françois puren

Hi everyone!

I'm having difficulties figuring out how to setup an effect I'm trying to do..!

Basically, I'd like to have the pig head to close his mouth and then/while closing it, to crumble in pieces.
I follow a basic tutorial from toadstorm [www.toadstorm.com], and as you can see on the flipbook, I've managed to make the top parts pieces to follow the animation done in SOP before simulation.
But as soon as I try to add more constraints (the red bypassed nodes), houdini crashes. If I unbypass them, and bypass the animation nodes (the blue ones) it also works "fine" (but still far from my needs eheh).

As it can be seen in my hip file attached, I'm quite new to the whole rbd world, and I'm obviously making things in a bad way!

Could anyone help me with this, pointing me where I'm making mistake, what I didn't understood, or what the correct approach to this problem I should follow?

Also, I have a simple (I think!) question... When I use rbd configure, it converts everything into packed geo/fragments... Where is the correct place to use that? Should I put it at the beginning of my stream and then create all my constraints etc. Or should I put it right before the solver?

Thanks to everyone taking the time to read this, and a bigger one to whoever could help me even slightly!
Cheers,
François

flipbook:
https://www.dropbox.com/scl/fi/1r05b7lgc5s25716mesit/test_rbd_pig.mp4?rlkey=2ivlf121a5cej4gmyx0zk8txg&dl=0 [www.dropbox.com]

hip file:
https://www.dropbox.com/scl/fi/u8jk6d34hb4ppo2z9rgd4/test_rbd_pig.hiplc?rlkey=e4ylr58c2nzw207gtu0y70h5m&dl=0 [www.dropbox.com]

Hi!

I'm facing a problem, and can't figure it out alone… (yes, that mostly always the reason someone post here i guess :p)

I'm trying to make some particles firstly go in a spiral motion around a curve (I've succeeded in this part with a line with edge_dir, then a wrangle with pcopen, and some cross products), but i want at some point (based on age) for the particles to end in tiny spirals… Like the effect in the frozen movie for exemple.

As my particles are firt moving in the XZ plane, i just made a first test by cross-producting the vel by an {0,1,0} vector, but evidently, as soon as my particles move in the Y direction, this method stop working!

So i think i just need some “up vector” from the particles, but that were i'm stuck!
The particles could be with any velocity direction and “spiraling” in any direction too…

So, does anyone knows how i could find this upvector, which should be pointing down when the particle is at the “top” of a spiral and need to get down, etc?

I hope i explained it well enough, sorry for my english!

Thanks a lot in advance!
François.

I will as soon as i can, thanks Arctor.
I was thinking (don't know how hard it could be) that an option like the “keep position when parenting” could be nice, like “keep position when blending” :p
I'm not a technical guy at all, but i guess it's a trick with inverse xForm matrices, right?