I remember reading something on blendernation a while back about trying to incorporate some kind of muscle system into blender (so that when an arm contracts, it’ll cause a bulge in the bicep for example).
Anyone know what happened to that? 
Check this site out:
http://www.jpbouza.com.ar/ESP2/descargas/blenrig-3/id/en
The guy has developed a muscle system for blender.
Hmm… is that really a sort of general purpose muscle system? I’m not making a human character, I’m making a weird alien/reptilian monster with 6 limbs… not exactly humanoid looking.
Generating realistic skin deformations arising from joint movement and muscle contraction is a requirement for producing realistic human character animation. For example, the human arm, hand, or foot change shape in significant ways during motion, ways which are difficult to model accurately with traditional character animation techniques.
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