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"Solve, or nearly solve, partial differential equations". That's game physics. Most of the effort is to come up with ways to "nearly solve" without having awful stuff happen. There's a long history of awful stuff, going back to when Seamus Blackley botched Trespasser in 1998.

Game physics still tends to go "boink", because with impulse/constraint collisions, everything, including large, heavy objects, bounces instantaneously. Stuff flying apart, though, is rare now; most systems drain the energy out of a system when they detect that happening. It's physically wrong, but looks less awful.

I used to work on this stuff. I solved the "boink" problem for articulated rigid body physics in the 1990s, but couldn't make it work in real time on 100MHz CPUs.




> Stuff flying apart, though, is rare now; most systems drain the energy out of a system when they detect that happening. It's physically wrong, but looks less awful.

Most games are using position based dynamics now (see Nvidia PhysX) so there isn't even a variational principle to arrive at the system from an energy. Just a constraint satisfaction problem with a weak notion of momentum coupled in.


I loved the physics in Trespasser. Good times.




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