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From: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Newsgroups: comp.sys.amiga
Subject: Re: Double Buffering
Message-ID: <4414@well.UUCP>
Date: Mon, 9-Nov-87 18:51:38 EST
Article-I.D.: well.4414
Posted: Mon Nov  9 18:51:38 1987
Date-Received: Thu, 12-Nov-87 06:21:46 EST
References: <7768@steinmetz.steinmetz.UUCP>
Reply-To: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Organization: Apple Computer:  We own a Cray; we *must* know what we're doing.
Lines: 25
Keywords: double buffering, vertical retrace, screens

In article <7768@steinmetz.steinmetz.UUCP> guilford@csv.rpi.edu (james d guilford) writes:
:My question is whether I still have to sync with the vertical retrace.
:It seems to me that even after updating the copper-list pointers, they
:will not be used until the next scan begins. Thus it would not be safe
:to start rendering into the other screen until after at least one
:vertical blanking period. Is this right?
:
	Yup.  After finishing rendering into the off-screen bitmap, you'd
LoadView() it (or ScrrenToFront() it), then call WaitTOF().  When WaitTOF()
comes back, the system will be displaying your other view.

:I am thinking of creating an interrupt handler on the vertical
:blanking list which would have a private message port. When I change
:the copper list points, I would send it a message. When the vertical
:retrace occurs, it would reply to the message. When I see the reply, I
:know it is safe to start rendering the next screen. Is this the best
:way to go?
:
	Seems needlessly complicated to me.  WaitTOF()ing is much easier.

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Leo L. Schwab -- The Guy in The Cape	ihnp4!ptsfa -\
 \_ -_		Recumbent Bikes:	      dual ---> !{well,unicom}!ewhac
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