home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Collection of Tools & Utilities
/
Collection of Tools and Utilities.iso
/
graphic
/
rtnews.zip
/
RTNEWS7
< prev
next >
Wrap
Text File
|
1992-09-13
|
24KB
|
622 lines
_ __ ______ _ __
' ) ) / ' ) )
/--' __. __ , --/ __ __. _. o ____ _, / / _ , , , _
/ \_(_/|_/ (_/_ (_/ / (_(_/|_(__<_/ / <_(_)_ / (_</_(_(_/_/_)_
/ /|
' |/
"Light Makes Right"
May 12, 1989
Volume 2, Number 3
Compiled by Eric Haines, 3D/Eye Inc, 2359 Triphammer Rd, Ithaca, NY 14850
607-257-1381, hpfcla!hpfcrs!eye!erich@hplabs.hp.com
All contents are US copyright (c) 1989 by the individual authors
Contents:
Introduction
New People (Carl Bass, Paul Wanuga)
QRT Ray Tracer (and five other Amiga Ray Tracers) (Steve Koren)
New Version of MTV Ray Tracer (Mark VandeWettering)
Minimal Sphere Containing Three Points (Earl Culham)
Noise and Turbulence Function Code, Pascal and C (Jon Buller,
William Dirks)
-----------------------------------------------------------------------------
Introduction
Well, we're now at the point where there are six ray tracers for the Amiga.
Interestingly, none of them have implicit efficiency schemes (i.e. where the
user does not have to intervene and create the efficiency structure himself).
Admittedly, efficiency schemes are more code, but I've found that I was getting
a factor of three speed up for a simple scene (a ten ball sphereflake) by using
an efficiency scheme vs. not using one. When your computer is the speed of an
Amiga, efficiency schemes become vital.
Next time I'll include "Tracing Tricks", an article I "edited" for the latest
(and last) "Introduction to Ray Tracing" course notes. The article is a "best
of the RT News" compendium of efficiency tricks. By the way, the course notes
should be quite a bargain: they'll consist of the book of our notes by Academic
Press, plus some new tidbits and reprints of "classic" articles.
I would like to put the "Ray Tracing News" back issues somewhere that people
can FTP them. Personally I don't have a computer that has an FTP site, so if
there are any volunteers that would like to store the back issues, please
contact me. The entire archive is about 448K at this point (not including this
issue), broken into 5 parts. Can you volunteer?
-----------------------------------------------------------------------------
# Carl Bass - hybrid shading models and quick(er) hidden surface methods
# Ithaca Software
# 902 West Seneca Street
# Ithaca, NY 14850
# 607-273-3690
alias carl_bass carl@mssun1.msi.cornell.edu
Carl is the co-founder of Ithaca Software Inc (once upon a time called "Flying
Moose Inc"), which sells the HOOPS package for all kinds of computers. This is
an object-oriented system which I don't know much about beyond that their
debugger is called WHOOPS.
--------
#
# Paul Wanuga
# Cornell Program of Computer Graphics
# 120 Rand Hall
# Ithaca, NY 14853
# (607)-255-4880
alias paul_wanuga phw@love.tn.cornell.edu
Erich:
Could you please include me in your list of wiz-bango ray tracers? It
appears Don has me slated for research in ray-tracing complex, realistic,
non-procedural environments.
-----------------------------------------------------------------------------
QRT Ray Tracer (and five other Amiga Ray Tracers), Steve Koren
This package appeared on comp.graphics a few months back. I believe
the latest version of the package is available from Mark VandeWettering's FTP
site (see next article). Write to Steve for more info:
hpfela!koren@hplabs.hp.com
The software is written in C and worked just fine on my system. Below is an
excerpt of the UserMan.doc file of the QRT system (which Steve extensively
documented).
QRT is a ray tracing image rendering system that runs under a
variety of operating systems. It has a free format input
language with extensive error detection and reporting
capabilities.
QRT was developed on the Amiga personal computer, so it will
be compared to other Amiga ray tracers. There are, to my
knowledge, five other Amiga ray tracers, each with its own
strengths and weaknesses. I will describe each system
briefly, and compare it to QRT. All the Amiga ray tracers can
operate in HAM (4096 color) mode.
RT: RT was the first ray tracer written for the Amiga, by
Eric Graham. It will model a universe made of only
spheres, a sky, and a checkered or solid ground. It
is relatively fast, but not generally useful for
realistic modeling because of the sphere limitation.
The input language is cryptic, although some error
checking is done. The system will only generate low
resolution images.
SILVER: I have never seen SILVER, so I cannot say much about
this system.
SCULPT-4D: This package incorporates an interactive editor
for creating objects, and is capable of quickly
generating a preliminary image of the scene by using
hidden surface techniques. However, every primitive is
made of polygons, and some primitives such as spheres
require hundreds of polygons for a smooth texture, so
the ray tracing is very slow. Also, the package takes
a large amount of memory to run, and is prone to system
crashes. Its chief feature is the ability to create
arbitrary shaped objects using a series of triangles.
Mirrored, dull, or shiny objects are supported.
CLIGHT: This ray tracer also has an interactive editor, but
produces very poor quality images. It is not capable
of any patterning or reflection characteristics.
DBW: This is possibly the most complete ray tracer for the
Amiga. It will support objects with arbitrary degrees
of reflection and gloss, depth of field effects, some
texturing, wavy surfaces, fractals, transparent
surfaces, diffuse propagation of light from object to
object, and 5 primitive types (sphere, triangle,
parallelogram, fractal, and ring). The input language,
however, is so cryptic as to be nearly
incomprehensible, and if there is any error in the
input file, it will crash the system. It is also
painfully slow; some images take 16 to 24 hours to
complete.
QRT is meant to be a compromise between the fast, simple ray
tracers and the slow powerful systems. It compares favorably
in speed to RT, and in power to Sculpt-3d or DBW. It has a
very friendly input language with extensive error checking.
Here are some features of QRT:
o Multiple primitive types, including user defined
quadratic surfaces
o Arbitrary levels of diffuse reflection, spectral
reflection, transmission, ambient lighting, and gloss
o User defined pattern information for objects
o Bounding boxes for groups of objects
o Shadows
o Multiple light sources with different characteristics
o Arbitrary Phong spectral reflection coefficients
o Color dithering to increase the apparent number of
colors
o Easy to use, free format input language with error
checking. Parameters are by keyword and may appear in
any order.
o Supports medium resolution (128k dots/screen)
-----------------------------------------------------------------------------
New Version of MTV Ray Tracer, Mark VandeWettering
Mark VandeWettering's nice little ray tracer (polygons, spheres, cones and
cylinders, Kay/Kajiya efficiency scheme, yacc/lex parser for NFF format,
otherwise written in C) was released on USENET in three parts on March 27.
Others have interesting features, but the selection of primitives and the speed
of the code of the MTV ray tracer is a big plus. It's currently my favorite
public domain ray tracer (the amazing BRL package I consider private).
The package is available at the usual comp.sources.unix archive