Re: APP draw
Hansong Zhang (zhangh++at++cs.unc.edu)
Mon, 24 Jun 1996 12:47:52 -0400 (EDT)
>
> > What should I do in order to be able to draw in the APP process?
> > The pfChannel man pages say "... only the draw process is attached
> > to a graphics context." How (if possible) to make APP share this
> > graphics context and the window DRAW creates? The aim is to be
> > able to draw from APP with no switching overhead.
> >
> > I know two processes cannot draw to the same window at the same time,
> > but suppose I can do exclusion properly...
>
> Just use a double buffer in shared memory. Put the needed info in to draw
> the stuff you want and let a post-draw function draw it.
> While App is filling one buffer Draw is looking in the other buffer and draws.
> If you know that App can fill in the buffer before the drawing of the scene
> is complete you can use only a single buffer, use a flag variable to signal
> Draw that the data is valid in case there is very little to draw in the scene.
>
> Mario
Mario, thanks for your reply! Sorry for not having made this clear, but
by "draw in the APP process" I mean real hardware graphics, but not building
something like a display list for DRAW process to consume later.
Hansong
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