On Friday 02 May 2008 18:36, Melchior FRANZ wrote: > * LeeE -- Friday 02 May 2008: > > I am curious about why using the tail location as the visual > > reference point is abusing the FDM's internal reference > > system but using the nose is not. > > That's a misunderstanding. I didn't mean that one place is OK, > and another is an abuse. What I meant to say is that fgfs > mandating *any* particular internal(!) FDM reference point only > for easier positioning is an abuse. The nose isn't used because > of that, but rewriting the FDM config files to use the tail > would be. (Not all aircraft use the nose, anyway. The bo105 > uses the main rotor axis. :-)
The rotor axis really makes sense for helis but yeah, some of my old aircraft haven't been adjusted to use the nose and still use an arbitrary reference point, but as long as the model and FDM line up no one's going to notice. > > So, if positioning should be made easier, then not the internal > FDM reference point should be changed, but there should simply > be an offset from the reference point. That's AFAIK what JSBSim > does already, and what YASim could easily do. > > > Isn't the chase distance, along with the view angle, a user > > preference setting? If so, how can we justify saying that a > > user preference is set badly? > > Chase distance isn't (usually) a user preference. It's something > that the aircraft developer defines. And I did intentionally say > "badly", and not "wrongly". Look at the 737-300, for example. The > chase view doesn't exactly "chase" the 737. It almost sits on the > tail! You don't even see the whole aircraft at once, can't really > follow its movements nicely. The 777-200ER is much better, though > still a tad to close IMHO. (AN-225 -> too close :-) Hmm... I've always regarded both chase distance and view angle as user settings, not only because they're just a visual setting but because FG offers a user dialogue - the one with the little dials - to set them. If they were only changeable via the property tree browser then I'd agree with you but providing a user interface to change them makes them a user setting, whether that's a good idea or not:) Actually, when I'm setting the chase distance, the most important factor is the field of view. On my system, which isn't very powerful these days, increasing the field of view naturally increases the render load too, so I stick to the default 55 deg FoV, and try set the chase distance so that the entire aircraft is a reasonable size in the screen. I seem to remember having problems setting a great enough chase distance with the AN-225 though, because it seemed to be clamped at 90m, iirc. With the default FoV the wing-tips are clipped and it occupies too much of the screen. I don't know if there's still a limit on the chase distance. > > Normally it would only be a matter of taste. The aircraft > developer defines it how s/he likes it best. But because this is > the main indicator for the aircraft size and useful for other > view related things, it would be better if used consistently. > (Sure, I could also count the number of tanks/wheels/engines/... > :-) > > (Fly-by needs the size for calculating the sideways distance from > the "predicted" target point, but also for determining the > distance threshold under which the view point shouldn't be > changed at all, because the aircraft is hovering, taxiing very > slowly, etc.) > > m. Sounds reasonable, although if I'd done it I would have probably just used the chase distance for the lateral/vertical offsets and a time period for the viewpoint update - heh - and make the update time period a user setting too:) LeeE ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
