README

	    RELEASE NOTES FOR LSYS - March 21, 1991

    INTRODUCTION

    Lsys is a program to generate complex models using string
production systems called L-Systems. The program was inspired by the
Springer-Verlag text _The Virtual Laboratory: The Algorithmic Beauty
of Plants_, by P. Prusinkiewicz and A. Lindenmayer, and maintains as
much compatibility with their input format as I could manage.

    Documentation for the program is found in lsys.l in [nt]roff form
(process with the -man macros), and in lsys.cat in lineprinter form.
The book will be needed to make use of the program, as many semantic
issues are not documented in the (rather terse) man page.

    PORTING

    The code has been compiled and tested using AT&T C++ 2.0 on
DECstation 3100s, Sun C++ 2.0 on Sun-4s, and G++ 1.39.0 beta on both
DECstations and Sun-4s. It should port easily to other Unix platforms
using one of these compilers. The AT&T compiler is preferred as G++
has some bugs and does not have an iostream library; a 1.2 compatible
stream library lacking in features is used instead.

    The choice of compilers and tools (yacc/lex vs. bison/flex) is
made by editing the Makefile (comment out only one of the sections
beginning '# Unix tools' and '# GNU tools'). To override the Makefile
definitions and use CC with Unix tools, use the shell script
'make.att'. To override the definitions and use g++ with GNU tools,
use 'make.gnu'. By default, the Makefile is set up for G++ running on
a Sun-4 under SunOS 4.1.

    Some versions of malloc() allow more efficient allocation of small
blocks by the call mallopt(M_MXFAST, maxblocksize). If M_MXFAST is
defined by the <malloc.h> header file, lsys will attempt to use it. It
may be necessary to link an additional library to obtain this version
of malloc; for example, on DECstations running Ultrix, the -lmalloc
library must be used. The make variable MEMLIB may be set to specify
this library by editing the Makefile. The 'make.att' and 'make.gnu'
frontends attempt to automatically detect if they're being run on an
Ultrix system and use this library.

    There is a serious bug in g++ 1.39.0 beta in which a member
operator delete(void *) is incorrectly passed a NULL pointer instead
of a pointer to the memory to free. This causes enormous memory losses
and will constrain which models may be run. A fix posted on the net
is:

diff cplus-decl.c.~1~	 cplus-decl.c
7956c7956
<   build_tree_list (NULL_TREE, integer_zero_node),
---
>   build_tree_list (NULL_TREE, current_class_decl),

    This fix has not been applied or tested locally, so I can't vouch
for its correctness. To test if this bug exists in your g++, create a
test program 'bug' by 'make.gnu bug' and run it; it should print a
message indicating if the operator delete() bug exists.

    NEW OUTPUT FORMATS

    Currently, PostScript, a 'generic' output format, and two ASCII
formats used locally may be generated. It should be straightforward to
add new output formats for ray-tracers and such by subclassing class
DBGenerator, an abstract output class. See README.OUTPUT,
DBGenerator.[ch], and GenericGenerator.[ch]. Please send any output
generators for widely-used formats (e.g. NFF) to me for inclusion in
the distribution.

    EXAMPLES

    Examples drawn from the text are provided in the subdirectory
'Examples' (see README.EXAMPLES), and may be examined to gain
familiarity with the input format. With few exceptions (see BUGS in
the man page), these produce images and databases very close to those
in the book.

    BUGS

    Please contact me via email with bug reports (accompanied by
L-systems causing them), interesting L-systems for inclusion in the
release, enhancements, and suggestions.

    Jon Leech (leech@cs.unc.edu)
    __@/