And not take the whole ceiling with you?

I'm trying to setup a sim in which a character falls through a ceiling. I've pre fractured it and setup a glued rbd network. The trouble is once my character steps on the fractured geometry the whole thing starts to fall! Is there a way to prevent pieces from falling until they've been hit by the character?

I seem to recall an example file somewhere on the forums with a few pre fractured cubes and a sphere that hits the cubes but only a few bits of the cube fall..? I remember looking at it quickly and thinking “oh that's so easy!” Maybe an activation threshold or something?

Needless to say, still pretty new to Houdini. Any tips greatly appreciated!

Why is it that posting to the forums seems to jog my memory?

I think the min_activation_impulse is the answer! Set the object to be static initially then use that value to switch pieces from passive to active.

I found the file to which I was referring! Of course, it wasn't here- twas on the odforce forum!

https://forums.odforce.net/topic/24182-bullet-activate-on-collisions-or-start-sleeping/ [forums.odforce.net]

The3DStig
I found the file to which I was referring! Of course, it wasn't here- twas on the odforce forum!

https://forums.odforce.net/topic/24182-bullet-activate-on-collisions-or-start-sleeping/ [forums.odforce.net]

I would use the active attribute. you can even keyframe it or set it with a volume linked to your character feet.
there is a nice tutorial in the learning section:
https://www.sidefx.com/tutorials/how-to-control-fracture-simulations/ [www.sidefx.com]

Always good to add some Varomix tuts to my learning resources, thanks!