On Thu, 1 Jan 2004, Stanko Juzbasic wrote:
> Hello,
>
> I am trying to convince Apple for quite a number of months to include
> Overlay visuals' support in their X11 server.
>
> Does xfree86 standard allow for overlay visual planes, or this feature
> only belongs to commercial X11 servers (such as the one in the SGI
> visualization workstations)?
A few XFree86 drivers support overlay visuals (overlay planes as in
XAllocColorPlanes are a different feature), but the thread
http://marc.theaimsgroup.com/?l=xfree-xpert&m=101506941016681&w=2
suggests that XFree86 OpenGL doesn't support the level attribute.
The reason that only a few drivers (mga and glint are the most
significant) support overlay visuals is that most hardware doesn't have
framebuffers with overlay bits in each pixel.
In particular (at least last time I looked) the Radeon and nVidia chips
didn't have the sort of framebuffer which would allow us to reuse the
code used by the mga and glint drivers. Thus Apple may not have the
hardware which would make adding the feature easy.
I'm not saying that video or texture overlays couldn't be used to
implement GLX Overlay Visuals, but we have never considered trying.
--
Andrew C. Aitchison Cambridge
[EMAIL PROTECTED]
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