6dof with plastic deformation

[snegovick]

Hello, i had an idea of building deformable mesh, describing it with several primitives. I didnt want to use softbody because i didnt need this kind of precision and also my meshes are best described with box primitives or such. Thats why i decided to connect several boxes in one plane with 6dofs with springs. Everything was cool except the fact that its behavior didnt have classical elastic/plastic regions. So i decided to override 6DofSpring and add some threshold for displacement. So in my Deformable6DofSpring class there is a check in update springs method, which checks if delta is greater than some threshold displacement and if any of deltas is, then it updates equilibrium point to be actual point at time of calling update springs. Also, i disabled collision detection between parts of my deformable object to prevent instability. I could put my code here if there is any need in it. Or maybe my idea is repeating something, then i would appreciate if anybody would show better way to implement fast deformable meshes with elastic/plastic regions.