Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!ucsd!nosc!helios.ee.lbl.gov!lll-tis!ames!amdahl!oliveb!amiga!jimm
From: jimm@amiga.UUCP (Jim Mackraz)
Newsgroups: comp.sys.amiga.tech
Subject: Re: WaitTOF in interlace mode
Message-ID: <2622@amiga.UUCP>
Date: 23 Jul 88 20:00:58 GMT
References: <4860@killer.DALLAS.TX.US> <2596@amiga.UUCP> <3379@cadnetix.COM>
Reply-To: jimm@cloyd.UUCP (Jim Mackraz)
Organization: Commodore-Amiga Inc, Los Gatos CA
Lines: 51

In article <3379@cadnetix.COM> childs@cadnetix.COM (David Childs) writes:
)In article <2596@amiga.UUCP> jimm@cloyd.UUCP (Jim Mackraz) writes:
)<In article <4860@killer.DALLAS.TX.US> ltf@killer.DALLAS.TX.US (Lance Franklin) writes:
)<)  Right now, I open
)<)a CUSTOMBITMAP window with two planes on the WorkBench, then allocate a
)<)bitmap with a single plane with it's address replicated in both plane pointers
)<)in the RastPort.Bitmap structure.  This allows me to have four color gadgets
)<)in the frame, but faster blits (thru a second RastPort structure pointing to
)<)the same single plane).                ^^^^^^^^^^^^^^^
)<
)<Nice idea, I think.  Actually, no.
)<
)<Don't forget: the actual number of bitplanes visible is determined by
)<the screen.  Superbitmaps, etc. are just metaphors, and not always 
)<particularly fast metaphors.
)<
)<Your trick would probably do everything twice, for both bitplanes,
)<whether the bitplanes were at the same address or not.  You need to lie
)<about either the BitMap.Depth or the RastPort.mask to get rendering
)<to only do one plane.
)
)I believe Lance was saying he uses a different RastPort structure with a depth
)of ONE point to the same single plane the other RastPort points to twice, and
)then uses the second different RastPort to do the blit.  If I'm wrong please
)tell me.  Why would it render everything twice if he used his second Rastport?
)I understand that the screen has 2 bitplanes, but if the Rastport has only one
)where would the second blit go?
)
)<)Thanks.....Lance
)<	jimm
)
)   David Childs               Internet: childs@cadnetix.COM

Well, I didn't see the key phrase 'with depth equal to one.'  My comments
apply to bitmaps with multiple pointers pointing to the same bitplane.

As we've both made clear, depth of 1 is the trick.

Maybe I don't see what the plans for the bitmap with multiplicity was.
It's perhaps a way of tricking Intuition rendering to restrict itself to
a single plane, but the more standard way would probably be the rastport
mask.  It depends on how you want to collapse 4 colors to 2, I guess.

Maybe Lance had it all figured out.

	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.