Hi llorens
Yes, for bear mus-fat sim was done simultaneously in one solver.
mus+Fat coupling is a technique I use all the time, suffice to say it's one of my favorite workflows. I feel that it's always a good thing to have different techniques under your belt.
My reasons for mus+fat coupling:
- Fewer number of sim passes to do.
- Self penetration issues in sim object are taken care of, most of the time.
- And the most important thing I liked is bi-directional pull/push between muscles and fat object and solvers parameters. Mimicking the real-life process.
Unlike in a separate layered approach which is very linear and each driver objects dominates deformation
Mus+fat coupling method does take more time to sim. But one should be able to optimize the setup by fine-tuning e parameters ( Tet resolution, Collision point spacing, sub steps etc...)
Here is post where @jamesj has explained in detail regarding the speed simulation and parameters.
https://community.zivadynamics.com/d/388-simulations-steb-by-steb/4
I often switch between these two method a lot while creating and testing my Sim Setup.
a. Using regular separate layer method, First complete the muscle setup, test with all possible range of motion for extreme poses. Bake muscle abc and use that as zBone to drive Fat zTissue. Once happy with the output. Save the fat zivaVfx file. And in Muscle setup add fat object and by using zBuilder, build only Fat object by transfering its attachment, ztissue and material. And use this final mus+fat setup for my production shots.
Here is the post which explain in detail.
https://community.zivadynamics.com/d/703-zbuilder-transfer-from-file
b. In the case of bear, while building the setup and testing it I worked on a half part ex: left side muscle and fat and once I was happy with the overall deformation just mirrored it. Working on half part cut down ur sim time more or less by 50% so u can test and do more tweaks on parameters and sim iteration.
Hope this will be helpful
rgds
Chris