> I mean no disrespect, nor do I question your ability. But, you don't > seem to entirely understand the power of the offsets property. If the > FDM reports a position, say the nose, as you intend to do. Now say that > the 3D model has the origin at the tail. All is not lost. As long as > someone can determine the deltas x,y,z between these two fixed points, > these deltas become the /offsets/ properties in the XML wrapper file that > tell the IG software how to shift the 3D model to the FDM's reported > position.
Yes. I agree with this. This is obvious -- sometimes we import 3D models made by others. I am not implying at all that the origin (0,0,0) must be the nose for 3D models (although it could be). > That JSBSim reported the nose is not significant. Yes is it. Because it must be understood what JSBSim is reporting: does the lat/lon/alt reported by JSBSim to FlightGear represent the location of the tail, the nose, the dynamic or empty-weight CG, or ... ? If this is standardized to a commonly understood point, it makes it easier for newbies to relate 3D models to the flight model. Otherwise, it will lead to confusion: how does a newer or less capable user know what these offsets should be. They would have to dig into FlightGear / JSBSim documentation (with the associated various degrees of completeness). If referencing the empty weight CG, they will have to research, or do trial and error, or do some math based on what is in the config file. It's easier to state that a physical and observable point is the reference point. > It's fixed point to fixed point but they don't need to be the same fixed > point. I've never said that the 3D model origin has to be the tip of the nose - in fact I expect it NOT to be. This is where the offset file/properties comes in. But one must know what the "registration marks" are. I argue that for 3D model designers it is easier to identify the tip of the nose more accurately than where the empty weight CG is. And, it must be publicly announced just what the FDM is reporting for lat/lon/alt. This is what I mean by agreed-upon convention. > >I am trying to preclude confusion amongst the audience of 3D modelers and > >flight model creators. > > This is a false sense of security. Not all FDMs will use the nose, nor > will all 3D models. If all FDMs report the lat/lon/alt location of the same point, that will make things more "plug and play". Otherwise, the offset properties will need to be changed per FDM, per aircraft. A common VRP ought to make the aircraft models more interchangeable, without changing offset properties. But, again, the 3D model does not need (and I don't expect it) to use the nose as the *origin*, it just has to HAVE a nose. Jon _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
