If the following is true,then i think i cannot get a fps more than 150 on the 85Mhz monitor.
but in single buffer mode i can get a 500 fps,how can that be?
this is from SGI :
"Smooth animation also requires double buffering. In double buffering, one framebuffer holds the current frame, which is scanned out to the monitor by video hardware, while the rendering hardware is drawing into a second buffer that is not visible. When the new framebuffer is ready to be displayed, the system swaps the buffers. On hardware implementations, the system must wait until the next vertical retrace period between raster scans to swap the buffers, so that each raster scan displays an entire stable frame, rather than parts of two or more frames.
Frame rates must be integral multiples of the screen refresh time, which is 16.7 msec (milliseconds) for a 60-Hz monitor. If the draw time for a frame is slightly longer than the time for n raster scans, the system waits until the n+1st vertical retrace before swapping buffers and allowing drawing to continue, so the total frame time is (n+1)*16.7 msec.