Tutorial: Vellum Grass (Basic Plasticity)

Hi Everyone!
In this tutorial I create a grass patch in sops and simulate it with vellum as hair strands. I then go through using plasticity to make the grass stay in place when bent by collision objects. As a bonus I also turn the collision object into a dynamic vellum object at the end.
For more tutorials like this check out my Patreon page: www.patreon.com/zybrand

[@PunmasterSTP]

Basic plasticity? More like "this has got to be" some of the coolest simulated grass I've ever seen. Very cool; thanks for making and uploading this!

[@mdp7193]

Amazing, thank you!

[@mightyshrimp1221]

This was a great tutorial!! Thank you so much for making this!

[@tilakrajgolari1577]

Thank you,Sir.

[@massimobaita7178]

Thank You very much!

[@lemmonsinmyeyes]

Epic, thanks for sharing!

[@DreamTeam-yk2ff]

awesome !!!

[@tondann]

I learned a lot and by the way that render is just fabulous, looks photoreal!!

[@zybrandcg]

Thanks Anton, glad to hear that

[@user-qe8we6iy3z]

Thanks, great tutorial

[@NathanTekaya]

Thank you !

[@mac231000]

This is sooooo cool hope you good buddy, been looking for something like this to brush up on my houidini

[@karo_dr1p_fx]

if your grass goes completely nuts when you try to simulate it (did for me in h19), try putting the color nodes after the vellum solver.

[@zybrandcg]

Not sure what it would be, a lot of things can make vellum hair go nuts.

[@karo_dr1p_fx]

@@zybrandcg very true, I'm still figuring that out project by project. Vellum is an interesting one :D Nevertheless, amazing tutorial! Thanks for that

[@jancordero7045]

Thank you so much for this! Had one question though. When adding the vellum cloth and the rest of vellum nodes to the sphere and finally getting the animation running the grass is sticking to the ball as if it had lots of friction. To the point where the grass gets insanely long and bad. Cant seem to see how to make this work. Any ideas?
Anyways, great tutorial, thank you!

[@joshuamallek1937]

Add more Edge Length Scale and check for any intersections in your geo at the start of your simulation

[@celestesanja5836]

I had the same problem, but solved it by moving the sphere further away on the x axis, so it doesn't touch the grass at frame 1.

[@nictanghe98]

anny way to not render as a tube but as geo ?

[@jamesli3705]

Hello, I don't understand why the "Attribute Adjust Vector" node uses Points, but the "Guide Process" node is using primitives. I thought we were controlling @benddir with a point attribute? So, when I change primitives to points, these lines don't bend..

[@kavumayahaya7060]

Did the plasticity in 19 change?

[@Reebert02]

My grass isn't bent as it is at 5:52. I'm presuming that this is because Houdini changed the "Attribute Adjustment" node in V19. The "Adjust With" option isn't there. Still learned a lot of cool stuff though! Thanks!

[@zybrandcg]

Thanks I am glad you found it useful :) . That weird I had a look at my scene in h19 and it's still working.

[@powercou]

I can find the 'Adjust With' option but my grass doesn't bend either. Can anyone help?
Edit: added a fresh 'attribadjustvector' and it worked fine.

[@joeyparenti7815]

question literally when I try to enter the vellum solver I dont see the null control

[@zybrandcg]

Hi Joey, not sure I follow which part of the tutorial are you talking about?

[@bondell1840]

Is there a way to attach the vellum hair to an rbd sim that i had cache?

[@zybrandcg]

I haven't tried that yet but depending on what you are creating I would rather create the rigid bodies in vellum as well with the shape match constraint and attach the hair to that.

[@zoeychen8487]

I am not sure why but after I after I merged them and try to see the frame , the sphere is deforming and goes in nuts, before merging it works fine, but I follow your tutorial step by step, does anyone know what went wrong????

[@zoeychen8487]

I mean merging them into vellumsolver

[@psclip3309]

polywire invalid attribute "pscale"

[@traceurAlex]

and mine is still falling like spagatti! 😕

[@joseescc]

make sure you are working with the right vellum hair

[@powercou]

I put the bend stiffness from 0.1 decimal at 3 to a much higher number like 30 for it stop falling over.

[@Popkill_]

To anyone having the same problem : change also the stiffness stretch, it should be 1 scale : 1e+10

[@traceurAlex]

lol was following along this "basic tutorial". after you add the first sop.. 👀 wtf just happened.