NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/sys/amiga/programmer/942

Internet Message Format | 1996-08-05 | 3.7 KB

Path: informatik.tu-muenchen.de!fischerj
From: [e-mail] (Juergen "Rally" Fischer)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: C2P
Date: 12 Jan 1996 19:53:30 GMT
Organization: Technische Universitaet Muenchen, Germany
Distribution: world
Message-ID: <4d6e7q$[e-mail]>
References: <4cj57f$[e-mail]> <4cjmsk$[e-mail]> <[e-mail]> <4cskrt$[e-mail]> <4d16bt$[e-mail]> <4d27jf$[e-mail]>
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In article <4d27jf$[e-mail]>, [e-mail] (Sam Yee) writes:
|> Organization: Simon Fraser University
|> Lines: 41
|> Message-ID: <4d27jf$[e-mail]>
|> References: <4cj57f$[e-mail]> <4cjmsk$[e-mail]> <[e-mail]> <4cskrt$[e-mail]> <4d16bt$[e-mail]>
|> NNTP-Posting-Host: fraser.sfu.ca
|> X-Newsreader: NN version 6.5.0 #5 (NOV)
|>
|>
|> (please e-mail to [e-mail])
|>
|> [e-mail] (Juergen "Rally" Fischer) writes:
|>
|>
|> >|> Are you using HAM mode?  You can get excellent speed only updating the lower
|> >|> four bitplanes and interlacing lores screens, alternating odd/even chunky
|> >|> pixels.
|>
|> >cool, have you done a demo with your idea ?
|>
|> Not yet.  Have no access to an Amiga right now.  The basic idea is to use
|> 16-bit chunky pixels in R4G4B4B4R3G3B3B3R2G2B2B2R1G1B1B1R0G0B0B0 format

what about a very dirty 1x1 mode:

R0G1B2R4G5B6

;) only one component of a pixel is overtaken, but not the one needed most
but just random (well, R,G and B cyclic).

Anyone knows how picutres look after this kind of conversion ?


|> and do a two pass (4- and 8-bit) C2P on the lower four bitplanes.  The upper
|> two bitplanes in HAM mode are set to display RGBBRGBB... If you use
|> movep.w to output your chunky words, you don't need to do the 8-bit pass,
|> if you do the 4-bit with blitter.
|> This gives you a 16-bit 2x2/2x1 truecolour mode on all Amigas.  Also you need to
|> setup the copper to swap screens every 1/60th or 1/50th of a second, and shift
|> the screen display right two pixels to fill in the odd/even pixels.
|> You can do the same with an interlaced screen, but the non-interlaced
|> flicker version looks cleaner (tried a dpaint anim using the same framerate
|> and it looks better than interlaced).

you mean the pixels get flicker-mixed ? theoretical you'd need a mask, but
maybe this looks better.

|>
|> And if you have the luxury of an AGA machine, you can set up a hires HAM
|> screen (640x100 or 640x200) and get a 160x100 or 160x200 display without
|> the need to flicker screens back and forth.

my picture viewer uses a render method, that just looks which component is
to needed updated (the biggest difference to the new wannabe-24bit value).
looks good for photos, quite quick (seen from speed of picture viewers,
which include palette for rendering).

With using tables and a PPC maybe a way for 24bit games ?

|>
|> >if the cpu is quick enough, and the renderer is dirty enough to get conversion
|> >for free ;) then you should even be able to copy a 1x1 screen in 1/2 frame! =:o
|>
|> >but maybe you got to wait for PPC to get it for free ;)
|>
|> >would be especially interesting for all A3000 users! (quick cpu but no AGA)
|>
|>
|> [e-mail]
|> ------------------
|> "Let he who has no sword sell his cloak and buy one." - Jesus, Luke 22:36
|>
------------------------------------------------------------------------
   [e-mail] (Juergen "Rally" Fischer)   =:)