On Sat, 28 Aug 2004 17:34:47 -0500, David wrote in message 

> > We could also simulate the condense effect by this (when in right
> > combination of temerature and rel. humidity, water drops appear
> > behind the engine).
> That would be nice.  In the interim I'll have the contrail level
> default to 30000 feet, and make it user-settable in the startup
> configs.
> > Texture for this puff should be a bit more transparent, but 
> > should vary as well. 
> The trouble with transparent puffs is that they change transparency
> when they overlap.  Textured might work out better.  Here's a nice
> reference photo:
> http://www.airliners.net/open.file/638942/M/

..both can be done, textured in the normal case, and transplarant 
in the still rather rare case of FG formation flight.  ;-) 

> > It should last for more than 4 seconds as well and 
> > should slowly scale up (like the real condense lines when you look
> > at them from the ground).
> A 4-second trail looks like it has about 50 puffs in it (I'm
> guessing).  At some point there is a limit to how many AI objects you
> want at one time, but I don't know where that point is.  An 8 mile
> long contrail will take an airliner one minute to make, and that will
> require 750 puffs to build. I think we'll need a different system to
> build long contrails.
> As for the scaling, I don't know if that's possible.  Does Plib
> support scaling an object over time?

..a wild stab in the darkness: Does the clouds change in FG?

..a contrail is a cloud make by an engine (or more).  If it's damp
enough up there, contrails will grow into an overcast.  If it's dry,
contrails fade away, sometimes quickly, I've seen them form one 
plane length behind an airliner and gone in the next plane length.

..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.

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