[Flightgear-devel] Volcanoes - an update

[Thorsten R. <tho...@sc...>]

I think I've now made a set of design decisions which hopefully will make  
everyone happy:

* volcanoes are managed neither by the AI system nor the scenemodels but a  
new Nasal volcano manager

* the manager is an opt-in system that needs to be activated to run

* what it does is maintain a list of how distant to the plane implemented  
volcanoes are. Based on that list, it switches any particular volcano  
model on if the volcano is closer than 150 km and in visible range  
(whatever happens first). The advantage is that models (and particle  
systems) loaded that way are visible from afar, which is somewhat  
important for lava fountains a few hundred meters high or ash plumes.

* any implemented volcano has the option to utilize its own Nasal code  
that is loaded 'on demand' along with the 3d model (for instance, to time  
and regulate eruption plumes) - most of the volcano code will therefore be  
neither run nor loaded during a normal FG session

* what it will do in the future is talk to the weather system to render  
the ash clouds downwind - I'll probably have to extend the precipitation  
code to simulate ash fall - in any case the weather system will provide  
the property in case anyone is interested in simulating engine damage

Hope that's all acceptable to everyone.

Right now I have worked my way up to Stromboli-type eruptions which are  
somewhat more violent than the Hawaiian ones.

https://forum.flightgear.org/viewtopic.php?f=19&t=32982

Looking at some footage of the Pinatubo eruption, super-Plinian events  
might be a toughie - we're talking an ash column > 40 km high for  
instance, so this would be felt and seen from hundreds of kilometers away.

Oh - I guess if ever we want to provide a generic environment sound  
option, that might be a good use case. I'm guessing if you're close  
enough, you can hear a volcano quite well even over the engine noise...

* Thorsten