David Megginson <[EMAIL PROTECTED]> said: > Jon S Berndt wrote: > > > JSBSim made a change recently that is likely not yet in FlightGear CVS. > > The lat/lon/alt position now reported by JSBSim (CVS) is the position of > > the VRP (Visual Reference Point) - i.e. the tip of the prop hub (or > > similar nose tip location on non-prop aircraft). As long as the > > aircraft is placed in the scene so that the nose of the 3D model falls > > at the location reported by JSBSim - everything works out. > > I'm not sure I see how this helps -- the model code still doesn't know where > the CG is, so it still doesn't know where the centre of rotation for the > model should be.
The distance between any two vertices of a 3D model stays the same when you pitch the aircraft. For example: if you subtract the forward most vertext at the root of the left wing, from the vertext at the tip of the nose cone, you will always get the same X,Y,Z dimmension. No matter what the attitude of the aircraft is. That is why the model code does not need to know where the CG is. The 3D model designer does need to know the FDM "origin" or "reference point" or whatever you want to call the vertex in space at which the FDM reports the lon/lat/alt of the aircraft. So if she puts the origin of the model (0,0,0) in that place, the 3D model will rotate correctly. Best, Jim _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
