Shape Animation Tool
This tool allow to make deformation on any animated geometry after all history. Can using for correcting silhouettes, shapes of animated characters. Can to fix geometry bugs, creases in cloth, or to make more beutyfull shapes when current rig is not enouth.
Usually using on chracters with almost final animation. Can to work on any type of deformed meshes with skin, deformers, dynamic.
This tool using free plugin ShapesBrush for easy sculpting, http://www.braverabbit.com/shapesbrush/
And you need to install it too.
After making corrections in scene not remain any custom nodes. All will be worked in clear Maya any version, becouse using standart blendshapes in worldspace. Interface using PySide, it integrated in Maya from 2014 version.
This tool using simple method. After all history om geometry creating blendshape node and pair targets on every key. Not usind delta, not finding any intermediate shapes, only final geometry.
When tool making shape key, then creating pair of target blendhapes, copy of current final geometry, and add to blendshape node. First target - zero shape, this actual copy of geometry in current frame. Second target - corrective shape, this also copy of current geometry, antill we not starting sculpt this. Zero target make connect from corrective target multiply by -1, so zero target is have negative value from corrective value. This needed for extract difference from corrective shape and original mesh and applying correct deformation after history and not overriding it.
When we start sculpting in some shape key, targets update from current frame, original geometry hidding but corrective shape recreating and this we editting.
After editting mesh and exit from scuplt mode, corrective shape delete and original geometry unhide. It have updated blendshape target. For user this transition fully invisible.
Of course Its all can be make manually, but it to complex for editting on many keys. Also if you change animation after edittind shape, and wish to edit this, you have to remove all corrective and making this from start.
But flex tool even after changing animation of the character allow continue make correctives and all target will be automatic updated.
Custom deformation sample
In this video you can see process making custom deformations on simple box without any rigs.
You can download it from CreativeCrash: