Determining writable offsets

[GregG]

Hello Pete,

The new flight start determination offset you added to 3.12 is working marvelously, I'm pleased to say. Thanks, again. My sim run-up feature works just as planned.

I have a new question. I've been using FSInterrogate to try and find an offset to allow me to adjust the view direction. I located 05D2 which seems to be a word value with 0 = North and originally appeared to be just what I was looking for. However, it seems to only work as read only, as values written to this offset are just written over again by FS9. (At least with writting using FSInterrogate, I have not tried to write with FSUIPC but I assume the results will be the same.)

Is it possible there is a variable that I need to flag to force the change or have I just stumbled on a read-only offset that is useless for my purposes?

The feature that would use this is extremely low priority, so I'm not going to dwell on it too much, but I wanted to make sure I wasn't missing anything obvious. That FSInterrogate is really handy now that I figured out how to make use of it. :)

Thanks,

Greg

[Pete Dowson]

I have a new question. I've been using FSInterrogate to try and find an offset to allow me to adjust the view direction. I located 05D2 which seems to be a word value with 0 = North and originally appeared to be just what I was looking for. However, it seems to only work as read only, as values written to this offset are just written over again by FS9. (At least with writting using FSInterrogate, I have not tried to write with FSUIPC but I assume the results will be the same.)

FSInterrogate is using FSUIPC, so it is identical.

I've no idea what is in 05D2. What values apart from 0=North do you see? What view direction are you trying to adjust?

I provided an easy to use selection for the main view directions at 3126, but I never found a way to tell which the current view direction was.

Is it possible there is a variable that I need to flag to force the change or have I just stumbled on a read-only offset that is useless for my purposes?

I don't know what 05D2 is, so, sorry, I've no idea.

Regards,

Pete

[GregG]

Indeed, I wasn't very specific. Let me remedy that. :) It is 0 at north and continues around to 65535. 16384 would be east, etc. More testing needs to be done but it seems that when on the ground (just after loading a flight, at least) this value orients on the aircraft. However, once up in the air it orients on north. It's definately not indicated north though. I assume there's an FS9 internal north and it uses that, but I'm not too knowledgeable about that. It seems to be, in Seattle, about 20 degrees off of indicated north. (0=340deg/32768=160deg)

So ~0 = straight ahead/north, 16384 is right/east, 49152 is left/west, etc. Or you can read it as a smallint and it is 0 = straight ahead/north 16384 is right/east and -16384 is left/west.

As for which view it pertains to, it seems to be valid for cockpit, VC and spot views. Of course, in true cockpit view, the value stays near 0 (56 on my test). I did not yet test tower view as I never use it. I haven't determined if there is another value for the vertical plane, but it should be easy for me to find if you'd like. Just during those tests I noticed that 030A and 05D0 are related.

Writing to offset 3126 doesn't work for me, unfortunately, as I need minute control (< 1 degree). For my needs I'm looking to control this in VC and spot views.

Thanks again,

Greg

[Pete Dowson]

It seems to be, in Seattle, about 20 degrees off of indicated north. (0=340deg/32768=160deg)

That's the magnetic variation at Seattle. True north is 20 degrees different from Magnetic North. to find true North in FS, put your aircraft into Slew mode (press 'Y') then press the Space bar. The aircraft will face true North and you can read the variation off the compass/heading indicator.

So ~0 = straight ahead/north, 16384 is right/east, 49152 is left/west, etc. Or you can read it as a smallint and it is 0 = straight ahead/north 16384 is right/east and -16384 is left/west.

This is standard FS representation of headings -- as used and explained for offsets 0582 (the high part of 0580) and the wind direction indicators, and so on. It is also used for the Mag Var at 02A0.

As for which view it pertains to

But is it the view direction of the nose direction? Does it change smoothly as you pan, or if you use view selectors? I'll look at it tomorrow if I get time, but it doesn't sound very useful if it only works on the ground ...?

Writing to offset 3126 doesn't work for me, unfortunately, as I need minute control (< 1 degree). For my needs I'm looking to control this in VC and spot views.

Active Camera does it very well, but I don't know how, and I don't suppose the author will give away any of his secrets. But you could ask him. You never know.

Regards,

Pete

[GregG]

It's definately the view direction and not the nose direction. And it seems to work just fine from both the ground and the air, it just uses two different orientations. Under certain circumstances 0 is direction the aircraft nose is pointing. At other times 0 is north. As long as one can detect which mode is in use, the value can be understood. Further testing will need to be done to figure that part out. I thought it was air vs. ground but that does not appear to be the case although it might be related.

If you are in gradual transition mode, the value moves exactly with the view rotation. So it will move quickly and then slow down until it's unchanging and then start moving back, just like gradual transition. If gradual transition is off then it moves in chunks, just like the view. If you use view selectors it changes in large chunks. Again, just like the view. Essentially, the value appears to be exactly the view direction regardless of other settings.

Of course, even if this value is useful for reading, which its seems to me that it is, that doesn't help with my wish to write to it. I agree that the Active Camera folks have solved this and I was just hoping to solve it independantly. I feel that simple mouse panning is something that should have been in MSFS to begin with, as it is with most flight sims, and just wanted to produce a freeware option for this minuscule subset of Active Camera's impressive functionality. I have no interest in producing a similar product, but I doubt I can convince them of that.

Thanks,

Greg

Edit: On further testing it appears there is only one "mode". I was just misinterpreting some results. 0 is north and is not related to the nose direction. I was confused due to the fact that I was getting 0 at 340 (as the Seattle Tacoma starting runway is on that bearing). Then, once I realized that this was due to indicated north not being the same as the internal (true) north, I didn't "rethink" the situation.

Edit2: To test this I did as you suggested, I put it into slew and pressed the space bar. The offset in question went to 0 in cockpit mode. 0 in VC mode if I press space again (to reset the head position), and 0 in spot mode if I press Shift+Num2 (to reset the view to looking in line with the nose).

Then, in spot mode, I used my hat to rotate (the view not the airplane) one notch to the right. The offset changed to 2700. A second notch goes to 5400 and so on. This works in VC mode as well. From looking straight ahead with the aircraft pointing due north, moving one notch to the right brings the value to 1350, two notches to 2700, etc.

Apparently with my settings one hat notch in VC mode turns the view one half as much as one hat notch in Spot mode.So this does indeed seem to be a perfect representation of the view direction on the horizontal plane.

[Pete Dowson]

So this does indeed seem to be a perfect representation of the view direction on the horizontal plane.

Okay, thanks. I've now checked it here. I'll check in FS2002 and maybe FS2000 too, see if they have the same thing. I'll add it to the SDK documentation.

Regards,

Pete

[Pete Dowson]

(LATER):

I've just checked it in FS2002 and it's the same there. I can't get my FS2000 installation running and haven't time to re-install it, so I tried my old bare-bones FS98. Guess what? It's the same there too -- well, almost. There seems to be a permanent deviation from 0 = true North in FS98. But it's only a degree or so. Odd. It isn't related to MagVar, it's the same all over the world. It was probably down to the longitudinal axis of the aircraft I used being off-centre or something.

Anyway, I'm going to be bold and assume that, since it is there in FS2004, FS2002 and FS98, it'll be the same in FS2000!

Odd that it's not been 'discovered' before. Evidently it isn't of interest to many!

Regards,

Pete

[GregG]

Thanks for the update, Pete. Hopefully, someone will find it useful. :) I don't think I'm going to find a writable solution with a reasonable amount of effort, and my project is still in its infancy, so I'll probably leave it alone with the huge amount of work I have left to do. It just seemed that it would be a nice little draw, but it really was outside the purview of the project to begin with. I suspect that if there were an easy solution, there'd already be less feature-rich freeware alternatives to Active Camera.

On the good side I gained some experience with FSInterrogate, which is good, as there are already several MSFS variables that I'm going to need that are not yet documented for FSUIPC. You'll be hearing from me again, I'm sure, hopefully bearing new discoveries and not just asking questions. ;)

Thanks again,

Greg