"Curtis L. Olson" <[EMAIL PROTECTED]> said:
> My one *big* caution on this is to *think* about and pay *attention*
> to opengl state management issues. If you don't have a good handle on
> the subtleties involved, you could make a real mess of things or
> introduce subtle rendering bugs.
>
Got it. Generally I'm pretty good at figuring out what something is and how it
impacts things before I change it...and shy away from the parts that I don't
have the time or ability to figure out. That said, mistakes can happen, but
I'll do my best keep this in order.
Speaking of impact, one thing that has been on my mind is what to do with the
location (aka position) data. Right now just about everything is either
asking the viewer for information or directly accessing the hard coded path to
the property tree ("/position/").
The immediate problem is the viewer doesn't always know the correct
information to give. Currently it is faking it to placate the routines that
are still asking the viewer for things like sea level vectors and "view
position". By "faking it", I mean it is calculating and reporting a "view
position" based on the location of the aircraft that might not actually be the
"real" current view position.
Well you might say, that it is ok for the "view position" to be reported by
the viewer. In some cases I think the values aren't being used in an expected
way. And keep in mind that the "actual" view position is no longer (as in
Tower view) anywhere near the aircraft that is being driven by the FDM.
These problems were evident during testing before I made the viewer fake the data:
1). Somehow the altitude in JSBSim was being increased to the height of the
tower. Thus when you went back to the pilot view the plane was falling from
the sky.
2). Depending on how the view positions are located, and where the tile
boundries are, switch views will trigger tile loading code.
Other problems:
Even with the data that I am faking, there still seems to be a problem with
the lights (both runway and "city" lighting).
1) It appears that when switching tiles the lights jump up.
2) From the tower view the runway lights are way to high.
Solutions?
Unless we want to maintain the tile cache for each view (ack!) then we should
have one location that has nothing to do with "view" for developing the cache.
The view positions, depending on how they are cofigured can either look at
the tile cache or not. As some have noticed you get a big-pale-blue-nothing
depending on how far away your tower is. This will be acceptable for the time
being, or we should print some sort of message that the view isn't going to be
displayed since it is too far away.
As far as the FDM is concerned, nothing from the viewer should be going to the
FDM, directly or indirectly.
Perhaps what we need to do is setup an "fdm location" or "master location"
that can be used as a reference for the construction of all the components in
the scene. The reason I'm bringing this up here in this thread is perhaps it
should be controlled in the FGScene class.
Best,
Jim
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