Fr/A local weather system: Difference between revisions

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* [http://www.flightgear.org/forums/viewtopic.php?f=5&t=8365 Weather algorithms] (06/2010)
* [http://forum.flightgear.org/viewtopic.php?f=5&t=8365 Weather algorithms] (06/2010)
* [http://www.flightgear.org/forums/viewtopic.php?f=5&t=8137 A smart cloud altitude algorithm] (05/2010)
* [http://forum.flightgear.org/viewtopic.php?f=5&t=8137 A smart cloud altitude algorithm] (05/2010)
* [http://www.flightgear.org/forums/viewtopic.php?f=5&t=7591 Weather dynamics] (04/2010)
* [http://forum.flightgear.org/viewtopic.php?f=5&t=7591 Weather dynamics] (04/2010)
* [http://flightgear.org/forums/viewtopic.php?f=5&t=6968 New thunderstorm AI scenario alpha release] (02/2010)
* [http://flightgear.org/forums/viewtopic.php?f=5&t=6968 New thunderstorm AI scenario alpha release] (02/2010)
* [http://flightgear.org/forums/viewtopic.php?f=5&t=7107 Cirrus sky (download link in first post)] (02/2010)
* [http://flightgear.org/forums/viewtopic.php?f=5&t=7107 Cirrus sky (download link in first post)] (02/2010)
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== Les demandes de fonctionnalités du côté C++ ==
== Les demandes de fonctionnalités du côté C++ ==


Intended as a base for discussions on how to implement particular features in the C++ code. Also see [http://www.flightgear.org/forums/viewtopic.php?f=5&t=8365 Weather algorithms discussion] from 06/2010.
Intended as a base for discussions on how to implement particular features in the C++ code. Also see [http://forum.flightgear.org/viewtopic.php?f=5&t=8365 Weather algorithms discussion] from 06/2010.


As of version 0.81, the local weather system runs on a high-end system, but has problems on slower machines and could use performance boosts from implementing some features which currently are done from Nasal in C++. Guiding principles for that should be '''performance''', '''accessibility''', a '''clear structure''' and '''backward compatibility'''. The decision if a particular function should be implemented on the C++ level should be investigated with these in mind - usually performance is served better from C++, but Nasal structures remain more accessible. For example, cloud configurations (assembling a vector of coordinates where to place clouds) can usually be done in Nasal in a single frame and thus the performance boost when porting to C++ is marginal. On the other hand, cloud configurations are crated by functions which turn a set of parameters into cloud positions, and it is useful to have quick access to the parameters and functions to tune the system to reproduce a real sky better and better without the need to recompile the code. Thus, cloud configuration computations are an example for structures which should probably not be ported to C++.
As of version 0.81, the local weather system runs on a high-end system, but has problems on slower machines and could use performance boosts from implementing some features which currently are done from Nasal in C++. Guiding principles for that should be '''performance''', '''accessibility''', a '''clear structure''' and '''backward compatibility'''. The decision if a particular function should be implemented on the C++ level should be investigated with these in mind - usually performance is served better from C++, but Nasal structures remain more accessible. For example, cloud configurations (assembling a vector of coordinates where to place clouds) can usually be done in Nasal in a single frame and thus the performance boost when porting to C++ is marginal. On the other hand, cloud configurations are crated by functions which turn a set of parameters into cloud positions, and it is useful to have quick access to the parameters and functions to tune the system to reproduce a real sky better and better without the need to recompile the code. Thus, cloud configuration computations are an example for structures which should probably not be ported to C++.
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* (06/2012) Sun is always painted on top of the skydome, you even see it through what is supposed to be terrain from high altitude. That's an issue for the maintainer of the sun code, it isn't curable via Nasal. See [https://code.google.com/p/flightgear-bugs/issues/detail?id=788&sort=-id&colspec=ID%20Type%20Status%20Priority%20Summary%20Aircraft%20Milestone].
* (06/2012) Sun is always painted on top of the skydome, you even see it through what is supposed to be terrain from high altitude. That's an issue for the maintainer of the sun code, it isn't curable via Nasal. See [https://code.google.com/p/flightgear-bugs/issues/detail?id=788&sort=-id&colspec=ID%20Type%20Status%20Priority%20Summary%20Aircraft%20Milestone].


* expose the atmospheric model to the property tree (or Nasal) [http://www.flightgear.org/forums/viewtopic.php?f=30&t=8743#p86387] [http://www.flightgear.org/forums/viewtopic.php?f=5&t=7358&st=0&sk=t&sd=a&start=15#p70714] [http://www.av8n.com/fly/fgfs/README.altimetry.html] [http://www.av8n.com/physics/altimetry.htm]
* expose the atmospheric model to the property tree (or Nasal) [http://forum.flightgear.org/viewtopic.php?f=30&t=8743#p86387] [http://forum.flightgear.org/viewtopic.php?f=5&t=7358&st=0&sk=t&sd=a&start=15#p70714] [http://www.av8n.com/fly/fgfs/README.altimetry.html] [http://www.av8n.com/physics/altimetry.htm]


* Once I cross the mountaintops, some system switches on turbulence (I suspect ridge lift, since I could not find any other property which would create turbulence). That's bad, because wave lift isn't turbulent at all. To disable the ridge lift system, set '''/environment/ridge-lift/enabled''' to 0
* Once I cross the mountaintops, some system switches on turbulence (I suspect ridge lift, since I could not find any other property which would create turbulence). That's bad, because wave lift isn't turbulent at all. To disable the ridge lift system, set '''/environment/ridge-lift/enabled''' to 0

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