Hi everyone, I'm a bit of a noob here, and I'm trying to instance debris to particles. So far I've managed to do it with the copy sop, but I don't know how to control the rotation of the pieces, and when they land the pieces shake, and before stopping all the pieces turn to the right, really odd and a bit funny behavior lol. Also because it's geometry instanced into particles, when they collide with the ground, the pieces go through a little. I will attach the file that I'm using.

I don't even know if using the copy sop is the right way of doing things, or if I should look at something related to RBD.

Please help, I'm self taught and It's kind of hard sometimes.
Thanks

Add a normal SOP (set to points) and a attribute randomize (pscale) after the “Particle_Emitter” SOP. Change “Particle_Emitter” to be polygon, not primitive (so you get different pscales for the birthed points).

Make sure in the copy SOP you are have “Use template point attributes” turned on. Bypass the “Scale” SOP to see that the rocks now don't go through the surface.

If you want tiny rocks, (randomly scaled), make the pscale go from .1 to .2 instead of the default 0 to 1.

The reason you are getting the popping right now is that Houdini uses the velocity vector to align the copies if no other usable attributes exist. The simplest way to fix this is to add an N attribute to your source.

Of course, you will not get rolling behaviour when the particles hit the ground. For this you should use RBDs, or you can try the not very user-friendly distance based rotation idea used here: https://vimeo.com/277642002?from=outro-embed [vimeo.com]