> On Wed, 18 Jun 2003, Alan Hourihane wrote: > > Use a shadow framebuffer and you only have to implement one function, which > > is how the framebuffer is refreshed.
On Wed, 18 Jun 2003, Dominic Duval wrote: > Unfortunately, the piece of garbage I'm using as a display controler runs > at a very low frame > rate (in the order of 2-3 fps), so I was actually hoping to find a better > solution, so that I could benefit from the various X optimizations. > > Just refreshing the frame buffer with the content of the shadow > framebuffer will limit the performance quite a lot, considering that > the system is also pretty slow (400MHz XScale). Misleading word "refreshed". With a shadow framebuffer, the one function you would write would be given a rectangle of the shadow buffer that needed repainting, and you are expected to copy that rectangle into the real framebuffer. I don't remember the details, but this will be called when the server thinks a group of drawing commands have been collected, but often enough that video refreshes wont be missed. You shouldn't find that it is trying to draw into the same rectangles many time in a single refresh, so (IIRC) for a 400MHz Pentium and a graphics card with slow memory (say an ISA VGA card from the days when 256 color VGA was a big deal), displaying at say 60Hz refresh, you would find that using a shadow framebuffer was faster than writing directly to the card. -- Andrew C Aitchison _______________________________________________ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
