Re: [Algorithms] Network prediction algorithms specific to racing?

[Jason H. <jh...@st...>]

I guess there are two aspects of this: prediction and visual rectification.

We've been doing a networked basketball game recently, where one team is 
entirely controlled remotely.  Even with fairly high latency, slow 
moving objects (like players) will look okay using a smooth 
rectification algorithm, but they're a little delayed from real-time.  
High velocity objects  (ie. bullets or ballistic objects) are pretty 
easy to sync as well, provided they are not controlled or intelligent.  
The main issues we've had thus far involve rectifying the ball physical 
state after a collision with a player, since that's often incorrect and 
delayed.  Luckily, most collisions in basketball games result in the 
ball being grabbed, so this isn't always an issue.  For reference, our 
simple rectification code is X = Lerp(X, X', f), where f could vary 
depending on the latency and current error.  Spline rectification would 
be nicer, and we might implement that, though it may be overkill for us.

I haven't tried prediction beyond simple linear extrapolation based on 
the last single sample (position, velocity, orientation).  1st order 
prediction would likely close most of the gaps for generally smooth 
functions like position and orientation, but for velocity, I'm not sure 
it would help in our case, since the velocity is basically joystick 
angle for us and is generally discontinuous.

Sorry I can't be more help with racing specifically.  Out of curiosity, 
what have you tried and how did it work?

Thanks,
JH

Jason Hughes
President
Steel Penny Games, Inc.
Austin, TX


On 4/15/2010 3:34 PM, Megan Fox wrote:
> I'm currently fiddling with dead reckoning for a racing game I'm
> working on, but this seems like a specific enough domain that there
> ought to be specific-to-racing prediction approaches.  We have a
> fairly good idea of what the player is doing (trying to stay on the
> track), and that would seem to give more data that isn't really being
> exploited with standard approaches - but googling isn't turning up
> much.
>
> Do such algorithms exist?  Or, in practice, are the same approaches
> used in FPSes et al still the ones to use here?
>
>