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Julien Moreau

Houdini constraint make the simulation freeze ?

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i am currently working on my final student projet where i make a plane crash with Houdini. I base the workflow of this project around the RIGIDS III tutorial by Steven Knipping. Everything is working fine until i bring in a simple glue constraint, and when the simulation gets activated at a said frame the simulation simply does not happen. It works when i disconnect/disable the constraint. 

I already tried to unpack the alembics upon importation with the alembic node but that didnt change anything.

What is weird is that everything was working fine when i used the model given with the course. I haven't really found anything that helped me online, so hopefully one of you can help me with this issue, i would appreciate it A LOT.

I will attach the files down below.

Thank you !




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hey Julien,

I saw a couple of problems in your sim. 

1. The "set active" wrangle in the sop solver was set to primitives and should be points;

2. you had some zero masses on your points which is what is freezing your sim. It probably means you have pieces with no size. so you can either clean your geo or just add if(@mass==0)@mass=1; in the "set active" wrangle.

that will make it work.

Also when you make your constraints, I would personally add a facet after the connectadjacentpieces1 sop and check unique points. The will give each primitive a unique set of points which make them easy and clean to delete, plus you can scale them to zero if you want to use hard constraints.



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