[ODE] Client prediction and asynchronous simulation

[Jon Watte (ODE)]

You do not have to run physics at the same rate as rendering on the 
client. You can use interpolation between physics frames on the client, 
when rendering multiple sub-steps.

Cheers,

          / h+


Eric Lasota wrote:
> I'm in the planning phases of a multiplayer FPS which is going to have 
> vehicles.  The main issue is that the server operates at a fixed 
> framerate (usually 30Hz), but clients operate at a different framerate 
> (usually 125Hz), and their updates aren't synchronized with the rest of 
> the world.  Disabling prediction and forcing syncing is an option, but 
> going off of some descriptions of similar attempts (i.e. vehicles in 
> Garry's Mod), that sounds extremely unresponsive.
>
> The current solution I'm looking at would basically have all interactive 
> objects disabled (including other players) during client simulation, and 
> clients disabled during the simulation of everything else.
>
> My main concern is overpenetration or repeated collision into objects 
> if, for example, a vehicle rams something and pushes it, or rear-ends 
> someone, maintaining its current direction towards the object, but the 
> client has another update scheduled before the object it pushed does.  
> Would it be possible to, for example, make bodies completely immovable 
> temporarily (preventing penetration into them for more than one step) 
> instead of simply disabling them, and handle force accumulation separately?
>
> The only major artifact I can think of from such a method would be hard 
> stops from relative collision (i.e. rear-end someone going slightly 
> faster than you and you'll wind up coming to a dead stop), which is 
> acceptable.
>
> Another concern is whether or not there any implications to a body being 
> disabled for more than one consecutive step.
>
> Any thoughts?
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