David Megginson writes: > I would like to make it possible to specify the elevation of static > and shared objects AGL as well as ASL, but for that, I need to know > the elevation ASL at a specific location (not the current view > position). I have taken a look at the fgCurrentElev() functions in > hitlist.cxx and (I think) supplied the right parameters, but I'm > getting no intersection. > > The problem location is tileentry.cxx -- search for "OBJECT_STATIC" to > find the right chunk of code. Somehow, there, I want to be able to > determine what ground elevation is at the lon/lat supplied.
Norman Vine is the architect of the ground intersection code and it is sufficiently complicated that probably no one else has dug in and tried to understand it ... it's also heavily optimized which is good for fps, but bad for anyone else trying to grok it. FWIW, it would be handy to have a general intersection API so you could specify any vector and get back the intersection points with terrain. This would allow you to test if you have line of sight with a navaid, test if you one chunk of terrain is shading another, might be useful for some sort of ground collision avoidance system, etc. It would also be nice to do interesections at tile load time so when you specify objects in the .stg file, you can just give them a lat/lon and let the system position them correclty on the ground surface. Curt. -- Curtis Olson IVLab / HumanFIRST Program FlightGear Project Twin Cities [EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
