A reader send me a link to the following video, which is an excerpt of an interview with physicist Brian Beckman. Here he discusses an upcoming indie / freeware game Rigs of Rods and talks a bit about what works and what doesn’t with physics engines.
He mentions making physics simulations “too complicated”, and I know exactly what he’s talking about.
But what’s really interesting here is the method they are using in this game. Beckman calls it “sticks and stones”. Now, this is a YouTube video of someone aiming a camcorder at a laptop, so I can’t be sure about what I’m seeing, but I’m fairly confident he’s using a technique I’ve used in the past, which is something I picked up playing the classic Bridge Builder game. (By the way, if you’ve never played Bridge Builder befoe, do check out that link. It’s simple, brilliant fun. And it’s free.) The physics in that game were pretty transparent, so I was able to learn a lot form just playing the game*. It used link points and joining lines, which I’m willing to bet is very close to the “sticks and stones” Beckman is using. (I’m sure the one in Rigs of Rods is a lot more robust, but I think they’re both driven by the same underlying ideas. Bridge Builder is actually 2D.)
I haven’t seen Rigs of Rods before, but I’ll be keeping an eye on it now. Fascinating stuff.
* I wrote my own version of Bridge Builder at one point, just to mess around with it. I didn’t bother making it a game – it was just a sandbox world. I added a couple of new tricks to the basic gameplay, such as rolling tires and cables, so that it was possible to build suspension bridges. It was a good learning project, which taught me that physics are harder than they seem at first glance, and that you can go a long way with the right combination of approximations.