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graphtal.txt
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1993-12-08
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Short: Trees,Plants...from grammars(rayshade)
DESCRIPTION
graphtal is a tool for manipulating spT0L-systems (context
free, table oriented L-systems with stochastic productions).
graphtal reads a file containing an L-system description and
starts the interpretation. In addition, graphtal is able to
interpret the result graphically, producing different kinds
of output.
The main reference for the program is the book The Virtual
Laboratory: The Algorithmic Beauty of Plants by P. Prusink-
iewicz and A. Lindenmayer. The language used in graphtal is
different from the one in the book and will be described
completely in this document.
DEVICE DRIVERS
EXAMPLE DEVICE
The example driver produces a ASCII dump of the primitives
generated. It shows the easiest way to implement a driver.
BBOX DEVICE
The bbox driver computes the bounding box and gives a hint
for the viewing parameters of the objects defined by the L-
system description. This is useful for the flat device,
which does no automatic view computations.
LINE DEVICE (X11,AMIGA)
This driver generates a simple line drawing of the object
defined by the L-system. Line width, color, textures,
spheres, macros and library object are not supported by this
driver. Viewing parameters are automatically set, when none
are provided by the user.
WIRE DEVICE (X11,AMIGA)
The wire device driver draws a more realistic image of the
object than line device. Not supported are colors, textures
and library objects. Viewing parameters are also set
automatically, when none are provided.
FLAT DEVICE
The flat device works with a z-buffer algorithm, which is
able to shade convex and concave polygons. Shading calcula-
tions are done with regard to the light source located at
the eyepoint. The driver does not depend on the number of
polygons, therefore even very large scenes can be visual-
ized. As a drawback of this feature, the viewing parameters
have to be provided by the user (use BBOX DEVICE to calcu-
late them). Textures and library objects are not supported
by this driver. The output of the rendering process is an
image in ppm format (portable pixmap).
RAYSHADE DEVICE
The rayshade device is the most complete of all the drivers.
It generates output for the raytracer rayshade. The driver
produces at least two output files:
graphtal -d rayshade anExample.lsys
generates the files default.ray and default.ray.def
graphtal -d rayshade -O anExample.ray
generates the files anExample.ray and anExample.ray.def.
The file name.ray contains the options for the rendering
process and in the name.ray.def file the geometric primi-
tives are stored. For each macro definition, the rayshade
driver produces it's own file with the name
macrName.ray.def. If library objects are used, a file with
the name libraryName.ray.lib must be provided by the user
for each object.
AUTHOR
Christoph Streit (streit@iam.unibe.ch)
AMIGA PORT
Lucas Ammon (lammon@iamexwi.unibe.ch)
COPYRIGHT NOTICE
Copyright (C) 1992 Christoph Streit
All rights reserved.
This software may be freely copied, modified, and redistri-
buted provided that this copyright notice is preserved on
all copies.
You may not distribute this software, in whole or in part,
as part of any commercial product without the express con-
sent of the authors.
There is no warranty or other guarantee of fitness of this
software for any purpose. It is provided solely "as is".
Last change: October 27, 1992 16