• Which the release of FS2020 we see an explosition of activity on the forun and of course we are very happy to see this. But having all questions about FS2020 in one forum becomes a bit messy. So therefore we would like to ask you all to use the following guidelines when posting your questions:

    • Tag FS2020 specific questions with the MSFS2020 tag.
    • Questions about making 3D assets can be posted in the 3D asset design forum. Either post them in the subforum of the modelling tool you use or in the general forum if they are general.
    • Questions about aircraft design can be posted in the Aircraft design forum
    • Questions about airport design can be posted in the FS2020 airport design forum. Once airport development tools have been updated for FS2020 you can post tool speciifc questions in the subforums of those tools as well of course.
    • Questions about terrain design can be posted in the FS2020 terrain design forum.
    • Questions about SimConnect can be posted in the SimConnect forum.

    Any other question that is not specific to an aspect of development or tool can be posted in the General chat forum.

    By following these guidelines we make sure that the forums remain easy to read for everybody and also that the right people can find your post to answer it.

BGL file format specs?

P

Philstix

Messages
3
Country
australia
Hi,

Can anyone point me to an up-to-date document detailing the BGL file format specs?

I'm trying to write a flight planning utility in C++, and I want the program to extract data from BGL files.

There are several utilities that extract this info, so I know it's possible. I don't want to use a utility to get this data, I want to do it myself programmatically.

I've read the pdf by Winfried Orthmann, but it's very incomplete and it contains errors.

I've been plodding through the C source of Alessandro G. Antonini's BGLXML, but it doesn't explain the BGL file structure in any way.

I've been searching for days, and I've seen a lot of comments in various discussion groups where people talk about the BGL specs as if they were readily available, but they must be hiding because I can't find them.

Thanks for any help you can give before my head explodes.

Phil

PS Are the links in the Download section supposed to be dead?
 
Phil

If you have the pdf from Winfried and access to the source for BglXml then you have everything that is available. Clearly it has to be said that decompiling the proprietary format of bgl files is neither supported nor condoned by ACES.

You say the document from Winfried is very incomplete - that is not my impression - what area of the Bgl format do you think is not covered? Are you working in FSX or FS9??
 
Thanks for the quick reply.

I'm working with FS2004 bgl files.

The pdf I have is 'New BGL File structure' by Winfried Orthmann, with a file creation date of 6 March 2004. Perhaps there's a more recent version, but that's the latest one I could find.

There are quite a few data fields in the pdf listed as 'unknown', for example the last DWORD of the fixed part of the Airport record. The source for BGLXML indicates that that field is for the airport facilities data.

I've written a preliminary program to see how much airport data I can get by parsing a bgl using Orthmann's info. I must be doing something wrong because the bgl file contains 8 airports but I run out of Airport records after 3 iterations. AFCAD and BGLXML find all 8, so I suppose I'll have to step through the source one line at a time to work out the underlying process.

<wishful thinking mode on>
If only someone like Alessandro Antonini (the author of BGLXML) would release the bgl format specs he's discovered so newbies didn't have to reinvent the wheel.
Better yet, if Microsoft would publish the specs - I know it's proprietary, but I can't see how it would disadvantage them in any way to do so.
<wishful thinking mode off>

Thanks,

Phil
 
Phil

I do not know if you have looked at SDE Test App available from my website. This will decode both FS9 and FSX Bgl files. It has a mode that mimics the Bgl Format so that you can see how the file is made up. SDE uses the information provided by Winfried and is pretty much complete in extracting the information. Generally if Winfried says something has an unknown purpose then it either does or it does not do anything useful. There are a number of areas of the file that contain information that is either redundant or do not seem to do anything.

I am sure you will understand that there is a difference between understanding the format and writing code to extract information from it correctly. Itsounds like you have not gotten your extraction logic to work correctly yet. Writing a decompiler is not a trivial exercise. It took 6 months to develop SDE and it is still not 100% :)

Microsoft won't ever release the format of bgl files as far as I can see. Certainly the format is, or is based on formats that have third party copyright in any case so even if they wanted to they would not be able to. The best I hope for is that they provide a utility to generate xml from the bgl file. The xml is an open format and it would save us all a lot of trouble and still protect the internal format.
 
Thanks for the pointer to SDE. No, I haven't tried it yet. I've seen a few oblique references to it but none of them included a web address.

It sounds like I've got all of the available resources for bgl data extraction - my hat's off to those who have worked out the bgl format. I'm having a hard enough time even with their assistance. I don't know how they persisted through what must have been an exhaustive process of trial and error.

Thanks again for your help.
 
There is an SDE Forum here - SDE stands for Scenery Design Engine. Any problems feel free to post there. SDE TestApp is on AVSIM as well as www.scruffyduckScenery.co.uk

The work, as you say, is the result of a lot of time and effort of a lot of people over many years :):)
 
You must log in or register to reply here.
Back
Top