[Flightgear-devel] Current Elevation
I want to get the elevation of the ground for points other than my current location. I suppose I could do this by moving to a new location and calling scenery.get_cur_elev(). Is there a better way? If not, what operations will update the output of FGScenery::get_cur_elev() in the most efficient way? ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Current Elevation
Sam Varner [EMAIL PROTECTED] said: I want to get the elevation of the ground for points other than my current location. I suppose I could do this by moving to a new location and calling scenery.get_cur_elev(). Is there a better way? If not, what operations will update the output of FGScenery::get_cur_elev() in the most efficient way? That's actually a problem that I'm working on currently. If you look at tilemgr.cxx, the update() function you'll see where the value for current elevation gets set. What you can do is modify that function to accept an absolute view position vector along with the longitude and latitude paramters and pass it along to the hitlist fgCurrentElev call. Take a look at location.cxx to see how that absolute position vector is calculated (it is actually based on the latitude and longitude with the altitude integraded to give you coordinates in 3D space). Calling the update() routine in this way causes some trouble with the tile caching because the caching is based on distance from the longitude and latitude you specify. When the routine was written we were dealing with a single view location and an a longitude and latitude that changed gradually, not abruptly. If you keep jumping that around the tile cache starts thrashing a bit (unless the locations are reasonably close to each other). All this said, calling update() will give you the readings you are looking for. Just make sure that the current elevation gets set right back to whatever is correct for the aircraft (the value returned by scenery-get_cur_elev()), otherwise you'll see some other issues come up. Sometime in the next week or so look for updates to this code that will make what you want to do a little easier and fix the numerous bugs in the scenery and sky rendering that have come up since the new viewer code was introduced. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Current Elevation
On Thu, 2002-05-02 at 20:14, Jim Wilson wrote: Sam Varner [EMAIL PROTECTED] said: I want to get the elevation of the ground for points other than my current location. I suppose I could do this by moving to a new location and calling scenery.get_cur_elev(). Is there a better way? If not, what operations will update the output of FGScenery::get_cur_elev() in the most efficient way? That's actually a problem that I'm working on currently. If you look at tilemgr.cxx, the update() function you'll see where the value for current elevation gets set. What you can do is modify that function to accept an absolute view position vector along with the longitude and latitude paramters and pass it along to the hitlist fgCurrentElev call. Take a look at location.cxx to see how that absolute position vector is calculated (it is actually based on the latitude and longitude with the altitude integraded to give you coordinates in 3D space). Calling the update() routine in this way causes some trouble with the tile caching because the caching is based on distance from the longitude and latitude you specify. When the routine was written we were dealing with a single view location and an a longitude and latitude that changed gradually, not abruptly. If you keep jumping that around the tile cache starts thrashing a bit (unless the locations are reasonably close to each other). All this said, calling update() will give you the readings you are looking for. Just make sure that the current elevation gets set right back to whatever is correct for the aircraft (the value returned by scenery-get_cur_elev()), otherwise you'll see some other issues come up. Sometime in the next week or so look for updates to this code that will make what you want to do a little easier and fix the numerous bugs in the scenery and sky rendering that have come up since the new viewer code was introduced. I'll be more explicit about what I'm trying to do, and you can tell me if you want to change your answer:) I'm working on a car model; the elevations I want are the elevations under each tire. The points will be close together, so there shouldn't be any tile cache probelms, but I'll have to do the calculation for each tire (and any other point on the car that could come into contact with the ground) every time step. Also, I don't want the point-of-view to change as I'm checking each potential contact point. Is update() still the way to go? Thanks. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Current Elevation
Sam Varner [EMAIL PROTECTED] said: On Thu, 2002-05-02 at 20:14, Jim Wilson wrote: Sam Varner [EMAIL PROTECTED] said: I want to get the elevation of the ground for points other than my current location. I suppose I could do this by moving to a new location and calling scenery.get_cur_elev(). Is there a better way? If not, what operations will update the output of FGScenery::get_cur_elev() in the most efficient way? That's actually a problem that I'm working on currently. If you look at tilemgr.cxx, the update() function you'll see where the value for current elevation gets set. What you can do is modify that function to accept an absolute view position vector along with the longitude and latitude paramters and pass it along to the hitlist fgCurrentElev call. Take a look at location.cxx to see how that absolute position vector is calculated (it is actually based on the latitude and longitude with the altitude integraded to give you coordinates in 3D space). Calling the update() routine in this way causes some trouble with the tile caching because the caching is based on distance from the longitude and latitude you specify. When the routine was written we were dealing with a single view location and an a longitude and latitude that changed gradually, not abruptly. If you keep jumping that around the tile cache starts thrashing a bit (unless the locations are reasonably close to each other). All this said, calling update() will give you the readings you are looking for. Just make sure that the current elevation gets set right back to whatever is correct for the aircraft (the value returned by scenery-get_cur_elev()), otherwise you'll see some other issues come up. Sometime in the next week or so look for updates to this code that will make what you want to do a little easier and fix the numerous bugs in the scenery and sky rendering that have come up since the new viewer code was introduced. I'll be more explicit about what I'm trying to do, and you can tell me if you want to change your answer:) I'm working on a car model; the elevations I want are the elevations under each tire. The points will be close together, so there shouldn't be any tile cache probelms, but I'll have to do the calculation for each tire (and any other point on the car that could come into contact with the ground) every time step. Also, I don't want the point-of-view to change as I'm checking each potential contact point. Is update() still the way to go? Thanks. Yes, I think it is. Just make another version of it for this purpose. Use update() to update your car's origin and trigger the tile loads. Make another one that's basically the same as update(), minus the tile loader scheduling (the middle part of the routine) and just have it return the elevation. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
