Hi, i have some question about Spring SOP

i using spring SOP to make the hair drop down and collision with the model.

but there is a probelm, the spring will pull the hair to become longer, for example my hair is 10cm, but after spring SOP it may become 50cm. (show as the image bellow)


i want spring SOP moving the particle but without elastic, so the hair length didnt change, how can i do that ?


thanks

cheers

there is Spring Constant parameter in Spring SOP which is something like Stiffness
set it really high to avoid elastic feel
but to make it stable, you also need to decrease Time Inc parameter
there is also Drag parameter you can increase to get smoother motion

thanks for reply but Spring Constant parameter doesn't really help bcs it still making the hair become longer if i set the force become bigger, i would like to just move the particle but without any elastic.

I think you would want to use the Hair solver in DOPs instead?

hi edward, not DOP, i wish i can done that in SOP. bcs many points is swimming.

maybe if you can attach sample file so we can see where the problem is
because i have no problem with Spring Constant
it depends on mass and force size, but you can set it very high if you need to

thanks for replying

as the hip files show the fur is base on a sphere who are always switching scale refer to rand($F).

and as the hair.PNG show that i want the hair shape is always in that shape whatever what size the sphere is.

i make some change in “OBJ_hair/clumps/__dispaly_sop__” to control the hair shape,i not sure is this the correct way to control the hair but i figure out this work.

and the sphere size was random in every $F, and i want whatever what size is it, the hair is in this shape as hair.png, and in the correct propotion but not changing propotion. (because the human model i use have alot of swimming point and unstable point in different frame)

what happen in this HIP files is, the hair continue fall down none stop because of the force, the more $F it is, the more longer the length of the hair, i would like to know is there anyway to make the hair fall down but not making the hair become long.

i have try to use Lock, yes, it work, but only for certain frame, some frame the hair is disappear, i don't know why.

i hope you can help me to figure out a way so i can control the human hair on a unstable model correctly.


thank you thank you very much.

sorry that i forget to make some change to the geometry, please allow me to upload again this files.

I have modified your spring SOP
Tine Inc: /10
Spring constant to 3000, you can tweak this for your actual scene

but most importantly you must specify Fixed Points
you didn't have one, so the hair was falling down and therefore generated fur was just longer and longer

i don't recommend you rand($F) because it produces sharp steps and no simulation likes this.
You better have deformations that can be resolved between frames like noise() or probably your character animation

if you want hair to keep shape, you heed to use wire dop simulation

thanks alot, i think this is really helpful, i think i will just need to do some more adjust in the real scene.


thanks so much!!

thanks alot, i think this is really helpful, i think i will just need to do some more adjust in the real scene.


thanks so much!!