Hi guys,

I'm trying to simulate something apparently basic but it's taking me forever to understand how to do it right in Houdini.

My idea is to create an Egg that falls, breaks and instead of spreading a proper egg, it will spread some kind of colored confetti.

So far I created the Egg geometry (which I shattered and converted to RBD Glued object), the Vellum Grain source object (slightly smaller than the main Egg geometry, placed inside of it) and just a normal ground.

The problem I see is that if I get the Egg geometry and I make it to be Static Collider, then the Vellum grains work perfectly fine inside the egg but then the egg doesn't fall and break because it's not a Glued object?
If I make a Glued object, then this falls and breaks but the Vellum Grains don't interact with the Egg at all and both perform individual simulations.

My questions is why? Aren't RBD Glued Objects and Vellum objects compatible? Surely they are, aren't they? What's the kind of solver or route I should follow to achieve this?

Thanks a lot!

Gabi

Try separating the confetti simulation and the RBD simulation into separate object nodes. Therefore you can make one sim visible, and the other one off at certain times to view the simulation. You could then bring in the egg geo into the vellum simulation and then turn it off when the egg hits the ground. Hope this makes enough sense, and helps!

Thanks for your message Kate!

Do you mean having the simulation for the grains and the simulations for the egg in two separate Autodop? How can I make them work together? So far I have the egg object, the volume grains object (same egg but slightly smaller inside the egg object) and then all the relative objects that are generated when created Vellum objects. Is that what you mean by separating both simulations?

Thanks a lot,
Gabi

Hello,

Could anyone drop any additional comment or help me to understand why this isn't working? Any help or link to learn about it would be much appreciated.

EDITED: Just checking the Vellum help docs and I've seen this video in the header of the page (https://www.sidefx.com/docs/houdini/shelf/vellumgrains.html) which is very similar to what I want to do but how? How can I change that fabric bag with sand to a glued object that is broken is small pieces?

Thanks!

Have you found a solution?

You need to define the breaking points with the voronoi fracture would be my guess.
?

As for separating, you just make two separate dopnet’s for each simulation?

Hey Xtro,

Thanks for your reply!

I tried having both solvers (one for the RBD and one for Vellum) under the same AutoDOP but they didn't interact each other. They were both working individually but the grains weren't affected by the eggs pieces at all. I didn't try to get both solvers in separate DOPs for several reasons. First, I don't know how to do it lol and second, something tells me that will not work cause if they don't work under the same DOP, why then they'll do it in separate networks?

It's weird cause if I convert the egg to a static collider, the the grains inside the egg stay there but as soon as you shatter and make a RBD object, then the interaction between elements stops.

I have read in other forums that RBD Packed Objects and Vellum objects aren't working together. They said that you can have them under the same network but their simulations will only work individually. Not sure wether this was a issue in the past and was fixed in latest versions or this issue is still happening.

Thank you for your reply! What do you think?

Gabi