Hi Chris, I work on an OpenSceneGraph-based image generator for the Federal Aviation Administration that is built on the CIGI protocol. Like you, we originally started from MPV and worked from there. Thankfully we threw all that code away and started from scratch.
I don't know how much has changed in MPV in the past five years... Maybe it's a great, well-engineered piece of software now! But if it's like what I remember, I'd only use it as a reference on CIGI concepts, not on how to integrate OSG into a CIGI application. It wasn't designed for multithreading, it was originally built for OSG 0.91, and it uses a library called osgSDL to handle Windowing, "threading", and user input... Which makes using any modern OSG code/examples (which expect an osgViewer/osgGA base) problematic to say the least. Also, if you're serious about CIGI support, you may need to roll your own CIGI library. I haven't looked at the 3.3.3 version of CCL, but when it finally became apparent that our wrapper code around CCL 3.3.2 was rivaling the size of CCL itself, we ended up rewriting it from scratch. Again, it's a good solution for teaching you the concepts, but I think it's really best as a reference implementation and not practical for production use... May I ask why you're working on adding a CIGI interface to FlightGear? I'm only curious because we keep asking ourselves why we stuck with CIGI all these years, as no one else actually seems to use it! Any other vendors we deal with always go "Well, yeah, you CAN use CIGI with our stuff... But it'd really be better if you used our API instead!" And then when you look at their CIGI support, they usually have just wrapped their proprietary packets in CIGI custom packets... Bleh. But if this hasn't thoroughly discouraged you yet... Well, I'm not sure I have any good news for you, really. You're going to find that SO MUCH of CIGI is either incredibly ambiguous or 'implementation defined', that you're going to have trouble writing a general-purpose CIGI wrapper. If you're willing to get more specific, I think a useful area for you to work on is handling EntityCtrl packets at the very least, to add/move/delete entities to a scene graph. That's (to me) the really key/useful feature exposed by CIGI, and is probably the most well-defined part of the protocol. It'll also be your first real taste of how CIGI gets you most of the way, as you'll have to provide an out-of-band way to map entity types to model files, and also a way to let a user specify the coordinate system transform from the WGS84 ellipsoid to their database coordinates. Oh, and CIGI optionally lets you specify a custom ellipsoid, too. I'd save some sanity and leave that particular feature in the "not supported" column. :) After that... Extending osgGA::NodeTrackerManipulator to follow the Ownship entity in your scene graph would be a good step towards having a functional image generator, if that's what you're aiming for. If you have any specific questions, feel free to ping me and I'll be happy to share the dubious benefits of five years of working on your problem with you. But if you're looking for general advice on implementing CIGI in OSG... Well... In one word: Don't. In slightly more words: Think very hard as to why you're doing it, and what the likelihood is you'll actually ever integrate your solution with a DIFFERENT system that uses CIGI... And is using a compatible version of CIGI... And made the same (or similar enough) choices about the ambiguous or implementation defined features... Good luck. -Chris B On Fri, May 24, 2013 at 5:26 PM, Chris Calef <[email protected]> wrote: > Hi, > > I'm new to OSG, coming in from the direction of FlightGear, but I'm here > primarily because I am interested in implementing a CIGI interface to > FlightGear, and would like to put as much of this work as possible into an > OSG module in order to make it useful to the larger OSG community and not > only FlightGear developers. > > I have read the conversations about doing this from several years ago, but > have not found any recent discussion or located any available code drops. > I have downloaded the MPV example from CIGI at sourceforge, which is based > on OSG, and that is quite helpful, but I wanted to introduce myself here > and see if anyone can catch me up on any other existing work in this > direction, or give me advice about where to start. > > Much of the CIGI interface is dedicated to higher order simulation > functions (ie celestial bodies, ocean conditions, aircraft controls) which > are probably too specific to implement at the OSG layer, but I'd like to > make at least a virtual wrapper in OSG which could be inherited by > FlightGear and other OSG based projects, each of which could determine on > its own which functions to support, and how to support them. > > Any pointers would be welcome. I am applying for funding for this project > in one week, so the more information I can gather before then the better. > > Thanks for all your efforts! > > Chris Calef, CTO > BrokeAss Games, LLC > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > >
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