From: timm@void.ncsa.uiuc.edu (Tim McClarren)
Subject: Re: NeXT's, Amiga's, PC's, MAC'S, (was Re: Question #2 "Are Macintosh Users Really Happy?")
Organization: University of Illinois at Urbana
Date: Mon, 31 Aug 1992 01:02:55 GMT

mmelling@Trirex.com(Michael Mellinger) writes:

>In article <dillon.0m05@overload.Berkeley.CA.US>  
>dillon@overload.Berkeley.CA.US (Matthew Dillon) writes:
> >dillon@overload.Berkeley.CA.US (Matthew Dillon) writes:
>>     blitter isn't the fastest in the world, it runs asynchronous to the
>>     rendering operations requested by any given process and quite a bit  
>of
>>     overhead is absorbed, which is why rendering operations on a lowly
>>     68000 Amiga are quite fast and can be said to blaze on faster
>>     processors.

>What does asynhronous have to do with anything?  If you figure that that  
>Amiga blitter is equivalent to a 68030 in processing speed (CPUBLT is  
>faster on a 68030 for many blits) then you have 2x68030 is processing  
>speed on an A3000.  A 68040 is 3x68030 in integer performance.  In other  
>words, the 25MHz 68040 NeXT is capable of doing more work in 1 second than  
>the Amiga.  If you figure that a 80586 clone running NeXTstep or 88110  
>RISC NeXT will be at least 3 times faster than the current NeXTstation,  
>then it looks like animation will be much nicer on the next generation of  
>NeXT computers.

Hmm...I haven't really been following this thread very closely, but 
I noticed this post.  Asynchronous may have a lot to do with animation.
Anyways, equating the Amiga blitter with a 68030 is dangerous at best.
And the comment the the 040 is 3 times faster than the 030 in integer
performance may have little or nothing to do with animation speed.
The first poster has made a very valid point...hardware blitters (or
any form of hardware rendering) can make a definite improvement
in graphics performance.

>I believe that if programmers could sync to the vertical retrace on the  
>monitor then much better animation could be done on the current machines.   
>Drawing to an off-screen window and flushing the dirty rects to the screen  
>is time consuming.  You also have to consider that the NeXT has a network  
>transparent window system.  You aren't making a simple function call like  
>you are on the Amiga (some programmers on the Amiga don't even make the  
>function call).

This may make animation "prettier", but it has little to do with animation
performance (the sync'ing bit).  Anyways, the maximum appreciable FPS 
you'd want would be whatever said sync. rate is.  A 486 PC (33 Mhz) can
do about 200 FPS in the 320x200 x-mode of the VGA card (I know this is
true because someone here has done it with a their own 2D graphics library
specially tailored for this mode).  It's ridiculous, because for every 
frame you see there are 3 that you don't.  But there are other issues as
well, for instance on the Macintosh, NuBus will be a bottleneck soon
(and some would say that it is already a bottleneck).  But, all things
considered, if you can get 20-30 FPS in a decent sized full color window
using a buffer and flushing dirty rects, the convenience pays for itself
and any speed increase at the cost of using a less simple drawing environment
isn't a good trade-off in my book.
-- 
Tim McClarren     | "...a bajillion brilliant Jobsian lithium licks."
timm@ncsa.uiuc.edu|
(217)244-0015     |
Newsgroups: comp.sys.next.advocacy