“Show hair grid” is of course not necessary for hair dynamics to work, but I like to visualize things in order to see how they work. I find the hair dynamics settings partly a little bit confusing. For example, the influence of the voxel grid size on the hair dynamics calculations (target density) as shown in the video is really significant.
PS: I just tried hair dynamics (with “regrow” checked) in Blender 2.8 with a cube falling onto a plane and the hairs just stayed in the air while the cube was falling. Also hair dynamics and rigid body simulations often make this Blender version crash on my computer when I’m trying to bake it.
