[Solved] How to get interaction between Vellum Hair and Grain

[underscoreus]

Howdy folks!

I've recently started looking into Vellum and I am currently trying to create interaction/collision between Vellum grains and Vellum Hair however it does not seem to come as easy as interaction between grains and cloth.
I've used the same setup that worked with my grains and cloth example to make this setup however as mentioned above so far I've had no luck in making it work. I am sure that there is something very basic that I am missing here but I can't seem to find it. Any ideas?

Screenshots of the setup(Sorry for less than optimal/clean node layout):
Scene file as well as base model too if you'd rather dig into it.

Vellum_Hair_Grain_Test.zip

[Noobini]

could be wrong but from memory, VellumGrains need a real geo (surface  or volume) to collide with. Hair is nothing but a line so it won't collide, Grains is particular about this I think, can't for the life of me find the thread anymore. Search function on here is a bit finicky.

Edited May 5, 2020 by Noobini

[underscoreus]

4 minutes ago, Noobini said:

could be wrong but from memory, Grains need a real geo (surface  or volume) to collide with. Hair is nothing but a line so it won't collide, Grains is particular about this I think, can't for the life of me find the thread anymore. Search function on here is a bit finicky.

Hmmm, and this was for when both grain and hair was Vellum??
If so that's a little annoying. Not entirely sure how I can copy geo onto the vellum hair points and still have them work properly in the vellum sim.

[Noobini]

yeah both grains/hair were using the same vellumsolver.

An even easier test to try before you buy is: line/hair...copy transform a bunch of them, drop grains on them...goes right thru

Then you'd try to be smart about it and put grains on the hair ! Then grains would collide against grains. but I don't think this cheat is good enough for anything except a few giggles.

Edited May 5, 2020 by Noobini

[Noobini]

..some fake grains/hair collisions...

Edited May 5, 2020 by Noobini

[underscoreus]

25 minutes ago, Noobini said:

yeah both grains/hair were using the same vellumsolver.

An even easier test to try before you buy is: line/hair...copy transform a bunch of them, drop grains on them...goes right thru

Then you'd try to be smart about it and put grains on the hair ! Then grains would collide against grains. but I don't think this cheat is good enough for anything except a few giggles.

Hmmm, I'll try this out and see how far I can push it!

Thanks for the tip!

Guess I'll update the thread with whatever hair-brained scheme I come up with if I succeed!

[anim]

I'd think it should work, definitely submit RFE for that as there is no obvious reason why they shouldn't interact natively unless it's a technical one

what you could do in meantime (and this is sort of a hack, but may work depending on the case) is set i@isgrain point attribute on your hair to 1

you'll still get hair constraints applied, but point to point collisions on hair as it's now disguised as grain

the disadvantages I forsee is, you lose hair segment collisions and maybe some grain forces like clumping will now affect your grain hair, but in some cases for visible interaction it may be worth it

ts_vellum_hair_grain_interaction.hip

Edited May 6, 2020 by anim

[Noobini]

2 hours ago, anim said:

I'd think it should work, definitely submit RFE for that as there is no obvious reason why they shouldn't interact natively unless it's a technical one

what you could do in meantime (and this is sort of a hack, but may work depending on the case) is set i@isgrain point attribute on your hair to 1

you'll still get hair constraints applied, but point to point collisions on hair as it's now disguised as grain

the disadvantages I forsee is, you lose hair segment collisions and maybe some grain forces like clumping will now affect your grain hair, but in some cases for visible interaction it may be worth it

ts_vellum_hair_grain_interaction.hip

ahhh...much quicker than me setting grains on hair manually.

[underscoreus]

18 hours ago, anim said:

I'd think it should work, definitely submit RFE for that as there is no obvious reason why they shouldn't interact natively unless it's a technical one

what you could do in meantime (and this is sort of a hack, but may work depending on the case) is set i@isgrain point attribute on your hair to 1

you'll still get hair constraints applied, but point to point collisions on hair as it's now disguised as grain

the disadvantages I forsee is, you lose hair segment collisions and maybe some grain forces like clumping will now affect your grain hair, but in some cases for visible interaction it may be worth it

ts_vellum_hair_grain_interaction.hip

That is hilarious and awesome that that works!

Thanks a lot, o grand master Anim!

[HM_2020]

On 5/6/2020 at 5:46 AM, anim said:

I'd think it should work, definitely submit RFE for that as there is no obvious reason why they shouldn't interact natively unless it's a technical one

what you could do in meantime (and this is sort of a hack, but may work depending on the case) is set i@isgrain point attribute on your hair to 1

you'll still get hair constraints applied, but point to point collisions on hair as it's now disguised as grain

the disadvantages I forsee is, you lose hair segment collisions and maybe some grain forces like clumping will now affect your grain hair, but in some cases for visible interaction it may be worth it

ts_vellum_hair_grain_interaction.hip

Cheers Tomas! Cool stuff, does not seem to work in 18.5 though...any ideas? Cheers!

 

[ftaswin]

On 11/30/2020 at 10:22 AM, HM_2020 said:

Cheers Tomas! Cool stuff, does not seem to work in 18.5 though...any ideas? Cheers!

 

It does, but the default mass on grain is way too high.

ts_vellum_hair_grain_interaction_adjusted_mass.hipnc