Chris and I have experimented with several approaches of modeling soft bodies in flash (heavily inspired by loco roco ;-)). This is not a priority for the physics engine, but anyway nice to see :-) We have figured out 3 basic ways to do this:
- a spring-mass system with structural springs (e.g. every vertex is connected with every other vertex)
- a spring-mass system without structural springs (hull only) and a pressure force.
- a network of constrained particles using verlet integration.
We have put the third option to code. The downside is that verlet integration requires a tiny integration timestep and many iterations to make things stable so this is a serious performance killer. Things get worse if two soft bodies collide with each other. There is also a rare possibility to break constraints if you push the blob too hard. Option (1) and (2) should be faster to compute, but also less stable.