I could never understand animation groups well enough to implement this, though I’d love too and actually was considering trying it again this week. There was a thread about this problem before: How to find the total number of frames of a skeleton animation?
From what I remember at the time, it seems that it’d require some manipulation of the RuntimeAnimation class to be able to set a specific frame and capture the transformations. I was a bit busy back then and I couldn’t work it out how that would work. I’ll try to look at it this week again (no promises!), and of course help is always appreciated.
Besides the basic problems of manipulating the AG directly to bake things, I remember there were two other minor issues to handle everything one would need. All this comes from what my memory is of the analysis I did back then, so this might all be way off.
First one was that applying VATs might clash with animation groups, but I think this was easy to handle by not using the AGs and VATs at the same time.
The second issue is that the VAT implementation does not handle composition of animations IIRC. So if you want to play and stop multiple groups it won’t work. My memory is fuzzy about this, but I think it’d be possible to use multiple textures (but not arbitrarily many), or do a small patch to the VAT so that it’d compose transformations if you had more than one applied (but I think it was not trivial since the order of transformations matters).