Re: [Flightgear-devel] High altitute/speed flights terrain engine problems

[<tho...@jy...>]

> If two users in parallel flying spacecrafts will see the same good then
> there is no problem. But everything on Nasal is on local level, not
> global core level.

At least one of us is confused about how things are structured.

My understanding is that there's nothing in Flightgear which guarantees
that two users flying parallel get to see the same. My understanding of
the multiplayer protocol is that it largely exchanges position information
of models and submodels, in addition to model and livery path.

If we're flying over Seattle, and you have the default scenery and I the
Pacific Northwest custom scenery, I will see different terrain than you
do. If I don't have your aircraft model installed, then I will see a
placeholder (I think a funny-coloured glider) at your position. If I'm
running live weather and you have 'Fair Weather' selected, I might have
few hundred meters visibility and rain whereas you fly next to me in
bright sunshine.

Similarly, I don't see how you could guarantee that two spacecraft users
see the same, unless they have the same models/textures/scripts for
rendering Earth from high altitude installed.

I have no idea what you mean by the distinction of Nasal being on a local
level and the core on a global level. If you look into /Nasal/, you find
scripts like multiplayer.nas, tanker.nas or redout.nas which are available
whatever aircraft you have installed or whatever aircraft you are in -
just as the core, they are part of every Flightgear session.

But, see above, neither core nor scripts are ever global in the sense that
they'd be the same for every user - if you run GIT and I run 2.0.0, the
core is obviously not the same.

>> Scenery models usually exist on the whole FG level...
>
> Earth is not scenery.

Well, that's precisely my point, isn't it? You don't need a new terrain
engine if you stop thinking about planets from high above as 'terrain'. 
>From a Celestia perspective, Earth is just a sphere with a very high
resolution texture and reflection and normalmap shaders. That's something
Flightgear has the functionality to render without much ado or additional
coding - as a scenery model.

So if, for spaceflight, you write a /Nasal/earthview.nas which
periodically checks altitude and loads a large enough scenery model above
40 km while it de-activates the default terrain, you have solved the
problem of implementing Celestia-like views of Earth in Flightgear.

> So if choice is between redoing things what's already done and including
> that things I would prefer including. There is four or five Open Source
> space simulators and most of them is not so addable for modder or even
> usable for end user. If them authors could put their efforts together
> then we could have best space sim already.

If that would happen, it would be very nice. It also would be nice if
people would send me their GPL-compatible photographs of Cb clouds so that
I could improve my thunderstorm textures which are rather lousy at the
moment. It would also be nice if people would pool their resources to
create a nice GPL-compatible database of aerial images so that we'd have
raw material for texturing.

All that doesn't just seem to happen... so I have to make do with what
happens. It's a bit up to you - if you can get off a demo of a nice Earth
view from space using existing technology, the likelihood of getting more
people interested in working on the issue increases. If you wait for the
best solution to be implemented up front, you may be lucky, but it also
may be a long wait.

Cheers,

* Thorsten