Re: APP draw

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Veraart (rioj7++at++fel.tno.nl)
Mon, 24 Jun 1996 11:02:02 +0200 (MET DST)

> 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
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