On Tue, 23 Oct 2001, trasatti wrote:
> Thank you to all that answer to me.
>
> > > Otherwise, how to blit the captured mmap buffer (after processing it) onto the
>display, even without any XImage or with other functions than XShmPutImage.
> > >
> >
> > OpenGL provides an alternative method with glDrawPixels. But
> > I don't expect that to be much (if at all) faster than XShmPutImage.
> > I would guess that it's probably slower on most implmentations.
> >
>
> So isn't possible to "memcopy" or "xshmputimage" or anything else, the RGB mmapped
>buffer directly onto the X display?
Not in any portable way. You don't know the cliplist or anything.
Even if you did find out where the framebuffer was and map it you'd
don't know for certain where the window is and you don't know when
the server is VT switched away or when access to the framebuffer
is blocked (in some multihead configurations) and you'd need root
permissions to map the framebuffer anyhow. This kind of thing
shouldn't be done by clients.
OpenGL could do the copy data directly without a context switch.
It could even use the hardware to accelerate it if such features
were available. But I suspect that this path isn't very well
optimized in most OpenGL drivers, at least not in ones geared
towards video games.
Mark.
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