Anyone can help me in Houdini (glue)?


First i’m feeling weird because i’m posting a lot of questions here, thanks to all for your help. I’m learning by myself Unity / Unreal / Houdini and sometimes, I have some problem and there is always someone who helped me so thanks a lot !!!

Today I’m working on a big project. A meteor is crashing on a monument which crumbles afterwards.

I’m using a glue constraint and the problem is that the debris don’t fall to the ground and stay like the screenshot.
Apparently, the fact that the glue keeps all the debris together also keeps them from falling once hit by the meteor.

(ps: I did the rocks and ground collision, I just need to understand how can I have the debris fall to the ground).

I know that’s a real time forum, but maybe someone can help me.

Thank you !

First thing I would check is the Bullet collider created from the rock geometry and make sure it’s not creating one large convex hull for them all. (which is the default behavior).

StaticObject node → Bullet Data tab → Show Guide Geometry checkbox.

If it is creating one huge collider for them, turn on “Create Convex Hull per Set of Connected Primitives” which will make convex hulls for each rock separately, or try a different method using the dropdown (like “Concave”)

It looks like the constraint network is wired up incorrectly, (unless something has changed since I was deep in RBD land, I don’t use the shelf tools).

Try moving the constraint network to be after the rigidbodysolver. Also try changing the color of the guide options to make sure that those glue constraints are really even in there… since they aren’t breaking. Also you probably need to plug in a sop solver into the constraint network so you might as well be prepared to start your master’s thesis in rigid body destruction.

Anyway, I recommend getting the glue to work with a small scene first then transfer the ideas to the larger scene.

Hello !

First, thank you for your help !
I’ll be trying your solutions now and will comeback soon.

The project is a course that I paid on Udemy. The nodes are the same that what he showed. When I create the glue contstraint I already have an error (and in his tuto too but he keeps going and in the next video the final result is super pretty).

The middle output doesn’t contain any pieces which is what gives the error. That’s the constraint prims. I can help you debug if you jump on the discord. Easier than through forum posts.
But I would start looking at Adjacent Pieces from Surface Points driven by the render or proxy geometry instead.

Hannn I’m french and it’s hard for me to understand 100% of english. :confused: (I’m learning hard !)
I just can chat with you on discord ? My boyfriend is english so he can stay next to me and traduce haha.

My VFX professor at school helped me today, he said that the constraint are ALWAYS after the solver because of the logic.

I just already have the connectadjacentpieces problem.

He put my static object on concave to accurate the collision. (Hope you understand what I’m saying. haha, I’m not using any translator.

There’s a Houdini channel on the RealtimeVFX discord with plenty of people who can help. It’s just faster to troubleshoot through there. It looks like you got help anyway though so that’s great!

I still think that connect adjacent pieces and active attrib to dopimport setup is very odd, but if it works for you, go for it!

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I don’t know, i just followed what he said to do on his course. Need to resolve this error. I’m going to the discord :slight_smile: