Any algorithm for "soft folds" [weighted vertex]?


Is there any established algorithm for soft folds when a character folds their arm (or any other body part)?

Also how do you “mark” a vertex for folding in blender?


By the way, I was told quaternions are the best way to store rotations. Is a quaternion a rotation “w” across an axis produced by the vector [x, y, z] such that a quaternion is represented as w+xi+yj+zk where i j k are imaginary values?