How to Simulate Plants in the Wind in Houdini

Wind simulation is very easy to setup in Speedtree. What you may not have know is that is easy to setup in Houdini as well. Today we look at how to simulate plants in the wind in Houdini using the Vellum Solver.
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[@RMAFIRE]

Thank you for sharing your art💯🖤

[@VisualWondersPlayground]

Amazing bro

[@OX_Tools]

thanks, this was helpful in getting some grass animated.

[@InsideTheMindSpace]

Glad you found it useful

[@kir11]

Nice!

[@velcrolog]

Amazing, simple tutorial. Thanks for sharing. How would you go about applying this technique for a full field of plants or grass? More precisely, keeping it procedural (without having to export pre-rendered animated loops).

[@InsideTheMindSpace]

If you want to go that route you probably want to do it to each type of plant first and then scatter them instanced across the terrain or whatever.

[@Sewsi]

Hi , struggle a bit with it . When I follow the tutoriel with a megascan asset, the asset brake. By that i mean the branch brake , petal fall. I guess it's because the asset is made of multiple object and the point are not connected. I read in the comment section that you talk about a glue parameter / strut setting but i don't figure it out and i can't make it work. Any idea how i could "Glue" the model together so it don't brake within the animation ?

[@InsideTheMindSpace]

The strut settings are going to be what you need to mess with. They are what hold everything together. Scenes are going to vary wildly in settings but the struts are what you are looking for

[@Sewsi]

@@InsideTheMindSpace Hmm , so it should be the VellumStruts right ? If it is, no matter what parametre i put in it nothing happend. And i have the same result without it so it look like it doesnt have any effect on it . I used 3dplant_shrub_wf0oefeja on Quixel bridge asset as a plant. Thank for the time you put to respond, and sorry for the question i did not find the answer online :/

[@InsideTheMindSpace]

The setting should be the struts. Every situation is going to be a bit different. You may need to evaluate what is happening with the struts to figure out what is going on. If I remember right you can wire the middle output into a null to view the struts and what is happening as it's simulated

[@cass5710]

@@Sewsi I know it's late but use the weld vellum contraint with leaf base points and the stem as target geo

[@metaturnal]

By any chance, what do you do if you want to feed different variants of these into a scatter setup to sim them afterwards?

[@InsideTheMindSpace]

Probably need to setup the constraints and everything and then scatter them but I would be hesitant to do it that way as the more geo that you have the harder it will be for it to sim

[@metaturnal]

@@InsideTheMindSpace If I were to that, how would I? Do I just merge all the constraint outputs together? If I create a scatter set up, I usually place all variants at the center of the scene and merge them. If I do that, won't it create constraints as if it were one complex plant instead of separate ones? I just don't understand how to feed all of that together, in general.. Otherwise, since you said it would take long to simulate, what would the alternative be? The reason I want to simulate it with, vellum is that I have an object that is supposed to move through the grass, and move it out out of the way. The rest I will just animate with a noise.

[@InsideTheMindSpace]

Thats a more complex setup than it seems. It's been some time since I messed with that type of a setup and I remember running into a lot of issues. The constraints nodes just create attributes on the geo that the sim looks for. It will take a good amount of fiddling to get things right. You might be able to scatter everything and then add constraints and sim but it might take awhile. You could potentially sim one object at a time but you would have to get creative to get the sims to interact. Merging the constraints might not work because there's three outputs and a merge would only give one output. You could try merging each output with the other of the same type. Honestly not sure what the best solution is for this. That is also something I have had the desire to do but I've never gone back and actually took enough time to figure it all out unfortunately

[@InsideTheMindSpace]

There is also another technique that I have seen used for similar things that isn't as accurate but does work. I believe that involves converting everything to a line essentially to use as a basic geo and then running that through a sim and then using a point deform or something to get that movement applied to the final geo. Been awhile since I saw that as well but you can probably do some hunting and find that technique

[@metaturnal]

@@InsideTheMindSpace Thank you for taking the the time to answer me in detail. I will see if it works on a small scale and then increase the copies. Otherwise I might go another route.

[@raimuhammaduzairfareed7628]

👍👍

[@hendasheng]

Thanks for your tutorial, I followed your method to make it completely, but with the swing, the leaves and flowers of the plants will fall off. How can I fix the leaves and flowers? I am using Houdini 19, looking forward to your reply, thank you very much.

[@InsideTheMindSpace]

You probably need to adjust the glue strength so that the binds holding everything together dont break

[@hendasheng]

@@InsideTheMindSpace Thanks for the reply, what does "glue strength" refer to? I tried adjusting "Stretch -> Stiffness" for "Vellum Cloth / Vellum Struts", but it doesn't work.

[@InsideTheMindSpace]

Sorry glue strength is a different constraint type. You need to mess with the strut settings I believe.

[@hendasheng]

@@InsideTheMindSpace Thanks for the reminder, I just started learning Houdini for two weeks and I think I know where the problem is, thanks again.

[@loganpenciu7317]

TUTORIAL WORKS: I followed your tutorial to a T and nothing is happening. My timeline is filling up with the blue bar signifying that it's calculating the sim but absolutely nothing is happening. Please help? I'm in Houdini 19.0.383. I'm also a novice with Houdini I only have 2 months of learning but I figured this would of been simple. My plant is an alembic brought in from C4D, is that an issue? UPDATE: I tried it with an FBX and it worked fine :) How can I bring in an alembic and use this technique? I would like to know for the future. Thank you so much for the tutorial!

[@InsideTheMindSpace]

Alembic come into Houdini as packed geometry by default. You may have to unpack the geometry

[@raimuhammaduzairfareed7628]

Which one will be good to use animated trees in project Simulation in houdini and export to clarisse Or Animated trees in speedtree and export to clarisse

[@InsideTheMindSpace]

I would do speedtree because while it is possible in Houdini it is going to be more work for trees in Houdini

[@raimuhammaduzairfareed7628]

@@InsideTheMindSpace thanks brother for help Your tutorials are helpful for me

[@InsideTheMindSpace]

No problem. Just happy to help people learn