I am currently using the main thread and it is producing these incorrect images. I have not even multithreaded it yet. When I do I will only be threading the writting of the image.
Seamus On Wed, 25 Feb 2004, Frederic Bouvier wrote: > Seamus Thomas Carroll wrote: > > > Hi, > > > > I am trying to save images from flightgear to a file or database without > > explicitly using the gui. For a test of current capability I am > > calling fgDumpSnapShot every second but I am finding it produces saved > > images that are completely white or contain corruption, yet other images > are > > saved as expected. The only change I mode to fgDumpSnapShot is I > commented > > out "mkDialog (message.c_str());". > > > > I am trying to implement a threaded image saver so that it does not > > cause pauses in the simulator that continiously saves images over a > > specified interval. > > If you are doing snapshot in another thread, you must be sure that the > buffer you are dumping is not being cleared, swapped or written at the > same time by the main thread. > > Generally, people think it is not possible to call OpenGL API from > multiple thread at the same time because of the state oriented nature > of OpenGL. The arguments seem reasonable and I take them for true, so I > never experiment myself. > > In theory, it should be possible to dump the front buffer while the back > buffer is updated, but fgDumpSnapShot should be rewriten to avoid calling > fgInitVisual, fgReshape or fgRenderFrame in two different threads. > This imply also some sort of synchronization to avoid doing a SwapBuffer > during the ReadPixels call. > > > I think I understand how fgDumpSnapShot works and was going to use it as > > an example but it only seems to produce correct results when called > > through the gui. > > Yes, in the main thread. > > > Should I be using another funtion as an example? > > I would look at sg_glDumpWindow and take the code portion that > write to the file from fgDumpSnapShot. > > -Fred > > > > _______________________________________________ > Flightgear-devel mailing list > [EMAIL PROTECTED] > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
