... and yet another issue:
On a first long-range test yesterday, I observed that the cloud base of my
convective layer was continuously rising. At takeoff the clouds were
exactly as specified, later still plausible given terrain, but by the time
the cloudbase had reached my curise altitude of 20.000 ft, I was
reasonably certain that this had nothing to do with realistic terrain
interaction and must be a bug.
Convective cloud altitude determination is quite a complex procedure, and
I spent 30 minutes to go through all of it. In the end, I verified that
the raw list of alt-ft property values passed to fgcommand("add-cloud",
p); is what it should be (in the 8000 ft range) by printing the whole set
of 500 values to the console and that
/environment/clouds/layer[0]/elevation-ft is set to zero (so that I can
compute the absolute altitude of clouds in my routines) while clouds are
drawn at 20.000 ft (I have a screenshot of that if needed).
My only remaining theory is that /environment/clouds/layer[0]/elevation-ft
describes a layer in Cartesian geometry which is attached to the sphere at
my startup point. As I fly long distances, the spherical Earth curves away
below the flat, uncurved layer, and thus there is an ever-increasing
mismatch between zero altitude in (lat,lon,alt) coordinates on the sphere
and zero altitude on the layer. This would at least be consistent with
what I'm seeing.
If so, there probably needs to be a routine which matches Cartesian and
spherical geometry periodically... if not, I simply don't know what is
wrong.
* Thorsten
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