True Double buffering

Can somebody bring me some light on the topic of true double in Linux (using XFree86 4,
Debian and GeForce2 GO - applies to other nvidia cards as well).

With True doublebuffering I refer to actual having two buffers and the one displayed is determined by a pointer or ID selection of current hardware overlay or bitplanes in the framebuffer.

All my tests on nVidia cards (so far) just gives me an offscreen backbuffer which content is COPIED to the frontbuffers window upon glSwapBuffer(), you can get it synchronized with vertical blanking, but it doesn’t help
if the screen is large enought such that
copying takes longer than the blanking time.
I haven’t been able to get it to work with
the fullscreen modes available in GLFW and GLX.

Is this a hardware problem, a driver problem or a XFree/GLX problem. On SGI hardware you
get it without asking :wink: (I haven’t tried
Quadro cards yet…) If this is a hardware issue, which cards support true double buffering in Linux?

You can easily test this with just drawing two different frames and then without calling glClearBuffer swap the buffers. With true double buffering you will see flickering,
with buffer copying you’ll just see a static image since the same backbuffer is copied to the frontbuffer every frame.

thanks in advance for any light on this matter

/ Patric

This topic was automatically closed 183 days after the last reply. New replies are no longer allowed.