On Thu, 9 May 2013 14:57:21 +0000 (UTC), castle...@comcast.net wrote in message <142462582.1782424.1368111441180.javamail.r...@sz0139a.emeryville.ca.mail.comcast.net>:
> Hi, > > Thanks to Jan Comans I've been able to sync the 3D clouds across > three instances of fgfs running on a multi-core machine. This, in > turn, provides for some very respectable frame rates of 40 to 50 fps > per core with a three projector system with older generation Nvidia > boards ( GT430 and GT440 ) on a 64bit I5 machine. The visuals will > be just awesome once the collimated display is completed later this > year. > > However, all is not perfect in simworld. Since each CPU starts and > runs independently there is a skew in sim time for each core and AI > trsffic is just not usable with models "disappearing" into the screen > edge and then showing up at the adjacent screen boundary a few > seconds later. > > One possible solution is to start with the sim clock "frozen" and > once all instances have booted and initialized send out a control > packet via the native-ctrls protocols and unfreeze the clocks. A > better solution would be to use the fdm packets to start the clocks > since that protocol is already being used to sync the fdm slaves to > the master. This network method will still have a bit of latency; > probably the best solution is to have a freeze flag in a portion of > shared memory accessed by all cores and then clear the freeze state > once you are ready to run. This has an additional advantage of be > able to stop and start all instances with microsecond accuracy. > > Just wondering if anyone has messed in this area and has some > info/data on such things as to how much latency is tolerable before > the AI models start "breaking up" across screen boundaries? Is there > clock drift due to variations in delta t's for each CPU/GPU set based > on rendering times for each screen? Any need to send out a local sim > time standard to adjust for any drift and keep things in sync? > > Any thoughts, comments, suggestions would be appreciated and will > earn credits for sim time if you happen to be passing through the > Colorado Springs area. ;-) > > Cheers > Jack ..the ntp time server gives you too much skewed time? On a lan, you should have your box clocks within milliseconds from each other. Details in: http://www.ntp.org/ and http://en.wikipedia.org/wiki/Network_Time_Protocol ..install a ntp server on your master machine and ntp clients on your other machines. Or, set up a ntp server hardware box and run ntp clients on all your FG boxes, to bring them closer. You want the same time error on all your ntp clients. -- ..med vennlig hilsen = with Kind Regards from Arnt Karlsen ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. This 200-page book is written by three acclaimed leaders in the field. The early access version is available now. Download your free book today! http://p.sf.net/sfu/neotech_d2d_may _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
