bobSamuels Posted October 11, 2004 Report Share Posted October 11, 2004 Hello! I have maybe a sensitive question for you: I am getting started with Flight Gear and am building a simulator built on that. However, I'm noticing that although the visual part of Flight Gear is well developed, and only getting better, it doesn't seem to be in the same level as MSFS. So what I was thinking of doing is using Flight Gear as my sim engine and using MSFS as the scenery engine. Have you heard of anyone who has done this before? Is this a bad idea? Am I allowed to do this under the GPL? Can WideFS handle this or would I have to hack the Flight Gear code to get it to output data in the correct format? Thanks in advance for any help you can give me! /Pat Link to comment Share on other sites More sharing options...
Pete Dowson Posted October 11, 2004 Report Share Posted October 11, 2004 So what I was thinking of doing is using Flight Gear as my sim engine and using MSFS as the scenery engine. Have you heard of anyone who has done this before? It's been done for quite a while for the Aerowinx 747 Precision Simulator (PS1). Look at the links on the right-hand side of the http://www.schiratti.com/dowson page -- those marked "(PS13)" should be relevant. Am I allowed to do this under the GPL? What's "the GPL"? Can WideFS handle this or would I have to hack the Flight Gear code to get it to output data in the correct format? WideFS and FSUIPC relate to Microsoft Flight simulator. I have absolutely no idea what "Flight Gear" is, but I am assuming it is nother flight simulator judging by your text. Nothing of mine is designed for anything but FS, you'd need to do your own programming for another sim. Regards Pete Link to comment Share on other sites More sharing options...
jcboliveira Posted October 17, 2004 Report Share Posted October 17, 2004 GPL means General Public License the most famous is the GNU GPL. For a list of licenses: http://www.gnu.org/licenses/license-listroduction Regards José Link to comment Share on other sites More sharing options...
Pete Dowson Posted October 17, 2004 Report Share Posted October 17, 2004 GPL means General Public License the most famous is the GNU GPL. Ah! So presumably this "Flight Gear" program is published under one of these, and the inquirer was wondering if linking it to FSUIPC would be against its license. Right? Looking at the link you quoted, I guess the question arises because of the business of "linking with non-free modules". That's an interesting one. Really, for freeware use in accessing FS internals, FSUIPC is a free module. There's a fee for commercial use only, but otherwise the interfacing aspects of FSUIPC are free. The user facilities should, in such cases, be regarded separately (indeed, I suppose they could, with some risk of inefficiency, be separated into a separate module, albeit with very close links to the other, and vice versa). Anyway, I hope the references to another successful implementation, that of PS1, was helpful to Pat. He's not been back yet to say. Regards, Pete Link to comment Share on other sites More sharing options...
Jamie Fox Posted October 20, 2004 Report Share Posted October 20, 2004 GPL means General Public License the most famous is the GNU GPL. I have never heard of any other GPL, although there are several other *PL licences. It would be confusing to refer to any other licence as GPL, although if one wishes to be precise, 'GNU GPL' removes the ambiguity. So what I was thinking of doing is using Flight Gear as my sim engine and using MSFS as the scenery engine. Have you heard of anyone who has done this before? I guess they probably have, although I haven't heard of it. Is this a bad idea? No, probably quite a good idea actually. Am I allowed to do this under the GPL? Yes, but see below. Can WideFS handle this or would I have to hack the Flight Gear code to get it to output data in the correct format? Yes and possibly yes. Really, for freeware use in accessing FS internals, FSUIPC is a free module. When the word 'free' is used in the GPL, it is a reference to freedom, not price. In this context FSUIPC itself is certainly non-free. Technical Issues You could do this using WideFS. Think of it something like this: Flightgear <-FlightGear IPC-> your program <-FSUIPC user library-> (<-WideFS optionally here->) MSFS I don't know what inter-process communication facilities are available in FlightGear. If there aren't any, you could either add some yourself. Alternatively you could integrate the program into FlightGear itself, subject to certain conditions. Legal Issues 1. If you modify parts of FlightGear, then you must either distribute those modifications under the GPL, else not at all. 2. If you wish to link your program directly into FlightGear then your program must also be licensed under the GPL. One of the most controversial parts of the GPL is what constitutes a 'derivative work'. The FSF's stance seems to be that static or dynamic linking counts as a derivative work, but other IPC mechanisms (such as sockets and, in my opinion only, the interface between FSUIPC user library and FSUIPC.dll) can be considered as independent. In any case, if you only want to distribute code that is yours, you can add a 'special exception' to the license text to explictly allow linking to FSUIPC-related stuff. Have a look on the FSF site for for 'special exception' and you should find what you're looking for. I hope that makes sense. I think I've gone on too long. Just one final important question for Pete: Is the FSUIPC_User.lib code public domain? I was under the impression that it is, but I can't find any notice in the code. (Public domain is taken to mean that all copyright holders have explictly disclaimed their copyright.) I guess it must be pretty close, as there are plenty of proprietary programs linking against it. Link to comment Share on other sites More sharing options...
Pete Dowson Posted October 21, 2004 Report Share Posted October 21, 2004 When the word 'free' is used in the GPL, it is a reference to freedom, not price. In this context FSUIPC itself is certainly non-free. Sorry, I don't understand this part. "Freedom" in the sense that it isn't imprisoned? Or freedom for people to use it and interface to it? Can you be a little more explicit, please? Is the FSUIPC_User.lib code public domain? I was under the impression that it is, but I can't find any notice in the code. Well, it's merely one way of writing code to interface to FSUIPC. It's almost exactly the same as the way things were interfaced to FS5IPC and FS6IPC beforehand -- that was the whole point, compatibility -- so if Adam's publication of how to do it was "public domain" then I guess this is. It is an illustration, an example, as well as being a short cut for those who aren't interested in fiddling about with the interface workings. The other language variants were all derived from this, independently, by other people, not me. I provided them all as a service, with their permission. I've no idea whether they would regard their work as public domain or not. Sorry, I guess I'm not cut out to be a solicitor (lawyer). Regards, Pete Link to comment Share on other sites More sharing options...
Jamie Fox Posted October 21, 2004 Report Share Posted October 21, 2004 The following is quoted from the Free Software Definition: We maintain this free software definition to show clearly what must be true about a particular software program for it to be considered free software. ``Free software'' is a matter of liberty, not price. To understand the concept, you should think of ``free'' as in ``free speech,'' not as in ``free beer.'' Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software. More precisely, it refers to four kinds of freedom, for the users of the software: * The freedom to run the program, for any purpose (freedom 0). * The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this. * The freedom to redistribute copies so you can help your neighbor (freedom 2). * The freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this. Surely you must be familiar with at least one of the following words: GNU, BSD, Apache, Debian, Linux, Mozilla, KDE, GNOME. No? Link to comment Share on other sites More sharing options...
tuomas Posted October 21, 2004 Report Share Posted October 21, 2004 GPL means General Public License the most famous is the GNU GPL. I have never heard of any other GPL, although there are several other *PL licences. It would be confusing to refer to any other licence as GPL, although if one wishes to be precise, 'GNU GPL' removes the ambiguity. GPL as in Glider Pilots License, anyone? 8) As for the licensing issues, I bet the flightgear authors are more familiar wiht the stuff and might be able to answer you better. //Tuomas Link to comment Share on other sites More sharing options...
Pete Dowson Posted October 21, 2004 Report Share Posted October 21, 2004 Surely you must be familiar with at least one of the following words: GNU, BSD, Apache, Debian, Linux, Mozilla, KDE, GNOME. No? Actually, I have heard of "No", but I don't seem to be all that good at using it I'm afraid! :) Regards, Pete Link to comment Share on other sites More sharing options...
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