nHair mass

[mikael persson]

Hi group,

how is it with nHair, which is the best way to calm down strands of hair that have been hit by other dynamic objects?

I'm simulating heavy cables that get torn away. But can't seem to control the strands that well.

The weight, dynamic weight and gravity doesn't seem to do much, the difference between 1 and 1000000 is hardly noticeable.

Damp and drag just freezes the cables and motion into boring staticness.

I know how hard it is to help someone with their dynamic simulation but maybe I'm missing something obvious?

Thanks for the help!

Mikael

[mikael persson]

The obvious thing being, check the gravity on the global nucleus solver and not on the individual hairs!

What does the gravity on the individual hairs do if it does not affect the connected strand of hair?

I hope I save some time for someone else...

Mikael

[Duncan Brinsmead]

I’m not sure what you mean by “gravity on individual hairs”. The per hair dynamic attributes are the follicle dynamics override attributes, otherwise one uses attributes on the hairsystem or the nucleus node. The gravity should only come from the nucleus solver unless you have an additional gravity field.

If the hairs are too springy you can use stretch damp and a small amount of damp. For heavy cables there should be no drag. Also you may wish to make the bend resistance zero or near zero. The stretch resistance should be relatively high. As well you may need to increase the substeps on the nucleus node if you have a lot of segments or it will be too stretchy + bouncy. If you are modelling in cm then set the gravity to 9.8 and the spaceScale to 0.01 for a realistic level of gravity.

 

Duncan

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[mikael persson]

Thanks a lot Duncan! These variables you mentioned helped a lot, substeps and space scale did wonders. The stretch damp did help quite a lot even though I couldn't go too far with it as it started affecting things in an undesirable way. But I could remove the worst jelly bits at least.

When I spoke of gravity on individual hairs I meant the gravity variables on the hairSystemShape. There seems to be quite a few perParticle attributes on these shapes, how do I go about turning on perParticleAttributes on the hairSystems?

Once again, thanks Duncan! With these tweaks I managed to get a good result out of the sim.

Mikael

[Duncan Brinsmead]

The gravity variable on the hairSystem is only for the old solver, not nucleus, which uses the gravity from the solver node. It should be hidden in the attribute editor if you are using nucleus.

The only per particle controls on the hair are affected by the stiffness scale and attraction scale ramps, that let you control vary those properties from root to tip.

As well there are the dynamics override attributes on the follicle that let you affect things per hair. One can’t directly set per particle dynamics attributes on hair, however.

It is only indirectly through the controls on the hair system and follicle nodes.

 

Glad you got your sim working.