I have a problem with 2 independent view windows getting out of sync in a multi-channel system. Bear with me while I explain the configuration.
My current test system is one machine with 2 nVidia Quadro FX 4600 graphics cards. These cards are genlocked with the GSync2 option card. Each video card renders one half of a video frame which is then combined in the display hardware. My test scene is nothing but a spinning cube with 5 black faces and 1 white face. Each frame the cube is rotated 90 degrees showing 3 frames of black and 1 frame of white. GL is synced to VBLANK with the __GL_SYNC_TO_VBLANK environment variable. The behavior I'm seeing is when the program first starts the top and bottom half are in perfect sync. What is displayed is 3 frames of black and 1 frame of white producing a seizure-enducing strobe effect. However, after a short period of time (5-10 seconds), the bottom half (second video card) is 1 frame behind the top half. Visually you see the top half strobe slightly before the bottom half (verified with light sensors and a scope). The CPU load is very low (extremely simple scene). I am running in SIngleThreaded mode, and the threading mode doesn't seem to effect the problem. I have had this same problem where the two graphics cards were split across two different machines (2 computers, 2 graphics cards, genlocked with gsync2). In the scene, you will see the two halves looking as they should then after a while you'll see the two halves torn by 1 frame, then after a while they appear to re-sync back up (somewhat dependent on scene content). But while they are split, the system still runs at 60Hz so it is not in a constant overload condition. I believe the problem may lie in the rendering pipeline on the graphics card, and I need to figure out how to keep multiple pipelines in sync with each other. Has anyone else had this problem or knows what I can do to address this synchronization problem? Thank you John
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