Hair Dynamics (While character with hair moves - hair moves around the whole body)

Can someone please explain to me how hair dynamic work?

I mean, I have a hair length of 0.005 and when I play my animation with my character with hair sometimes the hair gets like 1000 times longer than it ever could’ve been.

Is hair dynamics just a piece of crap - because how can any hair at any point grow a 1000 times in a 1/24 of a second?

No matter what I do with Hair Dynamics, the hair on front of the body goes through the body and makes the back extra hairy and then disappears totally on the front of the body and magically appears through the body.

I can’t for the life of me understand this thing without someone explaining what I’ve done wrong. Or maybe I just missed a key point in physics that say that your hair can grow about a 1000 times in a nano second under certain conditions.

And there’s no good tutorials about any of this…

Hair Dynamics as currently implemented has no collision. That is, the hair particles will move through any object as if they are not there.

In my opinion, it is not suitable for long hair.

It does have, however, some applications to short, very stiff hair.

It’s short and stiff hair, fur on two characters. Do I have to add some Collision to the characters Mesh so that it bounces back?

Sounds like perhaps you’re using settings that allow for a lot of stretch in the hair strands, but it’s hard to say without seeing them. Also, the position in the Modifier stack of the hair Particle System in relation to the character’s Armature is critical – make sure the Armature modifier is above the Particle system.

Collision has no effect whatsoever on Hair Dynamics in particle hair. Adding collision to the character mesh will have no affect on the hair.

how do you make the hair not intersect the mesh while in dynamics

Some people have had luck with a surface force, but I haven’t made much progress there.

I use a build of blender with a patch that adds cloth collision to Hair Dynamics. It’s not great, but it works, more or less.

I have two characters:
Character 1’s Modifiers: Armature, Smooth, Particle System #1, Particle System #2 (Emit)
Character 2’s Modifiers: Armature, Particle System

(In that order, top to bottom)

I just want the hair to simply “move” like it should. It’s stuck on the surface of the mesh, and when the character moves so does the hair. Also, I don’t want every hair just to “fall down”, I want them to move slightly when moving. Like a hedgehog’s pecks but a little more movement so you can see that it moves.

Hair length is like 0.005 and the hair can when using Hair Dynamics be extended about 100 times… I don’t understand it at all.

Also, the same thing happen to both of those characters even though they have different modifiers.

Post a screenshot of your Hair Dynamics settings, please. It’s impossible to troubleshoot a problem without proper information. If possible, post the .blend file.

Can you point a link to this?

Wasn’t hair dynamics working prior to 2.5 series? (or working better -I thought there was at least basic collisions before?) If so, couldn’t you just use an older version of Blender to render out just the hair sim and then composite it back into the scene?

This could be horribly complex depending on the scene, models and hair systems. Probably better just to use 2.49b (and Softbody hair) for the entire project. Better yet, get hair up to snuff in 2.5/2.6 – that it is being essentially ignored is a mistake IMO.

Idk I think compositing can seem a lot more complicated than it actually is. I need to find a solution for hair myself because I’m going to be working on a project soon that will make a lot of use of it. If I animated a character in 2.6 would it still be importable into 2.49? I know the animation system was changed.

@Rhynedahll Thanks I’ll check it out.

I’ve done a lot of compositing, including the kind you’re speaking of, and believe me, there are many non-obvious considerations involved. I won’t try and dissuade anyone from trying, just want to state that it can be a major undertaking for a number of reasons, maybe more than is necessary if the job can be done wholly in 2.49b.

No retro-compatiblity for animation – you can adapt 2.4x for 2.5+ but not the other way 'round, AFAIK. Besides the animation system changes, there are significant differences in the rendering pipeline, how things like AO are handled, etc., that can affect how dual versions can be used effectively.

My settings are the standard settings, or whatever I change it to it still gets the results similiar to before.

Settings on Particle System:
Number: 2000
Emit From: Volume
(X) Random (X) Even Distribution

Normal 0.005

Size: 0.05

Strand Render
B-Spline: 3 Steps

Display: 10
Render: 200

Endpoint: 0.120
Random: 0.02

Vertex Groups:
Density: Body (where the hair should grow from)
Length: Body (where the hair should grow from)

Need the Hair Dynamics settings, which affect how the hair reacts during animation.

As I stated before, I haven’t changed it and it still gets the same effect.
When you start Blender, create a Particle System and enable Hair Dynamics - that’s it. It doesn’t work, and I don’t know it well enough to understand. But everything from the standard settings just made it worse, or seem like it.