View Full Version : Bullet and FiberFX... Again

03-25-2013, 03:33 PM
Okay... I'm trying to do something relatively simple. For a test, I've got a character head in layer 1 and fibers (created with FFX in Modeler) in layer 2. I want to make the hair look like the character is falling. With the hair parented to the head, I move head to 100 feet at frame 200. Apply bullet and the hair essentially flies off behind the head. Is there a setting in Bullet that will keep the hair attached to the head?

03-25-2013, 04:15 PM
I'm not sure if I get it correctly but I guess you need to do this:
-open up the Item Properties panel under Bullet on the FX Tools tab
-Select your FFX guides on the right side
-On the shape tab make sure Mesh Filter is set to the weight of the FFX guides, it is some: someobjectname_weight
-set Mass distribution to vertices as well
-also make sure on the obkect properties panel under Deform tab you have an active morph mixe under displacement, you dont need to change anything
inside morph mixer, it is setup automatically

03-25-2013, 05:16 PM
There are a few things you can do:

1. Easiest: Use Edit Guides with Polygonize Fixed instead--this mode works with Bullet without binding because the guides are physically fixed to the mesh.

2. Second easiest: If you have to use externally modeled guides, parent the hair to the head bone. This is what I do for Sister in 'Brudders 2'. Downside is that the roots won't defom with the mesh, if that matters. (In Sister's case, it does not.)

3. Weight the hair properly and use bones like with any other mesh. This will deform properly but if you use subpatches and you go higher than After Morph for Subdivision order, then the wig will not deform accurately. For most human head hair, this may not matter much but it matters a lot if your setup is for for full body fur for animals. (Like the cats in 'Brudders 2', in which case you have a few tricky hoops to jump through to make it work--but I digress.)

4. Use Denis Pontonnier's MetaFit node to attach the guides. This works very well once it's done processing the object. The downside is that that if you have a lot of edges in your guides, it can take a long time to do the initial processing. If you close the scene and reopen, it has to re-calculate the processing--and this is before you do any Bullet processing. That said, the results are quite accurate. If you go this route, my recommendation is the bake the solution to .MDD immediately after you've run Bullet so you don't have to worry about processing in your master scene or during rendering.

There's probably something I'm neglecting to mention but I have to take off for a few hours. Hopefully, that's enough info to get you started.


03-25-2013, 06:25 PM
Thanks bazsa73 and Greenlaw - I'm going to give ALL of these suggestions a try. One or a combination has to work.

I appreciate the reponses!

03-25-2013, 08:23 PM
Sure. I've posted a few videos showing results but I'll try to create videos explaining actual workflow when I can make time for them. In the meantime, if you have specific questions about any video I've already posted, feel free to ask.


03-25-2013, 08:38 PM
Thanks Greenlaw.

I've watched a few of the Brudders test shots and really like the sister hair testing. I don't plan on having too much motion in shots (but you never know) and having the roots stay put would be fine. I'm mostly worried about trying to get the hair look like it does when skydiving - pushed way back and slightly flapping. I have a few shots with two characters that need this effect. Fortunately the hair IS parented to the head bone, so that means I won't have to worry about re-parenting.

Thanks Again!

03-26-2013, 09:17 AM
Try adding Turbulence or Fractal Noise to the strength of your Forcefield. Set the scale small enough to create tiny 'ripples' in the force. Alternately, you could simpy add some displacement to the baked .mdd after the bullet calculation.

In either case, use world coordinates if the character is actually moving through space. If the speed of your character falling causes too much 'rippling' (i.e., frequency) you may need to cheat this by counter-moving the displacement texture using a reference object--or parent it to the root of your character and animating the speed--or maybe your character is simply falling too fast. Lots of options depending on what you need. :)

BTW, I've seen Mr. Rid do some very realistic skydiving characters in LightWave about 14 years ago and I think all he used was bones and displacement (on hair and clothing). Sometimes a simple cheat is all you need.