RE: [certi-dev] FlightGear simulation latency

[Gotthard, Petr]

Hi Eric,

> Some more FlightGear for dummy question,
> Why should the VirtualAir plugin call
> 
> set_hz()
> 
> Is FlightGear supposed to call some function
> (process_i?) of the plugin periodically?

Yes. It's similar to the HLA tick() function. The FlightGear simulation
engine is based on regularly invoked "models". (Many functions in
FlightGear are models, including input/output.) Each model has a "Run"
method that is invoked with a given frequency.

> If it is the case why should FilghGear do that kind of thing
> periodically?
> Won't it be easier to do it asynchroneously, "when necessary"?
> I thought it was the purpose of the dead reckoning to do such thing,
> am I wrong?

The model scheduler is very low-level and based only on the frequency.
In the "Run" method, each model may do some checks and "when necessary"
perform an action.

In fact, set_hz() defines only how often is the "Run" method invoked. It
does not say how often is an action performed, or how often input/output
sends/receives data.


Petr