Physics [split from network thread]

[stenyak]

Here you have some interesting readings:
http://www.motorsport-sim.org/mediawiki/...ks#Physics

And don't miss this one, it's pretty good:
http://www.carbibles.com/suspension_bible.html


Camber changes are pretty important in a simulator, it's the reason why i called "up-down suspension" game-ish. Of course this is all relative, depends on how realistic you want your sim to be, and how much time you can put into it.
Maybe a constant-camber suspension is appropriate at the moment, knowing there's not even car to car collisions, which i think are more important if you're thinking on actually racing instead of hotlappging.


Regarding physics freq... the physics rate *always* changes how a simulation behaves. And, given a certain physics model, higher frequency always means a more realistic sim (except for, sometimes localized errors, which are not the norm, but a coincidence). The accuracy (or what we detect as being accurate by watching a screen) of the simulation doesn't linearly increase with frequency, which is what may lead you to think that 250Hz provides the same results as 125Hz.
But, if you take some time to test it, you'll see that a 1000Hz physics engine allows a F1 car to break its suspension over a bump, while using 125Hz the F1 car *might* not even feel it, tunneling through it. (this example can be avoided using certain techniques in collision detection, or even variable timestepping, but serves for the example).
There are some attempts at continuum collision detection, you might want to check the Bullet library. I haven't tried it personally (other than a few demos), but it doesn't look bad.


Regarding the tire model, as you point out, simply using certain algorithms doesn't mean the simulation will be realistic. ISI sims are known to use pacejka-like tire models, but use very wrong data for certain slip angles (i dont' want to start a flame war, it's just the way it is), which makes the sim be less realistic at times (or always). After all, it's very hard/expensive to get data for tire models, so it's usually about guesstimating values all over the place. And of course, there's no way to check the resulting simulation is accurate. This is what makes car simulator creation a nightmare when you want to reach certain levels of realism :lol: .

As usual, sorry for the offtopics; maybe a couple thread forks are in order?