Hi Misadventure, I am planning to use this method in the new version of my rig, BlenRig.
The previous version of BlenRig had a kind of muscle approximation by using Lattices (you can check it out here)
I´ve done some tests, and for what I can see, in some cases the ShrinkWrap modifier is too precise, specially when you move the character out of its rest position. In some situations, for example a twisting arm, there is a certain degree of movement from where the modifier starts to mess up due to its precision. For example, it starts to do things like moving only one vertex apart from all the other ones. It would be great if there was a parameter that made the modifier behave more like a force field.
Anyway, I´m still planning to implement this in my rig, here´s the thread where I´m posting my progress.
I think this was tried once, with decent results… can’t member where or when, though, just soudns familiar…anyway, real muscles would push blender up 3 or 4 notches, but blender is mostly used by hobbyists, like myself. Many folks wouldn’t find the patience or excitement in learning them. I’d still like them though
hehe wow!! No I´m really busy editing a feature film right now, I think I´ll start working on BlenRig 2.5 again on February.
But for what I tested, using shrinkwrap is perfectly possible for simulating bones deformation, you know, at the knee, the elbows, maybe even the rigs of the torso. No problem with that.
The only problem I found is when you want to do muscle bulging in a twisting area. When the model is not twisting everything works fine, but when twisting occurs everything messes up. A possible solution would be to assign the same twisting deformation to the muscle object, that way, both, the model and the muscle would twist together and their deformation would be even, maybe that could work.
I´ll try that one when I go back to working on BlenRig, if I have time I could do some more tests in January.