db2ac79fc7
approach does not work very well. Using a cross section estimate still causes large oscillations due to varying hair force based on angles. It also requires a sensible hair thickness value (particle radius) which is difficult to control and visualize at this point. The new model is based purely on per-vertex forces, which seems to be much more stable. It's also somewhat justified by the fact that each hair vertex represents a certain mass. Conflicts: source/blender/physics/intern/BPH_mass_spring.cpp