[Flightgear-devel] Not really a bug, sort of, I think?

[Rob S. Jr. <rm...@ya...>]

Hi, developers...

In attempting to design some more "animated scenery" in the vein of my rocking boats at KMTN, I attempted to make some moving Metrorail trains at the approach end of runway 15 at KCGS, and in doing so, exposed what I shall call a "limitation" rather than a "bug", since I suppose the code is just not meant to do what I am attempting to do with it.  And while I understand that a new AI ground vehicle system will be able to do what I want, I figure I will mention this anyway, in case it becomes relevant later for some currently unseen reason.

Anyway, what I was attempting to do was to create a Metro train in a given position, which I shall refer to as "its origin", on a model of a raised track just off of the approach to KCGS 15.  I then used a time-based formula with a sine wave to calculate an "offset", which ranged from + to - something like three thousand meters, to have the train essentially oscillate back and forth over a 3-mile section.  Doing so in realistic time intervals (five minutes or so) would create a reasonable illusion of multiple trains passing back and forth past the airport on a more-or-less normal schedule.

The limitation I discovered was this: if the user's view is not pointed at the train's "origin" point, the trains disappear from view, regardless of their "current" (i.e. offset) position.

While I understand that I was bending the code to attempt to do something it wasn't originally intended for, my question is this:  does it make sense to suggest that the code be patched (and, mind you, I do not know how to do this) so that the model's OFFSET position is taken into account, instead of its "listed" ("origin") position?  I understand that the AI vehicle system will soon (or even now?) do what I wanted this hack to do, but perhaps there are some other (more legitimate) reasons that this issue should be examined and corrected -- or perhaps it should be fixed in case of future, unforeseen applications of large offset values.

Thoughts?

Cheers,
-R. (MD-Terp)

 Robert M. Shearman, Jr.
Transit Operations Supervisor,
University of Maryland Department of Transportation
also known as rm...@um...