> Robert Osfield wrote: > > As long as vsync is on, as it should almost should be then the CPU > > load shouldn't be overwhelming with a standard frame loop. > > you mentioned vsync several times in this discussion. can you > elaborate, how this is turned on?
Vsync is usually on by default, can be toggled on or off by some driver options, and can also sometimes be toggled by OpenGL extensions. CRT monitors paint the screen with an electron gun at typically 60 times a second. After each full screen paint, the electron gun moves back to the start position, often called "vblank". When vsync is enabled, your back buffer is swapped to your front (displayed) buffer during vblank. This is usually what you want; if the buffer was swapped while the electron gun was actively painting the display, then the displayed image (for that 1/60th of a second) would contain part of one frame and part of another. This is often referred to as "image tearing" and is usually avoided by enabling vsync. You usually want to disable vsync when measuring performance. If vsync is enabled, your frame rate is locked to some multiple of 60, such as 60, 30, 15, etc, which prevents you from obtaining an accurate performance measurement. When not measuring performance, you usually want vsync enabled to maintain image quality and eliminate tearing. Paul Martz Skew Matrix Software LLC http://www.skew-matrix.com 303 859 9466 _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
