NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/comp/sys/atari/st/21193

Text File | 1993-01-28 | 2.9 KB | 49 lines

Newsgroups: comp.sys.atari.st
Path: sparky!uunet!inmos!fulcrum!bham!warwick!pavo.csi.cam.ac.uk!cpb1001
From: [e-mail] (C.P. Brown)
Subject: Re: A1200 versus Falcon 030 once again (FAQ?)
Message-ID: <[e-mail]>
Sender: [e-mail] (C.P. Brown)
Nntp-Posting-Host: stonea.cl.cam.ac.uk
Organization: U of Cambridge Computer Lab, UK
References: <[e-mail]> <[e-mail]> <[e-mail]> <[e-mail]>
Date: Thu, 28 Jan 1993 13:29:18 GMT
Lines: 36

In article <[e-mail]>, [e-mail] (Leo Hendry) writes:
|> I have heard programmers say more than once that it is just too much hassle
|> using some of the Amiga's hardware (and naturally, too slow when used through
|> the OS, which is the only compatable way), and they much prefered a machine
|> with a processor fast enough to handle things itself (ie STs).
|>   I was looking through an Amiga manual some time back now, and I from what I
|> remember, all the hardware can do is draw horizontal lines.  Now while this
|> is exactly what is needed by most polygon drawing routines, unless the polygon
|> is very large the setting up of the coprocessor takes longer than embeded
|> 68000 code would to draw the horizontal lines.  If you access the hardware
|> through the OS (Which is now the only way because CBM no longer document the
|> new chipsets at a hardware level), then you would have to have a gigantic
|> polygon for it to be faster using some coprocessor or other.

Well in use this doesn't actaully seem to be the case. I have a program, written
in compiled BASIC on my 1200, which uses the AmigaDOS Graphics.library to bulid
up shapes from filled triangles using the blitter, and it is incredibly fast. It
also uses a negligible amount of processor time and any other programs I'm
running (including 25fps animations) still run at full speed. The point is that
if you use the Co-processor to perform your effects, the processor is still free
to perform other tasks.

|>   Sprites are a different matter though - from what I remember they are
|> overlaid on the screen memory by the video circitry with out taking any
|> processor time or changing the screen memory.  As has been said this makes the
|> Amiga far, far better than the ST for those moronic Super Mario-type games
|> that 5 year olds seem to like to much.

Actually, the hardware sprites tend never to be used by games, which rely on the
blitter to produce software sprites. They are, however, used quite a lot under
AmigaDOS. The mouse pointer is a sprite, and SoundTracker and MED type programs
tend to use them as equalizer bars. They are quite good in these circumstances
since, as you correctly point out, they are overlaid on top of the screen, and
can have their own resoloution and palette.

Chris Brown