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From: peter@sugar.UUCP (Peter da Silva)
Newsgroups: comp.sys.amiga
Subject: Re: Double Buffering
Message-ID: <1102@sugar.UUCP>
Date: Sun, 22-Nov-87 12:58:52 EST
Article-I.D.: sugar.1102
Posted: Sun Nov 22 12:58:52 1987
Date-Received: Wed, 25-Nov-87 03:01:02 EST
References: <7768@steinmetz.steinmetz.UUCP> <1038@sugar.UUCP> <21733@ucbvax.BERKELEY.EDU>
Organization: Sugar Land UNIX - Houston, TX
Lines: 57
Keywords: double buffering, vertical retrace, screens

In article <21733@ucbvax.BERKELEY.EDU>, bryce@hoser.berkeley.edu (Bryce Nesbitt) writes:
> In article <1038@> peter@sugar.UUCP (Peter da Silva) writes:
> >Why don't you just set up two screens and use ScreenToFront and ScreenToBack
> >to flip them? 
> Peter da Silva, multitasking terrorist.

Yow! borrowing Stallman's terminology? Have a look at my Gauge program to see
some TRUE terror-tactics!

> This is quick, easy and  probably
> will be compatible in the future.

My main point.

> But it is also a dirty, ugly
> kludge that gives users headaches.  Try C= N or C= M on such a program.

Good point.

> Try dragging the screen.  YUCK!

Flip()
{
	MoveScreen(scr[!mine], 0, scr[mine]->TopEdge - scr[!mine]->TopEdge);
	ScreenToFront(scr[!mine]);
	mine = !mine;
}

> In the second case, post a "start animating" requester in *your*
> screen.  Or maybe one in each, come to think of it.  Still a 
> kludge.

Better than whatever Scult/Animate-3d does, though. And did you try dragging
Halfbright Hill, ever? Whetever you do should be attached to screens or
you'll see some REAL terror tactics!

(Still have no idea why Halfbright Hill did the stuff it did. An overscan
screen would have done the job fine.)

> Set the ViewPort->RasInfo->BitMap plane pointers to the
> "other" data then MakeScreen(Screen), RethinkDisplay().
> The problem with this is that it rebuilds the copperlists
> and that takes a while.  (Reference: WaveBench-1 in interlace :-)

Looks like it's not too bad an idea.

> A unique solution was used by Matt Dillon.  He had a two bitplane
> display for Wiredemo.  He draws into one plane at a time, setting
> the color registers to make that plane invisible at the time.
> Flopping the color registers is fast.

This is an all-time classic technique.

By the way, how do you get OUT of wiredemo?
-- 
-- Peter da Silva  `-_-'  ...!hoptoad!academ!uhnix1!sugar!peter
-- Disclaimer: These U aren't mere opinions... these are *values*.