Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!wuarchive!mit-eddie!uw-beaver!zephyr.ens.tek.com!tekig5!wayneck
From: wayneck@tekig5.PEN.TEK.COM (Wayne C Knapp)
Newsgroups: comp.sys.amiga
Subject: Re: Frame Buffers
Message-ID: <5715@tekig5.PEN.TEK.COM>
Date: 28 Feb 90 16:33:27 GMT
References: <1689@crash.cts.com>
Organization: Tektronix Inc., Beaverton, Or.
Lines: 54

In article <1689@crash.cts.com>, bobl@pro-graphics.cts.com (Bob Lindabury) writes:
> Seems the boys at Byte by Byte could care less about us Amiga users because
> they are going after the Mac carrot (or is that Apple?).  At any rate, it
> seems that not much forethought was put into the Sculpt product and they opted
> to optimize the redering routines for the Amiga's display modes and didn't
> even consider 24 bit rendering to any large degree.  Seems the software will
> produce these bands so that another routine can dither between them to get
> those nice HAM images.  Too bad that the bands are not skipped when rendering
> in 24 bit mode.  So, an otherwise perfectly good product is "rendered" next to
> useless for 24 bit images.  Yeah, doesn't everyone want to drop $500 for a 3d
> ray tracer that doesn't do 24 bit well?  How about we all drop our bucks on
> the product so that Byte by Byte can do more Mac developement?  These ideas
> dosn't sound good to you?  Hmm...

The problem isn't rendering to 24 bits.  It sounds like that works just fine.
Once you have 24 bits per pixel rendered and displayed it isn't possible to 
dither anymore.  What data can be used to control the dithering?  One could
take the 24 bit image and dither it to say an 18 bit images (6 bits per red,
green, blue).  This would reduce the number of colors in the image and reduce
the resolution to a lesser degree.  It would be similar to running the image
though a low-pass filter.  Anyway the picture would become kind of HAMish, that
is it would appear softer.  If you want to dither to 24 bits, you have render
something like 30 bits per pixel or 36 bits per pixel would be even better.
Then you have some data to dither on. 

> I'm still waiting for a "good" 3D program with an interface like Caligary,
> Editing easy like Sculpt and rendering/mapping capabilities like Turbo Silver.
> If all the best of each of these programs were incorporated into a new 3d
> program that also supported the Renderman Spec, I would (as others would) jump
> on it in a second even if it did cost in the $1000-$2000 range.

I think you realize what Renderman is all about.  Anyway if you what to use it
be prepared to pay a lot.  The main feature the Pixar uses is called 'shaders'.
Only there is a problem --- 'shaders' are not a part of the Renderman Spec..
This means if you want those Pixar quality pictures you better buy Pixar's
Renderman Render.  Also shaders are pieces of code so if you aren't hot at
physics and programming you end up paying a lot to get them written.  (Pixar
has to make money after all.)  However, the end product can be amazing.  The
sharders can turn a run of the mill image into a near photo-realistic image.
What will this cost?  Well the Pixar Renderman render sells for $4650, plus
you need a Mac II or PC with a transputer board if you want images in less 
than an hour.  You are looking a $10,000 to $15,000.  Still hot on Renderman?

Well if you want a true Amiga solution and $1000 doesn't scare you off, give
Martin Hash a call.  Ask him about Animation:Jorneyman. (206) 573-9427. 
  
> You mention nice dithering in Turbo for 24 bit images.  I'm not sure what you
> mean by that but with a 24 bit image (over 16 million colors available) you do
> not need to do any dithering.

This is simply not true.  It is very possible for 24 bit images to have 
banding.  Isn`t that what you were complaining about at the biginning of 
this article.
                                               Wayne Knapp