Path: utzoo!attcan!uunet!super!udel!gatech!ncar!ames!oliveb!amiga!jimm
From: jimm@amiga.UUCP (Jim Mackraz)
Newsgroups: comp.sys.amiga.tech
Subject: Re: MINTERM_SWAP?
Keywords: MINTERM graphics how
Message-ID: <3180@amiga.UUCP>
Date: 12 Dec 88 20:07:50 GMT
References: <1576@nmtsun.nmt.edu> <1946@imagine.PAWL.RPI.EDU>
Reply-To: jimm@cloyd.UUCP (Jim Mackraz)
Organization: Commodore-Amiga Inc, Los Gatos CA
Lines: 26

In article <1946@imagine.PAWL.RPI.EDU> guilford@turing.cs.rpi.edu (Jim Guilford) writes:
)In article <1576@nmtsun.nmt.edu> wbnsnsr@nmtsun.nmt.edu (William Norris) writes:
)>Is there a simple way to swap two bitmaps without a third temporary bitmap?
)>
)>I've looked over the MINTERMS, but none seem to do the trick.  How come
)>the lower nibble in the MINTERM is always 0?  If 0xC0 is a copy, shouldn't
)>0xCC be a swap?
)>
)>William B. Norris IV                               |\\ ///  l'Amiga peut 

Clearly, the blitter can't swap on a single blit, since there is only one
destination channel (it can only change one region at a time).

So, you can use the old "triple XOR trick", which JimG describes.

Or, if you can figure out how it works, you can use SwapBitsRastPortClipRect().
There are some alignment issues, but they are probably unavoidable.
Anyway, this function is used to bring up/down menus.

	jimm

-- 
	Jim Mackraz, I and I Computing	  
	amiga!jimm	BIX:jmackraz
Opinions are my own.  Comments regarding the Amiga operating system, and
all others, are not to be taken as Commodore official policy.