Blowing up naked guys

Houdini Crowds and Explosions RnD - Blowing up a bunch of naked men from Trond Hille on Vimeo.

At Siggraph I briefly saw a part of a presentation where some guy (I'm sorry I don't remember who it was) did some RBD explosions and having crowds running through, being blown up. I had some time to kill today, and it was about time I did another RnD session in Houdini. So I figured I'd give it a go! Had a lot of fun with it, but things started getting pretty slow at the end, so didn't tweak it much. More a proof of concept. I realize I barely dipped my toes in the crowd system, but it was pretty cool. I'm working on a Star Wars scene on the side, so I'll probably incorporate the same crowd behavior there later.

Anyway, this was a great exercise on many levels. First I set up a completely procedural RBD destruction setup. It was tricky to get right, and there's always these ting you forget. Like Metaball forces are inverted! I kept tweaking settings and for the life of me I couldn't get it to behave properly. It wasn't actually until I got to the crowd setup and seeing those poor men being sucked into the explosions I remembered that I need to invert the force! Damn.. I did this whole custom workaround setup with a SOP Solver to get around it. But happy I figured that out at the end. 

Adding forces to the crowd sim wasn't very self explanatory either.  I tried adding the pop force all over the place, until I found it working below the Crowd solver. A bit strange.. 

Also I can't help think there's a better way to bring in the RBD sim. I brought it in as a deforming static object set to concave. It of course made things really slow. I deleted all smaller pieces to speed things up a bit, but yeah, that was a major hit on productivity. And my goal was getting something done and out in one night. 

At the end I got everything working fine though. Next would be to tackle the pyro explosions.. Hope I'll get to that soon