Path: utzoo!utgpu!attcan!uunet!pyrdc!netsys!lamc!well!shf
From: shf@well.UUCP (Stuart H. Ferguson)
Newsgroups: comp.sys.amiga
Subject: Re:  Sculpt-4D Upgrade
Summary: Not all scanline renderers are "brain-damaged."
Message-ID: <7366@well.UUCP>
Date: 13 Oct 88 20:44:33 GMT
References: <4779@louie.udel.EDU>
Reply-To: shf@well.UUCP (Stuart H. Ferguson)
Organization: The Blue Planet
Lines: 48


| >I feel that ray tracing is too exotic a process
| >to be valuable to production on a small machine. Scanline renderers are MUCH
| >faster and produce virtually the same result.
|  [ ... ]  Nonetheless, I agree that it has been under-utilized on the
| Amiga.  And when it has been utilitized, it has been brain-damaged.  Why
| can't these people do smoothing in scanline mode?  It's a lot easier to
| implement than in ray-tracing mode...

The writer obviously doesn't shop around.  VideoScape 3D version 2.0,
which has been available for five months, does scanline-like rendering
(Z-buffering) with smoothing.  It uses the Phong shading model and Phong
interpolation to render diffuse and specular smoothly shaded objects in
HAM mode.  The results are quite good and blindingly fast compared to
raytracing.  Most VS 3D 2.0 ads in magazines have a picture of the Mask,
a smoothly shaded face, and its "reflection" in a checkerboard floor,
which was rendered in overscan HAM in about 4 minutes on a stock Amiga
(no '020 or '881). 

Forms in Flight II also does scanline rendering with smoothing although 
it does not support HAM mode.

| > I think they should also offer some kind ascii format of their objects. This
| >way someone could write a myriad of programs to manipulate te objects which 
| >could supplement the main programs.
| What's that?  You don't read IFF?  [ ... ]

I beg to differ.  Sculpt-3D's file format is not IFF, regardless of the
fact that it's composed of FORMs and chunks and things.  It is not an
"Interchange File Format" because it's not documented and therefore
cannot be used for data _interchange_.  For the same reason, Sculpt's
"movie" files are not ANIMs. 

For an ASCII format, VideoScape 3D's ASCII geometry format is well
documented and can be used to create or manipulate objects.  With the
"Interchange" program, you can convert these files into Sculpt format. 
With some exceptions, like the limitations on the colors in VideoScape
format or the limitations on polygons in Sculpt format, the two formats
are reasonably compatable. 

|                             --Ken Van Camp 

Sorry for the possible commercial nature of this posting.  Since I have
some affiliation with VideoScape 3D, I naturally wish to see misinformation
corrected. 
-- 
		Stuart Ferguson		(shf@well.UUCP)
		Action by HAVOC		(shf@wso.Stanford.EDU)