On Nov 19, 2007 9:25 AM, Ákos Maróy <[EMAIL PROTECTED]> wrote: > Paul Martz wrote: > > 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. > > but does this mean that if I call rendering blocks unti the next vsync > clock tick?
OpenGL drivers have a FIFO, your app fills the fifo with tokens and data, at the end of the frame you send in a swap buffers token and this goes into the FIFO with everything else. Normally the swap buffers call itself doesn't block (although some implementations do this), but the FIFO itself can only be cleared at the rate for one swap buffers call per frame so it'll fill and once filled up it will effectively block until previous frame was begun dispatching. The driver may allow several frames worth data in the fifo before block, this is driver dependent, and also dependent on just how data you have to pass to OpenGL- if you have massive models the CPU will be block on the FIFO right on the same frame rather than more than one frame begin backed in the FIFO. The end result of this is simpler though - put vsync on, and your frame loop will block and should iddle while its waiting for the FIFO to begin accepting new data. Some OpenGL drivers have been known to CPU resources when waiting rather than idling - ATI drivers were doing this for a while, but I believe this has now been fixed. Robert. _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
