Path: chuka.playstation.co.uk!news
From: Luca Cappellini <Luca.Cappellini@infores.com>
Newsgroups: scee.yaroze.programming.2d_graphics
Subject: Re: Active Buffer Question Please Respond
Date: Wed, 21 Jan 1998 14:03:02 +0100
Organization: PlayStation Net Yaroze (SCEE)
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Message-ID: <34C5F206.70F55525@infores.com>
References: <34C35011.7F79BE6D@infores.com> <01bd25bd$a6cf6be0$6c0b0a0a@newcastle.twowaytv.co.uk>
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Thanks for the responce but that was not what i was asking, only a my language
problem.

I think i understtod by myself, if that the GsGetActiveBuff does not return
the actual drawing buffer but the actual display one for that reason i can
start clearing the OT and load it with other things because it is already
passed throught the DMA channels is that right ?

CRAIG GRAHAM wrote:

> Luca Cappellini <Luca.Cappellini@infores.com> wrote in article
> <34C35011.7F79BE6D@infores.com>...
> > WHY you call GsSwapDispBuff that if i well understood swap the Draw buff
> > with the Disp buff  and than you run GsSortClear (if needed) and the
> > GsDrawOt that should be the command that do the real drawing. In that
> > way is not true that i'm drawing when the display of that buffer is
> > displaing, in other terms why we do the GsSwapDispBuff before the
> > GsDrawOt and not after ?????
>
> We start here (in the middle of drawing something), Buffer1 is visible,
> buffer2 is the drawing buffer:
>
> +------------+
> |  Buffer1  |  <----Displaying this buffer
> +------------+
> |  Buffer2  |  <----Drawing on this buffer
> +------------+
>
> We then call DrawSync() - this waits for the Draw op to complete.
>
> +------------+
> |  Buffer1  |  <----Still displaying this buffer
> +------------+
> |  Buffer2  |  <----Ready to display, but not visible yet
> +------------+
>
> Call GsSwapDispBuff():
>
> +------------+
> |  Buffer1  |  <----This is the old screen, now setup to be drawn on
> +------------+
> |  Buffer2  |  <----Now displaying this buffer (after DrawSync(), we know
> it's setup)
> +------------+
>
> Call GsDrawOt(), this will draw on Buffer1 (as this is the one which is no
> longer visible).
>
> > Luca
>
> Craig.