> I don't see that.  What is the benefit of a configurable VRP at
> all, if the 3D modeller cannot set it in the XML config file for
> the model?

Aaaaaaargh!

It's the FDM's item to configure. See below.

> In that case, you might as well just report the 0,0,0
> point, as Jim suggests.

This would require that the visual modeler have access to the flight
dynamics model (in our case, for instance, c172.xml). What if the flight
model does not exist yet (someone's got to be first). The VRP is an
agreed-upon point - a convention - that the flight modeler and the 3D
modeler can be assured will give correct placement. The flight modeler and
the 3D modeler don't even need to _know_ each other in this case. They can
exist in different worlds. There's _got_ to be some kind of convention here,
because the flight modeler (for us) defines things in structural coordinates
of which the 3D modeler will likely have NO knowledge of before building a
3D model. It boils down to this:

The flight modeler and the 3D modeler will have different base coordinate
frames of importance. The obvious choice of common origin - the CG - floats,
so that's out. There then must be a "registration mark" that the two worlds
can agree on that will allow seamless overlay. IIRC, YASim provides for the
origin at the nose tip too (or something close to that). JSBSim can provide
that, and I (and others) have proposed that the tip of the nose is as good a
convention as any. As far as a problem with the spinner missing: gimme a
break. There are always going to be special cases. The 3D modeler can remove
the spinner if they want to to provide a realistic model leave the origin
where it was or would be _with_ a spinner.

We've got a chance to make progress, the code is there, I want to move this
forward and move onto something else. If it ends up being a loser approach,
we can change it then, with some experience to back us up. I'm sick to death
of rehashing this.

Jon


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