[Bf-committers] Durian/Hair Troubles

Campbell Barton ideasman42 at gmail.com
Thu May 13 15:45:48 CEST 2010


Over the past weeks we have been attempting to get hair working for
all our shots.

So far Joe has been working on changes to the solver code in our own
branch but the results solve some problems while causing others (Im
not sure on the details).
Joe says the problem is the goal code, which is a little hackish, and
the bending springs don't work right for hair.
so it would be a real help is dev's who are familiar with these
problems can investigate.

I haven't been involved in the hair solver side of things, mostly just
making sure its possible to run the simulations on proxies on our
linking setup, testing and setting up bakes for our shots, have cache
save/load etc.

At the moment it would even be good to see a mediocre hair sim even if
their are intersections with the head.
>From tweaking the settings I had trouble even getting this, though its
possible that the problem with my settings.

Would greatly appreciated if any developers have time to look into this.

Notes:
- can test in trunk or render branch, give different results but
neither are great.
- collision is off in this file, seems very tricky to have working
stable, (sintel's low poly head mesh is a collier).
- try run the bake on 2-3 sec for fast updates (Brecht has done some
work on realtime redraw's but not ready to commit)

Heres a blend file with Sintel's hair and the animation (1.0mb)
 http://durian.blender.org/wp-content/uploads/05.8b.blend

Heres a video of what I managed to get so far (2.0mb)...
 http://durian.blender.org/wp-content/uploads/05.8b.ogv

Here are the settings used in the animation...
    psys.cloth.settings.quality = 30
    psys.cloth.settings.structural_stiffness= 12.0 # good overall
value to control stiffness, 12 is needed for running up stairs
    psys.cloth.settings.pin_stiffness = 0.5 # above 0.6 can become unstable!
    psys.cloth.settings.bending_stiffness = 80.0
    psys.cloth.settings.spring_damping = 30.0
    psys.cloth.settings.air_damping = 2.5
    psys.cloth.settings.mass = 0.015
    psys.cloth.settings.internal_friction = 0.1 # 0.9 makes hair too symmetrical
    psys.cloth.settings.structural_stiffness= 60.0

-- 
- Campbell


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