1ed88bb24e
This implements a penalty force as well as a repulsion force to avoid further penetration, as suggested in "Simulating Complex Hair with Robust Collision Handling" (http://graphics.snu.ac.kr/publications/2005-choe-HairSim/Choe_2005_SCA.pdf) Friction forces are still missing. More problematic is handling of moving colliders, when face swap places with the hair vertex and a collision is missed, putting the vertex inside the mesh volume. Larger margins might help, but ultimately using Bullet collision detection is probably more reliable and failsafe.