing inverted blend shape, select the blend shape mesh and select Add deformer.

You can also simply delete the whole blend shape when you're done, and the blend shape will be baked into the blend shape deformer as deltas.