Re: [Flightgear-devel] YASIM/Viewer mismatch
On Thu, 4 Apr 2002 15:17:23 -, "Jim Wilson" <[EMAIL PROTECTED]> wrote in message <[EMAIL PROTECTED]>: > David Megginson <[EMAIL PROTECTED]> said: > > > Jim Wilson writes: > > > > > Err umm...what is it that won't be necessary? > > > > Using properties other than the /position ones. > > > > Right from the start I've been planning to support that anyway. > > Two reasons: > 1) Probably soon to be realized multiple instances of FDM and models. .. ;-) > 2) Towers don't fly (usually). So their position and orientation > needs to come from elsewhere. ..chase cars, chasing balloons??? Choppers, autos and/or boats, with rc-pilot onboard crossing the Channel, Pond, Pasific etc etc... ..tried it, wound up in the drink, with honors, on T/O off a quay, a frozen wheel bearing. ;-) Idea was, set a distance record and land at site of the Northern Norw. Championship. ;-) Next T/O, there, needed a wee pirouette to lift wheel with said bearing, a fuel tank pickup tube not on todo-list, forced a silent wingover, premature hot final over hot lines, to take advantage of said bearing to maximize needed landing point score, silenced annoying awed event speaker, and city, in sparkling glory. ;-) ..morale; investigate first, then repair, sleep and preflight, improvisation and man, has a few, but firmly proven limitations. ;-) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
David Megginson writes: > Andy Ross writes: > > > I'll chop the cockpit stuff out of YASim as soon as someone tells me > > it's OK. > > It's fine with me. Curt? Sure, sounds good to me. 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
Re: [Flightgear-devel] YASIM/Viewer mismatch
David Megginson <[EMAIL PROTECTED]> said: > Jim Wilson writes: > > > Err umm...what is it that won't be necessary? > > Using properties other than the /position ones. > Right from the start I've been planning to support that anyway. Two reasons: 1) Probably soon to be realized multiple instances of FDM and models. 2) Towers don't fly (usually). So their position and orientation needs to come from elsewhere. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson writes: > Err umm...what is it that won't be necessary? Using properties other than the /position ones. All the best, David -- David Megginson [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
David Megginson <[EMAIL PROTECTED]> said: > Jim Wilson writes: > > > Ok, I think this means I can continue in the same direction with > > the viewer code. It would be just a matter of editing xml to > > switch from using /position/lat||lon||alt to somewhere else in the > > property tree, so if folks want to experiment they can. > > I don't know if that will be necessary. As long as we agree that the > lat/lon/alt give a fixed position (somewhere) on the plane, that's > good enough, and it becomes a convention to be agreed upon model by > model. I agree with Jon that when the manufacturer does specify an > origin, we should use that. > Err umm...what is it that won't be necessary? Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Arnt Karlsen writes: > ..a wee point: in sideslipping, will the responsible pilot > stare, towards the infinte end of the longitudal axis, or will > he watch/look out to where he is going? My .02, only. ;-) We are talking only about the default viewpoint location. It's up to the pilot to control the view orientation using the mouse, keyboard, joystick hat, etc. All the best, David -- David Megginson [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Andy Ross writes: > I'll chop the cockpit stuff out of YASim as soon as someone tells me > it's OK. It's fine with me. Curt? All the best, David -- David Megginson [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson writes: > Ok, I think this means I can continue in the same direction with > the viewer code. It would be just a matter of editing xml to > switch from using /position/lat||lon||alt to somewhere else in the > property tree, so if folks want to experiment they can. I don't know if that will be necessary. As long as we agree that the lat/lon/alt give a fixed position (somewhere) on the plane, that's good enough, and it becomes a convention to be agreed upon model by model. I agree with Jon that when the manufacturer does specify an origin, we should use that. All the best, David -- David Megginson [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson writes: > >As far as the viewer.cxx and model.cxx code are concerned the axes for >orientation rotations will continue to be at the model origin >(which is set at >the lon/lat/alt reported by FDMs) until further notice :-) Ah... the CG :-) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] YASIM/Viewer mismatch
> Ack, really? I was honestly under the impression that you were > handing out the coordinate frame too; I thought I had checked this in > code when writing YASim. Perhaps this is related to the misunderstanding of our gear model and how we determined where we were? > Why c.g.? Since it moves, it forces the > model renderer to track the current value and do an extra translation. When we wrote the code for this initially, and for years afterwards, there *was* no model renderer. :-) In hindsight, I realize we may have erred in this. I'll add that initially we didn't model moving the CG around either, so it wasn't a big deal. I'll repeat points 3 and 4 I made earlier: 3) The turn coordinator instrument (to my knowledge) works in consideration of where it is located, typically right in front of the pilot. The accels sensed by this instrument include rotational effects at the pilots moment arm _from_the_current_CG_. 4) If FlightGear was ever to be hooked up to a motion base, the motion of the base might be linked to the second derivative of the body velocities _at_the_pilot_location_ relative to _the _current_CG_. Thus, again in this case and with point #3, above, the flight model still needs to know where the pilot is. I still recommend that the FDM be allowed to at least _recommend_ a pilot eyepoint, as some calculations inside the FDMs will use this value. It would be nice if this value could be useful to FlightGear. FlightGear could still be allowed to shift the viewpoint as it wished, but with the understanding of points 1 - 4, above. In any case, to the best of my recollection, this is how LaRCSim does it, how McFarland's paper describes it, etc. This is how to do it naturally. It may be that we should take it a step further and extrapolate the "reference point" from that, whatever that should be, and report the lat/lon/alt (henceforth known as LLA). Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Andy Ross <[EMAIL PROTECTED]> said: > Jim Wilson wrote: > > Ok, so are you saying that the lon/lat/alt values that the fdm outputs > > are at the origin already adjusted for cg? If so then how would that > > affect the axis of say pitch rotation on the c172 model? It's origin > > is at the firewall and the pitch rotation is always on the access that > > intersects there. Should we be doing something different? > > The second answer, if I understand the question, is "it doesn't > matter". Orientations and positions have nothing to do with each > other. The lat/lon/alt values tell you where the firewall point of > the aircraft is, but they don't say anything about where the aircraft > is pointing. The hdg/pitch/roll numbers tell you how the aircraft is > oriented, but not where the firewall is. Sorry, I mistyped that message. What I was concerned about was the "axis" of rotation. Where the aircraft pivots when the pitch angle changes similar to where the fulcrum would be if the aircraft was a seesaw. It probably doesn't change all that much (for visualization) and I'm not going to worry about it right now. As far as the viewer.cxx and model.cxx code are concerned the axes for orientation rotations will continue to be at the model origin (which is set at the lon/lat/alt reported by FDMs) until further notice :-) Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Curtis L. Olson wrote: > Here's what make sense to me. > > The FDM defines some aribitrary reference point (i.e. on the firewall) > and provides the lon/lat/elev of that point. > > The FDM really doesn't care about the actual FlightGear view point. > It won't know if the user is flying from the left seat, the right > seat, or seat 5A in the DC-3. Yeah, I've changed my mind; I agree with you. The only sane place to put the responsibility for the view point is in the model description. It's all well and good for the FDM to know where the cockpit it, but that won't do us any good when it goofs by as little as 50cm and the pilot can't see over the panel. :) I'll chop the cockpit stuff out of YASim as soon as someone tells me it's OK. Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com "Men go crazy in conflagrations. They only get better one by one." - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jon S. Berndt wrote: > Jim Wilson wrote: > > Ok, so are you saying that the lon/lat/alt values that the fdm > > outputs are at the origin already adjusted for cg? > > JSBSim gives the lat/lon/alt of the CURRENT CG - NOT the origin of the > structural frame. Ack, really? I was honestly under the impression that you were handing out the coordinate frame too; I thought I had checked this in code when writing YASim. Why c.g.? Since it moves, it forces the model renderer to track the current value and do an extra translation. Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com "Men go crazy in conflagrations. They only get better one by one." - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson wrote: > Ok, so are you saying that the lon/lat/alt values that the fdm outputs > are at the origin already adjusted for cg? If so then how would that > affect the axis of say pitch rotation on the c172 model? It's origin > is at the firewall and the pitch rotation is always on the access that > intersects there. Should we be doing something different? OK, now I'm confused. :) To the first part: yes. If you take an aircraft with zero velocity and spin it, the output lat/lon/alt values from the FDM will be moving in a circle around the center of gravity, even though the c.g. is stationary. All of this math is done for you by the FDM. The second answer, if I understand the question, is "it doesn't matter". Orientations and positions have nothing to do with each other. The lat/lon/alt values tell you where the firewall point of the aircraft is, but they don't say anything about where the aircraft is pointing. The hdg/pitch/roll numbers tell you how the aircraft is oriented, but not where the firewall is. Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com "Men go crazy in conflagrations. They only get better one by one." - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
On Wed, 3 Apr 2002 17:16:31 -0500, David Megginson <[EMAIL PROTECTED]> wrote in message <[EMAIL PROTECTED]>: > Jon S Berndt writes: > > > I'm not sure I understand what you are saying, here. I will say, > > however, that if there is a viewpoint given for pilot eyepoint in a > > JSBSim config file it would be good to reference it somehow (even > > if you copy it into an aircraft 3d model file) because it will be > > accurate information for the *pilot* eyepoint, if nothing else. > > At least it would be close. I'm sure that the eyepoints are different > for a 5'2" pilot and a 6'4" pilot, and we also want to be able to > model leaning forward, etc. ..a wee point: in sideslipping, will the responsible pilot stare, towards the infinte end of the longitudal axis, or will he watch/look out to where he is going? My .02, only. ;-) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson writes: > >Jon S Berndt <[EMAIL PROTECTED]> said: > >> On Wed, 3 Apr 2002 18:44:23 -0500 >> "Norman Vine" <[EMAIL PROTECTED]> wrote: >> >> >My take on this is that all we need is a 'fixed' position ie 'Center of >> >Geometry' returned by the FDM. This fixed position can be anywhere >> >on the AirFrame and it needs to be described more exactly in the >> >individual model's configuration >> >file so as the Viewer part of the program can do it's thing >> >> Yeah, I think that's where we're headed. > >> However, when reporting location (lat/lon/alt) we'd >> need to report NOT merely the location of the current >> aircraft CG, but the location of the current aircraft CG >> minus the delta from the original - i.e. the location of >> the original CG. (?) >> > >Ok, I think this means I can continue in the same direction with the viewer >code. It would be just a matter of editing xml to switch from using >/position/lat||lon||alt to somewhere else in the property tree, so if folks >want to experiment they can. As for the xyz viewer eyepoint offsets, those >will be in the /sim/view[x] tree(s) and can be set with aircraft-set.xml or >whatever else. Right The Viewer Code HAS to assume that the position reported by the FDM is invariant with respect to the airframe or else the Viewer really is 'lost' So I would just carry on assuming this to be the case and hopefully the rest will get sorted out shortly. Cheers Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jon S Berndt <[EMAIL PROTECTED]> said: > On Wed, 3 Apr 2002 18:44:23 -0500 > "Norman Vine" <[EMAIL PROTECTED]> wrote: > > >My take on this is that all we need is a 'fixed' position ie 'Center of > >Geometry' returned by the FDM. This fixed position can be anywhere > >on the AirFrame and it needs to be described more exactly in the > >individual model's configuration > >file so as the Viewer part of the program can do it's thing > > Yeah, I think that's where we're headed. It might work > that we could keep doing things as we (JSBSim) are doing, > with an added step. The initial CG of the aircraft could > be defined to be the refernce point that we both > understand. We would continue to "burn fuel" and drop > stores and launch carried vehicles, etc. and change the > CG. However, when reporting location (lat/lon/alt) we'd > need to report NOT merely the location of the current > aircraft CG, but the location of the current aircraft CG > minus the delta from the original - i.e. the location of > the original CG. (?) > Ok, I think this means I can continue in the same direction with the viewer code. It would be just a matter of editing xml to switch from using /position/lat||lon||alt to somewhere else in the property tree, so if folks want to experiment they can. As for the xyz viewer eyepoint offsets, those will be in the /sim/view[x] tree(s) and can be set with aircraft-set.xml or whatever else. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] YASIM/Viewer mismatch
Jon S Berndt writes: > "Norman Vine" <[EMAIL PROTECTED]> wrote: > >>My take on this is that all we need is a 'fixed' position ie 'Center of >>Geometry' returned by the FDM. This fixed position can be anywhere >>on the AirFrame and it needs to be described more exactly in the >>individual model's configuration >>file so as the Viewer part of the program can do it's thing > >Yeah, I think that's where we're headed. It might work >that we could keep doing things as we (JSBSim) are doing, >with an added step. The initial CG of the aircraft could >be defined to be the refernce point that we both >understand. We would continue to "burn fuel" and drop >stores and launch carried vehicles, etc. and change the >CG. However, when reporting location (lat/lon/alt) we'd >need to report NOT merely the location of the current >aircraft CG, but the location of the current aircraft CG >minus the delta from the original - i.e. the location of >the original CG. (?) > >Is that right? That should work with one more assuumption that the reference CG is consistant with all invocations of the program. ie initial CG is the 'dry condition' would work FWIW - The thing I am worried about here is that the CG at initialization time is dependent on many things and this may or may not be consistant. Therefore 'dry condition' is the 'empty plane' as represented in the manufacturer's specs Ciao Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
On Wed, 3 Apr 2002 18:44:23 -0500 "Norman Vine" <[EMAIL PROTECTED]> wrote: >My take on this is that all we need is a 'fixed' position ie 'Center of >Geometry' returned by the FDM. This fixed position can be anywhere >on the AirFrame and it needs to be described more exactly in the >individual model's configuration >file so as the Viewer part of the program can do it's thing Yeah, I think that's where we're headed. It might work that we could keep doing things as we (JSBSim) are doing, with an added step. The initial CG of the aircraft could be defined to be the refernce point that we both understand. We would continue to "burn fuel" and drop stores and launch carried vehicles, etc. and change the CG. However, when reporting location (lat/lon/alt) we'd need to report NOT merely the location of the current aircraft CG, but the location of the current aircraft CG minus the delta from the original - i.e. the location of the original CG. (?) Is that right? Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
On Wed, 3 Apr 2002 17:29:42 -0600 (CST) "Curtis L. Olson" <[EMAIL PROTECTED]> wrote: >Jon S Berndt writes: >I think this boils down to let's have the FDM worry about where the >plane is, and let's have FlightGear worry about where the current view >point is. I agree. We don't care about where the view is. Just remember the four points I made in the earlier email (particularly #3 and #4). We will be supplying a pilot position in the aircraft config file for weight and balance and sensed accelerations purposes. I'll be happy that the view is not merely at the CG like it was with the LaRCSim Navion. At landing the proper pilot placement prevents poor position perception. Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] YASIM/Viewer mismatch
Curtis L. Olson writes: > >Jon S Berndt writes: >> On Wed, 3 Apr 2002 22:54:01 - >> "Jim Wilson" <[EMAIL PROTECTED]> wrote: >> >> >Ok, so are you saying that the lon/lat/alt values that >> >the fdm outputs are at the origin already adjusted for cg? >> >> JSBSim gives the lat/lon/alt of the CURRENT CG - NOT the >> origin of the structural frame. > >This means that currently as the CG moves (i.e. loading baggage, fuel, >people, etc.) the aircraft and the view point will move as well. >This is probably too small to normally notice and we typically aren't >changing the CG over time, but this does seem like something that >needs to be straightened out. Whatever the FDM's are returning for >position, it does need to be a fixed point relative to the airframe. FWIW I think the whole problem here stems from an old misunderstanding that although is a quite reasonable one is unfortunately mistaken ie CG has been considerd by some to be Center of Gravity and by others as Center of Geometry and its usage has gotten mixed up When we weren't changing the mass of the plane this made no difference but now that we are this needs to be cleared up I should have pointed this out at the time we started 'burning fuel' but I was well just 'burning' at the assumption that default behaviour could be changed ar will with out 'group' discussion. < which BTW would have led very quickly to exposing this CG confusion > FWIW My take on this is that all we need is a 'fixed' position ie 'Center of Geometry' returned by the FDM. This fixed position can be anywhere on the AirFrame and it needs to be described more exactly in the individual model's configuration file so as the Viewer part of the program can do it's thing Ciao Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jon S Berndt writes: > Oh, yeah, I meant to mention that. As I was writing that > statement the realization slowly came upon me that this > was likely the case. You are right that it won't be > noticed in most cases. But, when you do something like > drop a bomb your viewpoint will jump a small amount > discontinuously. It's annoying to do that. It could be > that the pilot viewpoint will need to change with the > opposite sense that the CG moves away from the original > CG. Maybe that's not optimal, either, though. Well as I understand from past discussion, there is already some reference point defined and all the other FDM 'stuff' is defined relative to that. Why not pass back that point, or some offset relative to that if you want to get fancy. We will definitely need coordination between the FDM location and the model location, but we have to do that anyway. And FlightGear already has support to do it's own view offset relative to the position the FDM is returning. I think this boils down to let's have the FDM worry about where the plane is, and let's have FlightGear worry about where the current view point is. 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
Re: [Flightgear-devel] YASIM/Viewer mismatch
Andy Ross <[EMAIL PROTECTED]> said: > Jim Wilson wrote: > > Andy Ross wrote: > > > The FDMs already take the c.g. into consideration. If a stopped > > > aircraft rotates (about the c.g, of couse), you will see the > > > coordinate origin moving. > > > > Well this might be useful to the 3D model. The effect probably isn't > > all that noticable compared to what we have now, but a real plane > > would pitch and roll about it's cg rather than the fixed "origin" as > > defined in a 3D model, wouldn't it? > > It would indeed. And it already does. Again, the rigid body magic > required to move the coordinate origin appropriately for a given > rotation about the center of gravity is the FDM's job. They already > do this; all the rest of the system has to do is draw the origin at > the right place. > > Once more: there's no error. Things are taken care of for you by the > physics code in the FDMs. > Ok, so are you saying that the lon/lat/alt values that the fdm outputs are at the origin already adjusted for cg? If so then how would that affect the axis of say pitch rotation on the c172 model? It's origin is at the firewall and the pitch rotation is always on the access that intersects there. Should we be doing something different? Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
On Wed, 3 Apr 2002 16:26:57 -0600 (CST) "Curtis L. Olson" <[EMAIL PROTECTED]> wrote: >The FDM defines some aribitrary reference point (i.e. on the firewall) >and provides the lon/lat/elev of that point. We provide the lat/lon/elev of the current _CG_. >The FDM really doesn't care about the actual FlightGear view point. True. >It won't know if the user is flying from the left seat, the right >seat, or seat 5A in the DC-3. True. >It seems like it would make much more sense for the flightgear side >(maybe the aircraft-set.xml file?) to provide the actual view offset >point relative to the FDM reference point. All true. I just want to make these points: 1) In JSBSim (and I am assuming in YASim, too) one can add a weight to where the pilot sits - or anybody for that matter, including someone seated in 5A or a piece of luggage, etc. This will typically be where the pilot sits. If you change the viewpoint you won't be changing where the "pilot ballast" is. You'll merely be changing the viewpoint. You won't be virtually walking around the aircraft. 2) The flight modeler will usually have an intimate knowledge of where the *pilot* sits from aircraft manufacturer 3-views or other means. In some cases this data is given directly as X, Y, Z coords in the structural frame. An aircraft 3D modeler might have this information, too, if working from the same diagrams, or [s]he can probably guess fairly well. 3) The turn coordinator instrument (to my knowledge) works in consideration of where it is located, typically right in front of the pilot. The accels sensed by this instrument include rotational effects at the pilots moment arm from the CG. 4) If FlightGear was ever to be hooked up to a motion base, the motion of the base might be linked to the second derivative of the body velocities _at_the_pilot_location_. Thus, again in this case and with point #3, above, the flight model still needs to know where the pilot is. I still recommend that the FDM be allowed to at least _recommend_ a pilot eyepoint, as some calculations inside the FDMs will use this value. It would be nice if this value could be useful to FlightGear. FlightGear could still be allowed to shift the viewpoint as it wished, but withe understanding of points 1 - 4, above. Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
I mildly disagree. I think the FGFS should require that the FDMs _and_ the aircraft models all have the reference point at the original manufacturer's defined reference point (so they all match nicely) even if this is done by a parametric offset that the FDM's configuration file has somewhere. The Aircraft's model file should contain an empty piece of movable airframe that is named "PILOT" and has the origin at the location of the obvious point of symmetry underneath a sitting person (grin) and has the up vector aligned with the slope of the seat back. This would allow the viewpoint stuff to specify pilot-centric viewpoints in terms of the PILOT location plus a specified distance that corresponds to the notional torso height of the simulated pilot to get the matrix. > Here's what make sense to me. > > The FDM defines some aribitrary reference point (i.e. on the firewall) > and provides the lon/lat/elev of that point. > > The FDM really doesn't care about the actual FlightGear view point. > It won't know if the user is flying from the left seat, the right > seat, or seat 5A in the DC-3. > > It seems like it would make much more sense for the flightgear side > (maybe the aircraft-set.xml file?) to provide the actual view offset > point relative to the FDM reference point. > > Curt. > > > David Megginson writes: > > Andy Ross writes: > > > > > We're evidently talking past each other. What you say is true. It is > > > *also* true that, under YASim, you have non-zero pilot offset numbers. > > > These are (1) defined by the FDM, in conflict with similar definitions > > > in the model, and (2) in an apparently different coordinate space from > > > the one the viewer is expecting. > > > > > > The viewer must be using those properties > > > (/sim/view/pilot/x-offset-m), no? How else would the settings by > > > YASim be affecting the view location? > > > > OK, here's how I had understood things: > > > > 1. The FDM sets the plane's lat/lon/alt to the ideal pilot viewpoint. > > > > 2. /sim/view/pilot/*-offset-m are properties controlled by the user > >and/or the view manager, and are added to the lat/lon/alt supplied > >by the FDM. > > > > Here's how Andy understands things: > > > > 1. The FDM sets the plane's lat/lon/alt to the origin, which is any > >arbitrary point on the plane's body. > > > > 2. /sim/view/pilot/*-offset-m are properties controlled by the FDM to > >give the offsets from the origin to the ideal pilot viewpoint. > > > > I'd like to reserve the /sim/view properties literally for allowing > > the user to move around inside (or outside) the plane. If my #1 is > > not correct, perhaps we should all the FDMs to put offsets somewhere > > under the FDM hierarchy. > > > > > > All the best, > > > > > > David > > > > -- > > David Megginson > > [EMAIL PROTECTED] > > > > > > ___ > > Flightgear-devel mailing list > > [EMAIL PROTECTED] > > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > > -- > 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 > > ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jon S Berndt writes: > I'm not sure I understand what you are saying, here. I will say, > however, that if there is a viewpoint given for pilot eyepoint in a > JSBSim config file it would be good to reference it somehow (even > if you copy it into an aircraft 3d model file) because it will be > accurate information for the *pilot* eyepoint, if nothing else. At least it would be close. I'm sure that the eyepoints are different for a 5'2" pilot and a 6'4" pilot, and we also want to be able to model leaning forward, etc. All the best, David -- David Megginson [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Andy Ross writes: > We're evidently talking past each other. What you say is true. It is > *also* true that, under YASim, you have non-zero pilot offset numbers. > These are (1) defined by the FDM, in conflict with similar definitions > in the model, and (2) in an apparently different coordinate space from > the one the viewer is expecting. > > The viewer must be using those properties > (/sim/view/pilot/x-offset-m), no? How else would the settings by > YASim be affecting the view location? OK, here's how I had understood things: 1. The FDM sets the plane's lat/lon/alt to the ideal pilot viewpoint. 2. /sim/view/pilot/*-offset-m are properties controlled by the user and/or the view manager, and are added to the lat/lon/alt supplied by the FDM. Here's how Andy understands things: 1. The FDM sets the plane's lat/lon/alt to the origin, which is any arbitrary point on the plane's body. 2. /sim/view/pilot/*-offset-m are properties controlled by the FDM to give the offsets from the origin to the ideal pilot viewpoint. I'd like to reserve the /sim/view properties literally for allowing the user to move around inside (or outside) the plane. If my #1 is not correct, perhaps we should all the FDMs to put offsets somewhere under the FDM hierarchy. All the best, David -- David Megginson [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson wrote: > Andy Ross wrote: > > The FDMs already take the c.g. into consideration. If a stopped > > aircraft rotates (about the c.g, of couse), you will see the > > coordinate origin moving. > > Well this might be useful to the 3D model. The effect probably isn't > all that noticable compared to what we have now, but a real plane > would pitch and roll about it's cg rather than the fixed "origin" as > defined in a 3D model, wouldn't it? It would indeed. And it already does. Again, the rigid body magic required to move the coordinate origin appropriately for a given rotation about the center of gravity is the FDM's job. They already do this; all the rest of the system has to do is draw the origin at the right place. Once more: there's no error. Things are taken care of for you by the physics code in the FDMs. Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com "Men go crazy in conflagrations. They only get better one by one." - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
On Wed, 3 Apr 2002 20:47:57 - "Jim Wilson" <[EMAIL PROTECTED]> wrote: > If there is something that I need to use that comes >from the FDM let me know what it is and how to use it. > But I'm not going to be setting the eyepoint with FDM data (other than >offseting it from the available origin value). Because, as I said > before, the eyepoint is not necessarily the pilot's eye. I'm not sure I understand what you are saying, here. I will say, however, that if there is a viewpoint given for pilot eyepoint in a JSBSim config file it would be good to reference it somehow (even if you copy it into an aircraft 3d model file) because it will be accurate information for the *pilot* eyepoint, if nothing else. >It looks like most of the 3D models have the "origin" on >the firewall. I think that is what JSBsim is using too. Actually, that is not necessarily the case. Tony created the coordinate frame there and its just as good as anything else. For us FDM guys, for the most part, it is the relative locations of various items that is most important. However, the X-15 and Space Shuttle, etc. models use various other conventions for structural frame origin. >Well this might be useful to the 3D model. The effect probably isn't all >that noticable compared to what we have now, but a real plane >would pitch and roll about it's cg rather than the fixed "origin" as > defined in a 3D model, wouldn't it? FWIW, the CG location can/will change as fuel is burned off and external stores (if present) are dropped. Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Andy Ross <[EMAIL PROTECTED]> said: > Jim Wilson wrote: > > That's ok, but as I said earlier, the offsets that the viewer will > > use will be defined elsewhere because they are not necessarily the > > true actual pilot's eye point. > > We're evidently talking past each other. What you say is true. It is > *also* true that, under YASim, you have non-zero pilot offset numbers. > These are (1) defined by the FDM, in conflict with similar definitions > in the model, and (2) in an apparently different coordinate space from > the one the viewer is expecting. > > The viewer must be using those properties > (/sim/view/pilot/x-offset-m), no? How else would the settings by > YASim be affecting the view location? > Ah ok. After I get done with the configurable viewer, those values won't be used by the viewer. You are correct we have been using them if they are set by Yasim. Under other flight models (eg JSBsim) the values defined in the xml are being used. When I get done those offsets will be in each view with xml and not in that path. If there is something that I need to use that comes from the FDM let me know what it is and how to use it. But I'm not going to be setting the eyepoint with FDM data (other than offseting it from the available origin value). Because, as I said before, the eyepoint is not necessarily the pilot's eye. > > Right now I believe the model's origin is being placed at the > > lon/lat/alt that is set by the FDM, converted to fg coordinates. > > This is correct, and exactly as it should be (so long as the FDM and > model agree on where the origin is, at the nose, for example). > It looks like most of the 3D models have the "origin" on the firewall. I think that is what JSBsim is using too. > > Note that this isn't taking center of gravity into consideration, so > > at some point we should be adding in an offset to cg too (or is > > lon/lat/alt at cg)? > > Eep, no. The FDMs already take the c.g. into consideration. If a > stopped aircraft rotates (about the c.g, of couse), you will see the > coordinate origin moving. We certainly don't want code outside the > FDMs to have to worry about this. The c.g. is an internal parameter > of the FDM. Other code might want to inspect it out of curiosity, but > we *certainly* don't want the view code worrying about rigid body > dynamics. :) > Well this might be useful to the 3D model. The effect probably isn't all that noticable compared to what we have now, but a real plane would pitch and roll about it's cg rather than the fixed "origin" as defined in a 3D model, wouldn't it? Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Andy Ross <[EMAIL PROTECTED]> said: > Jim Wilson wrote: > > Ultimate, the pilot position comes from the tag in the YASim > .xml file. The rationale here was that this was the best place to put > the information about the cockpit position was in the aircraft > definition. But that was before the 3D model work got done. Now, > there are *two* aircraft definitions: one to decide on physical > performance and one to control visual display. Basically, we need to > pick one mechanism. I think the simplest thing to do would be to yank > the YASim mechanism (and whatever JSB and UIUC do) and use > the model stuff only. Then, at least, we're guaranteed to be > consistent across FDMs so long as we get the origin correct. > That's ok, but as I said earlier, the offsets that the viewer will use will be defined elsewhere because they are not necessarily the true actual pilot's eye point. The only thing I can think of that the FDM should be concerned about reporting (for viewer/model use) other than orientation is the aircraft model position...ie where the origin should be. Right now I believe the model's origin is being placed at the lon/lat/alt that is set by the FDM, converted to fg coordinates. Note that this isn't taking center of gravity into consideration, so at some point we should be adding in an offset to cg too (or is lon/lat/alt at cg)? Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson wrote:
> Andy Ross wrote:
> > David Megginson wrote:
> > > Something is overwriting the xyz offsets in the c172-3d-set.xml or
> > > maybe it isn't reading that file? Those are defaults from
> > > somewhere...probably from c172-set.xml.
> >
> > YASim _sets_ those offsets based on its own configuration. I think
> > this is a problem of data ownership -- who "owns" the location of
> > the cockpit? I argue that it's the FDM, since it's the code
> > responsible
>
> That isn't the issue here though. Those are just the offsets from the
> lon+lat+alt to the eyepoint and it was those that were off. Where
> that origin is FDMwise is another issue and not related to what David
> was observing.
No, I meant the airframe offsets, not the global ones. The following
code appears in YASim.cxx (the negations are due to the difference in
coordinate sense):
// The pilot's eyepoint
float pilot[3];
a->getPilotPos(pilot);
fgSetFloat("/sim/view/pilot/x-offset-m", -pilot[0]);
fgSetFloat("/sim/view/pilot/y-offset-m", -pilot[1]);
fgSetFloat("/sim/view/pilot/z-offset-m", pilot[2]);
Ultimate, the pilot position comes from the tag in the YASim
.xml file. The rationale here was that this was the best place to put
the information about the cockpit position was in the aircraft
definition. But that was before the 3D model work got done. Now,
there are *two* aircraft definitions: one to decide on physical
performance and one to control visual display. Basically, we need to
pick one mechanism. I think the simplest thing to do would be to yank
the YASim mechanism (and whatever JSB and UIUC do) and use
the model stuff only. Then, at least, we're guaranteed to be
consistent across FDMs so long as we get the origin correct.
The axis mixup, though, still requires a solution. My guess is that
the new viewer draws the new models correctly in their (new)
coordinate system, but misinterprets the offset information generated
by the FDMs.
Andy
--
Andrew J. RossNextBus Information Systems
Senior Software Engineer Emeryville, CA
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- Sting (misquoted)
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Re: [Flightgear-devel] YASIM/Viewer mismatch
Jon S Berndt <[EMAIL PROTECTED]> said: > On Wed, 03 Apr 2002 09:32:12 -0800 > > >> Something is overwriting the xyz offsets in the c172-3d-set.xml or > >> maybe it isn't reading that file? Those are defaults from > >> somewhere...probably from c172-set.xml. > > Andy Ross <[EMAIL PROTECTED]> replied: > > >YASim _sets_ those offsets based on its own configuration. I think > >this is a problem of data ownership -- who "owns" the location of the > >cockpit? I argue that it's the FDM, since it's the code responsible > >for other issues of aircraft geometry. But then the model wants it > >too. > > I agree. The published geometric and physical properties > of the aircraft - necessary for the creation of an > aircraft flight model - often includes if not the exact > eyepoint of the pilot at least a diagram that allows the > flight modeler to deduce it. That's fine, but this is really anybody's eye (as far as the viewer is concerned). It could for example be a passenger in 5A on a dc3. It doesn't need to be tied to the FDM. Now the origin location for the 3d model itself is a different story and that probably should be addressed. Right now it is set to whatever the fdm is reporting for lon/lat/alt (plus model offsets that I think aren't being used any more?). Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
David Megginson <[EMAIL PROTECTED]> said: > > If I was the only one to have say in this I'd make the xyz in the > > model files conform to the expected by the user axes (x across, y > > up/down, z depth). It is also what would be expected by anyone who > > is unfamiliar with plib but has done other 3d programming or > > modeling. The FDM and other stuff I'd leave alone, but the panel, > > model, and viewer that end users are most likely to mess around > > with, I'd make consistent. > > Fair enough, but it would drive the aero people crazy. > Should I just sit on this until we hear from some model people? Or should I change something? Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
On Wed, 03 Apr 2002 09:32:12 -0800 >> Something is overwriting the xyz offsets in the c172-3d-set.xml or >> maybe it isn't reading that file? Those are defaults from >> somewhere...probably from c172-set.xml. Andy Ross <[EMAIL PROTECTED]> replied: >YASim _sets_ those offsets based on its own configuration. I think >this is a problem of data ownership -- who "owns" the location of the >cockpit? I argue that it's the FDM, since it's the code responsible >for other issues of aircraft geometry. But then the model wants it >too. I agree. The published geometric and physical properties of the aircraft - necessary for the creation of an aircraft flight model - often includes if not the exact eyepoint of the pilot at least a diagram that allows the flight modeler to deduce it. The flight modeler may also want to place a point mass weight where the pilot "sits", too, so the information is very much critical to the aircraft flight modeler. JSBSim will include the eyepoint of the pilot - as well as ballast to represent the pilot - regardless of whether or not the modeler uses it. I suggest that the FDM be looked to for supplying such a value - at least as a recommendation. Also, be it known that the day is coming when a standard method of describing aircraft via some form of XML specification file is present. It is likely that the coordinate system used for such a standard specification will be one that is already a standard. That is, the aircraft structural frame: X axis increasing out the tail, Y axis increasing out the right side of the aircraft (when looking forward), and the Z axis of course positive upwards to complete the right-handed coordinate frame. The origin would typically be somewhere at the nose or just ahead of the nose of the aircraft, with the X axis either coincident with the centerline or parallel to it but below it (in order that all the Z coordinates would be positive numbers). It would be nice if there was some coherent and stable method of describing aircraft models and how they relate to the aircraft structural frame, if not coincident. Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Andy Ross <[EMAIL PROTECTED]> said: > Jim Wilson wrote: > > David Megginson wrote: > > > I tried this > > > > > > fgfs --aircraft=c172-3d --fdm=yasim > > > > > > and had an interesting experience -- I ended up sitting on the runway > > > a meter or two to the right of the plane, rather than inside it. > > > > Something is overwriting the xyz offsets in the c172-3d-set.xml or maybe it > > isn't reading that file? Those are defaults from somewhere...probably from > > c172-set.xml. > > YASim _sets_ those offsets based on its own configuration. I think > this is a problem of data ownership -- who "owns" the location of the > cockpit? I argue that it's the FDM, since it's the code responsible That isn't the issue here though. Those are just the offsets from the lon+lat+alt to the eyepoint and it was those that were off. Where that origin is FDMwise is another issue and not related to what David was observing. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson wrote:
> It's already inconsistent. The model is one way (as you expected)
> and the panel xml is x across and y up/down.
But this is OK -- these are different coordinate systems with
different usages. You'll never put airframe coordinates into the
panel XML, nor use panel coordinates in a model file.
The problem with inconsistencies is when multiple conventions get used
for the *same* coordinates. To take airframe coordinates as an
example (I'm not 100% certain on some of these):
JSBSim uses X-forward, Y-right, Z-down
YASim uses X-forward, Y-left, Z-up
The model ac3d file appears to use X-right, Y-forward, Z-up
All of these are right handed coordinates, and any of them could work.
Internally, it really doesn't matter what convention the subsystem
uses (YASim converts its coordinates to JSBSim conventions before
exporting them, for example). But externally ("on the bus", as it
were), we really need to pick one and only one canonical way to
represent a unique point on the airframe.
Andy
--
Andrew J. RossNextBus Information Systems
Senior Software Engineer Emeryville, CA
[EMAIL PROTECTED] http://www.nextbus.com
"Men go crazy in conflagrations. They only get better one by one."
- Sting (misquoted)
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Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson wrote: > David Megginson wrote: > > I tried this > > > > fgfs --aircraft=c172-3d --fdm=yasim > > > > and had an interesting experience -- I ended up sitting on the runway > > a meter or two to the right of the plane, rather than inside it. > > Something is overwriting the xyz offsets in the c172-3d-set.xml or maybe it > isn't reading that file? Those are defaults from somewhere...probably from > c172-set.xml. YASim _sets_ those offsets based on its own configuration. I think this is a problem of data ownership -- who "owns" the location of the cockpit? I argue that it's the FDM, since it's the code responsible for other issues of aircraft geometry. But then the model wants it too. I dunno. Maybe the sane thing to do would be to put the cockpit location into the model file, and work really hard to insure that the coordinate origin is identical between the representations? Yanking this out of YASim is easy. Beyond that, there appears to be an axis mismatch somewhere. I verified that the code worked with the old viewer (the 747 cockpit was high, the 172 slightly to the left, etc...), but things might have changed since. We really need to write up a "coordinates bible" that defines, once and for all, the conventions we're using. :) Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com "Men go crazy in conflagrations. They only get better one by one." - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson writes: > It's already inconsistent. The model is one way (as you expected) and the > panel xml is x across and y up/down. Yes, I know. One consideration, though, is that each panel is (soon) going to be projected to any arbirtary location and orientation in the aircraft, so you can think of it as being drawn from overhead and then rotated around. > If I was the only one to have say in this I'd make the xyz in the > model files conform to the expected by the user axes (x across, y > up/down, z depth). It is also what would be expected by anyone who > is unfamiliar with plib but has done other 3d programming or > modeling. The FDM and other stuff I'd leave alone, but the panel, > model, and viewer that end users are most likely to mess around > with, I'd make consistent. Fair enough, but it would drive the aero people crazy. All the best, David -- David Megginson [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
David Megginson <[EMAIL PROTECTED]> said: > > Sorry for the confusion there. I think that it's probably not a good > idea to do things that way -- we should stick with normal aircraft > axes for consistency with the rest of FlightGear, at least at the > property level (a GUI can present things differently, of course). > It's already inconsistent. The model is one way (as you expected) and the panel xml is x across and y up/down. If I was the only one to have say in this I'd make the xyz in the model files conform to the expected by the user axes (x across, y up/down, z depth). It is also what would be expected by anyone who is unfamiliar with plib but has done other 3d programming or modeling. The FDM and other stuff I'd leave alone, but the panel, model, and viewer that end users are most likely to mess around with, I'd make consistent. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
Jim Wilson writes: > That is intentional. Before the pilot and chase were different > than each other (or seemed that way). Prior to knowing anything > about using plib or Opengl, I always assumed as a user that x was > across the screen, y was up and down and z was depth. That is I > think most intuitive to the xml user, and the fact that it doesn't > coincide what's going on in the viewer black box is not important. > Anyway, it is in my change log entry, documented in the source, and > all my proposal stuff ;-) Sorry for the confusion there. I think that it's probably not a good idea to do things that way -- we should stick with normal aircraft axes for consistency with the rest of FlightGear, at least at the property level (a GUI can present things differently, of course). All the best, David -- David Megginson [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASIM/Viewer mismatch
David Megginson <[EMAIL PROTECTED]> said: > I tried this > > fgfs --aircraft=c172-3d --fdm=yasim > > and had an interesting experience -- I ended up sitting on the runway > a meter or two to the right of the plane, rather than inside it. > Something is overwriting the xyz offsets in the c172-3d-set.xml or maybe it isn't reading that file? Those are defaults from somewhere...probably from c172-set.xml. > Things got even more interesting when I started playing with the view > position offsets, because everything was wrong: the x offset moved the > viewpoint sideways (y-axis), the y offset moved the viewpoint up and > down (z-axis), and the z offset moved the viewpoint backwards and > forwards (x-axis). > That is intentional. Before the pilot and chase were different than each other (or seemed that way). Prior to knowing anything about using plib or Opengl, I always assumed as a user that x was across the screen, y was up and down and z was depth. That is I think most intuitive to the xml user, and the fact that it doesn't coincide what's going on in the viewer black box is not important. Anyway, it is in my change log entry, documented in the source, and all my proposal stuff ;-) > I cannot figure out why this is happening. YASIM uses a different > coordinate system internally, but there should be no direct dependency > between the view offsets and the FDM -- YASIM simply reports the > geodetic position (lon/lat/alt) and orientation (roll/pitch/heading) > for the model itself, and the viewer positions the model > appropriately. > There's no interface problem, only a settings file issue. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
