FSUIPC for "Visual Only" app (revisited)

[noodnik2]

You can make FS respond to external positioning in one of two ways -- either as an observer in a multiplayer connection (where it thinks it is connected to another FS doing the flying and is participating only as an observing passenger), or through an interface like FSUIPC manipulating the six degrees of freedom (LLAPBH -- latitude, longitude, altitude, pitvh, bank and roll).

Pete,

I'm working on a program attempting to re-create an actual flight (recorded in a GPS track log) in the simulator (a "GPSin", if you will). My program currently does this by producing a MS Flight Video (.FSR) file which it then delivers to the simulator.

This seems to work OK, but the playback is a bit choppy, and there are some other problems which I'm hoping to solve by using FSUIPC.

Using the method you suggested above (e.g., "manipulating the six degrees of freedom" using FSUIPC), what can I expect in terms of performance? For instance, am I likely to see the smoothness I'm currently missing as the simulator "flies" through the LLAPBH values I set? How many values should I set per second for optimal performance (my underlying data stream typically represents one datum per second, but my program currently produces a linear transition for each parameter to achieve a desired "frame rate")? Also, I read something about needing to use "Slew" mode when setting LAT/LON in FSUIPC; this doesn't sound good - is this correct/any comments?

I'm also thinking about new things that I could do given the ability to "read" environmental cues from the simulator (as I could do with FSUIPC). For example, if I can get windspeed and direction then I can more accurately calculate heading (e.g. crab into the wind). Or perhaps more importantly, I could avoid "ground encounters" and other anomalies I'm currently experiencing due to not knowing the altitude of the ground at the current LAT/LON position (such as taking off from several feet underneath a runway, or banking during taxiing turns).

I'd appreciate any ideas from you about how I could best use FSUIPC to effect the best possible result for my purpose.

And, thanks for all of your support and for the great bridge to MSFS!

-- Marty

[Pete Dowson]

Using the method you suggested above (e.g., "manipulating the six degrees of freedom" using FSUIPC), what can I expect in terms of performance? For instance, am I likely to see the smoothness I'm currently missing as the simulator "flies" through the LLAPBH values I set? How many values should I set per second for optimal performance (my underlying data stream typically represents one datum per second, but my program currently produces a linear transition for each parameter to achieve a desired "frame rate")? Also, I read something about needing to use "Slew" mode when setting LAT/LON in FSUIPC; this doesn't sound good - is this correct/any comments?

Since I've never done anything like that I can't really say if you can get it perfectly smooth. With enough computer power I don't see why not -- a lot will depend on how much of the detail and so on you have switched on in FS.

For smoothest operation you want to be able to input just the right number of changes per second to match the "natural" FS frame rate. To start with I would set the FS Frame Rate Limiter to, say, 18 or 20 per second (18 is a natural figure as it is also the standard Windows timer tick second, used quite a lot in FS), then try to feed the data in at that rate. If you allow it to be adjustable you could try faster rates, or course.

With versions of FS before FS2004 there were only three ways of changing all 6 values:

1. slew mode

2. paused mode

3. what I call "stopped" mode (setting the Sim Rate to 0)

All these should be workable in FS2004 too, but in fact, as I think I say in the Guide, you can change them in normal flight mode now.

Bear in mind that if FS is actually simulating then it will be trying to change things as well, so you then cannot allow it to run faster than you -- hence the use of the frame rate limiter.

Regards,

Pete