Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!ucsd!ucbvax!decwrl!mejac!gryphon!jdow
From: jdow@gryphon.CTS.COM (J. Dow)
Newsgroups: comp.sys.amiga
Subject: Re: graphics chips ideas
Message-ID: <5490@gryphon.CTS.COM>
Date: 12 Aug 88 07:09:10 GMT
References: <0Wz-V=Au8k-083IFce@andrew.cmu.edu>
Reply-To: jdow@gryphon.CTS.COM (J. Dow)
Organization: Trailing Edge Technology, Redondo Beach, CA
Lines: 34

In article <0Wz-V=Au8k-083IFce@andrew.cmu.edu> bader+@andrew.cmu.edu (Miles Bader) writes:
>Currently, as I understand it, in instances where you want a
>background to show through (like with sprites, or in dual-playfield
>mode), a particular color register indicates "see-through."
>
>I think a neat way to do it would to be eliminate the special
>behavior of that register, and add another 4 bits to ALL the color
>registers (for a total of 16 bits each), which would be "opaqueness":
>a value of 0 would mean "completely transparent," and a value of 15
>would mean completely opaque.  The color of a pixel would be
>(fg*op)+(bg*(15-op)) for each of red, blue and green, where op is the
>opaqueness, fg is the intensity of this layer, and bg is the
>intensity of the underlying layer.
>
Um, Miles, wanna tell me what the Amiga is going to use for bus bandwidth to do
all this? Hires 4 bitplanes currently burns ALL the CHIP ram bandwidth durning
the active portions of the frame. 4 more bitplanes MIGHT be possible if you go
to 32 bit buses in the Amiga. I kinda wish they would. We could well use that
added bandwidth. (And it'd be fun to listen to the HW vendors scream in 
anguish over the chaned bus yet again.  (I'm feeling nasty tonite!)

>-Miles


-- 
Sometimes a bird in the hand leaves a sticky deposit.
Perhaps it were best it remain there in the bush with the other one.

{@_@}
	jdow@bix (where else?)		Sometimes the dragon wins. Sometimes
	jdow@gryphon.CTS.COM		the knight. Does the fair maiden ever
	{backbone}!gryphon!jdow		win? Surely both the knight and dragon
					stink. Maybe the maiden should suicide?
					Better yet - she should get an Amiga and					quit playing with dragons and knights.