Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ucbvax!hplabs!well!ewhac
From: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Newsgroups: comp.sys.amiga
Subject: Re: Double Buffering
Keywords: copperlists, multitasking, interlace
Message-ID: <4748@well.UUCP>
Date: 15 Dec 87 23:35:11 GMT
References: <7768@steinmetz.steinmetz.UUCP> <782@mitsumi.UUCP> <812@rmi.UUCP>
Reply-To: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Organization: Claus Industries, Ltd.
Lines: 35

In article <812@rmi.UUCP> kkaempf@rmi.UUCP (Klaus Kaempf) writes:
:In article <782@mitsumi.UUCP> jimm@mitsumi.UUCP (Jim
:Mackraz) writes:
:: In article <7768@steinmetz.steinmetz.UUCP>
:: guilford@csv.rpi.edu (james d guilford) writes:
::: I am planning to write some animation-type software, and
::: so I looked up double buffering in the RKM. It suggested
::: that I create two screens and two sets of copper lists,
::: and then to flip screens, I just replace the copper list
::: pointers.
:
:Scan the copperlists (AND the intermediate copperlists!!!)
:for the MOVE instructions, that will install your bitplanes,
:and replace the arguments to these directly (Disable(), of
:course). You will also have to set up the "struct BitMap" in
:your ViewPort to reflect these new circumstances, because
:someone else might call "RemakeDisplay()". DO NOT assume a
:fixed layout of the copperlists! This one should be written
:in assembler.
:
:Hey Leo! Don't _you_ have a better idea 'bout this?
:
	Well, the procedure you just described (scanning Copper lists) is
precisely what ScrollVPort() does.

	For example code, look at my old display hack, "Ing".  It double-
buffers using ScrollVPort().  You can drag the screen, depth arrange it and
everything.  It does glitch a tiny bit, but that is largely dependent on the
Phase of The Moon.

_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
Leo L. Schwab -- The Guy in The Cape	ihnp4!ptsfa -\
 \_ -_		Recumbent Bikes:	      dual ---> !{well,unicom}!ewhac
O----^o	      The Only Way To Fly.	      hplabs / (pronounced "AE-wack")
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