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
