Lukas Tönne
7a7778d003
These are much better suited for creating stiff hair. The previous bending springs are based on "push" type spring along the hypothenuse of 3 hair vertices. This sort of spring requires a very large force in the direction of the spring for any angular effect, and is still unstable in the equilibrium. The new bending spring model is based on "target" vectors defined in a local hair frame, which generates a force perpendicular to the hair segment. For further details see "Artistic Simulation of Curly Hair" (Pixar technical memo #12-03a) or "A Mass Spring Model for Hair Simulation" (Selle, Lentine, Fedkiw 2008) Currently the implementation uses a single root frame that is not yet propagated along the hair, so the resulting rest shape is not very natural. Also damping and derivatives are still missing.