[...] > > IIRC Matrox cards have a way of making a single framebuffer (with > > xinerama hints) that appears on two monitors. That way you should > > get 3d accel on both displays. > > ATI has something similar, but their drivers don't seem to work with > Xinerama the normal way. It (sort of) works though, and as long as I > don't try to throw extra cards in the mix, I can have two independent > desktops (separate buffers, separate pixel formats etc) and still run > OpenGL on both.
Most (all?) hardware will support this (and all should). > There is another mode, where a single buffer forms a big desktop, of > which each RAMDAC displays a part. Seems like stupid driver > limitations restrict this mode to using the same resolution for both > heads, but I'm not sure. It is to be expected that a single rendering context has only one framebuffer configuration. "Consumer" hardware does not have a per pixel framebuffer configuration stored in the framebuffer together with the color (and possibly clipping) data; a rendering operation expects a single config. --ms
