Hi there,
I have been using Houdini for a year now but never touched on particles since I've been using it for game asset creation. I started to look into a bunch of tutes but can't figure out a bunch of things so I thought I might ask a few questions at once.
If any particle masters out there have a sec to check them out it'd be great!

Can a particle be an instance of a mesh? (and is that viewable in the viewport or only at rendertime).
Can particles scale or rotate based on velocity (or other attributes).
How do you handle events, say if I have a rain drop that hits the ground, is it easy to spawn a splash from that?

Thanks,
Pete

Particles are just points so you can copy an instance onto the point.
You can always use a PopWrangle to make custom modifications to rotation or other attributes.
There are hitcounts that you can review inside a PopWrangle to decide new actions,(i.e. move the particle to a new group with forces only affecting that group).

If you have not checked out the Rain HDA on orbolt, it has some nice features such as particles falling, colliding with other meshes, drops running down a collision surface and forming drops when they hit the ground.
http://forums.odforce.net/topic/25935-houdini-15-rain-effect/?do=findComment&comment=150980 [forums.odforce.net]

Wait a sec. Did they change the way particles work or something, I'm having trouble recreating my own system like theirs
When I make a particle system it creates an AutoDopNetwork and that seems to have different collision nodes and no split node to create the different states like in the rain demo. Maybe the rain one is out of date?

Rain Demo ? Post up a scene file

Rob

Ahh sorry, it was this one -
https://www.orbolt.com/asset/SideFX::vfx_rain [orbolt.com]

Okay so it looks like that is the old way of doing things.
I think I'm starting to get it now, but I am not sure how I would spawn some new particles from the hit here? I tried to create a new pop source and but I don't know how to point it to the collision points for it to spawn from.
Also I'm not too sure how to create different instance geometry for the different stages. For example you might have a rock as the primary instance and smoke clouds as the trail particles.

I attached the scen in case anyone feels like checking it out.



Particle Scene [peterleary.com]

Thanks,
Pete

This isn't brilliant by any means, but might give you some ideas of how to separate out the different elements using streams/groups, then how to use those to instance geo after the sim.