Re: [Flightgear-devel] Bug reports... weather, and ILS...

[Stuart B. <stu...@ya...>]

Rob Shearman, Jr. wrote:
>Also, this has possibly been going on quite some time now (since I started reporting NaN bugs on my medium-haul flights), 
> but in many cases, the METAR doesn't change the active wind and cloud settings unless I actually look at the METAR
>  (Environment --> Weather Scenario).  As soon as I close the dialog box, the clouds change, the KIAS moves suddenly, 
> and the plane may rock side-to-side gently for a moment or two.  *RARELY* I will notice the weather settings change 
> on their own during flight, but it seems as if *USUALLY* it doesn't do so unless I look at the METAR.

In v1.0.0, there was a strange connection between the weather scenario and --enable-real-weather-fetch that didn't make
much sense - if you enabled real-weather-fetch it over-rode what you might set in the Weather Scenario dialog.

In v1.9.0, they are separated, so you must have the weather scenario set to METAR for real-weather-fetch to work
and be updated by subsequent METAR updates.

So, if you're not seeing any METAR updates, check that you've set the scenario correctly.

Two further possible sources of confusion:
1) I'm sure you are aware of the weather interpolation that takes place when a new METAR is received - the wind will change
fairly slowly to the new value, so under normal circumstances, you shouldn't really notice the new METAR as a distinct change
in the environment.
2) We hit a found a very late bug in the cloud code due to METAR interpolation. I can't remember the details (have a look in
the mail archive), but IIRC I ended up disabling some of the 3D cloud updates. This was subsequently fixed in CVS.

When you close the Weather Scenario dialog, instead of interpolating to the new weather values, the environment is rebuilt
from scratch based on the selected scenario. This may cause an immediate wind change (which the aircraft has to react to)
and/or cloud changes.

As an aside, at some point I'd like to enhance the weather scenario code to allow arbritary environmental config to be saved/loaded
so we can provide a bunch of different scenarios.

Hope this casts some light on what might be going on. It is of course, entirely possible that there are some bugs there too!

-Stuart