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Diffstat (limited to 'ipl/gpacks/weaving/lindpath.icn')
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1 files changed, 206 insertions, 0 deletions
diff --git a/ipl/gpacks/weaving/lindpath.icn b/ipl/gpacks/weaving/lindpath.icn new file mode 100644 index 0000000..d724479 --- /dev/null +++ b/ipl/gpacks/weaving/lindpath.icn @@ -0,0 +1,206 @@ +############################################################################ +# +# File: lindpath.icn +# +# Subject: Program to create paths for 0L-systems +# +# Author: Ralph E. Griswold +# +# Date: June 19, 1999 +# +############################################################################ +# +# This file is in the public domain. +# +############################################################################ +# +# This program reads in a 0L-system (Lindenmayer system) consisting of +# rewriting rules in which a string is rewritten with every character +# replaced simultaneously (conceptually) by a specified string of +# symbols. +# +# Rules have the form +# +# S->SSS... +# +# where S is a character. +# +# In addition to rules, there are keywords that describe the system and how +# to draw it. These include the "axiom" on which rewriting is started and +# optionally the angle in degrees between successive lines (default 90). +# Other keywords are ignored. +# +# Keywords are followed by a colon. +# +# An example 0L-system is: +# +# X->-FX++FY- +# Y->+FX--FY+ +# F-> +# -->- +# +->+ +# axiom:FX +# angle:45.0 +# xorg:100 +# yorg:100 +# +# Here, the initial string is "FX" and angular increment is 45 degrees. +# Note that "-" is a legal character in a 0L-system -- context determines +# whether it's 0L character or part of the "->" that stands for "is +# replaced by". +# +# If no rule is provided for a character, the character is not changed +# by rewriting. Thus, the example above can be expressed more concisely +# as +# +# X->-FX++FY- +# Y->+FX--FY+ +# F-> +# axiom:FX +# angle:45.0 +# +# The recognized keywords are: +# +# axiom axiom for generation +# angle angular increment for turns +# length segment length +# xorg x origin +# yorg y origin +# comment comment; ignored +# +# Distances increase from left to right in the x direction and from top +# to bottom in the y direction. +# +# As pure-production systems, the characters are symbolic and have no +# meaning. When interpreted for drawing, the characters have the +# following meaning: +# +# F move forward by length +# f move backward by length +# + turn right by angle +# - turn left by angle +# [ save current state +# ] restore current state +# +# The file containing the 0L-systems is read from standard input. +# +# The command-line options are: +# +# -g i number of generations, default 3 +# -l i length of line segments, default 5 +# -a i angular increment in degrees (overrides angle given in +# the grammar) +# -w i window width +# -h i window height +# -x i initial x position, default mid-window +# -y i initial y position, default mid-window +# -W write out string instead of drawing +# -s take snapshot of image +# -d i delay in milliseconds between symbol interpretations; +# default 0 +# +# References: +# +# Formal Languages, Arto Salomaa, Academic Press, 1973. pp. 234-252. +# +# The Algorithmic Beauty of Plants, Przemyslaw Prusinkiewicz and +# Aristid Lindenmayer, Springer Verlag, 1990. +# +# Lindenmayer Systems, Fractals, and Plants, Przemyslaw Prusinkiewicz and +# James Hanan, Springer Verlag, 1989. +# +############################################################################ +# +# See linden.dat for an example of input data. +# +############################################################################ +# +# Requires: graphics if drawing +# +############################################################################ +# +# Links: linddraw, options, tpath, wopen +# +############################################################################ + +link linddraw +link options +link tpath +link wopen + +procedure main(args) + local line, gener, axiom, angle, opts, i, s, c, symbol, rewrite + local allchars, rhs, value, spec, x, y, length, w, h, delay + + rewrite := table() + allchars := '' # cset of all rhs characters + + opts := options(args,"g+l+a+w+h+x+y+Wsd+") + + while line := read() do + line ? { + if symbol := move(1) & ="->" then { + rhs := tab(0) + rewrite[symbol] := rhs + allchars ++:= rhs # keep track of all characters + } + else if spec := tab(upto(':')) then { + move(1) + value := tab(0) + case spec of { + "axiom": { + axiom := value + allchars ++:= rhs # axiom might have strays + } + "angle": angle := value + "xorg": x := value + "yorg": y := value + "comment": &null # ignore comments + "length": length := value + "gener": gener := value + default: write(&errout, "unknown keyword: ", spec) + } # ignore others + } + else write(&errout, "malformed input: ", tab(0)) + } + +# At this point, we have the table to map characters, but it may lack +# mappings for characters that "go into themselves" by default. For +# efficiency in rewriting, these mappings are added. + + every c := !allchars do + /rewrite[c] := c + + h := \opts["h"] | 400 + w := \opts["w"] | 400 + + angle := \opts["a"] # command-line overrides + length := \opts["l"] + gener := \opts["g"] + x := \opts["x"] + y := \opts["y"] + delay := \opts["d"] + + /angle := 90 # defaults + /length := 5 + /gener := 3 + /x := 0 + /y := 0 + /delay := 0 + + if /axiom then stop("*** no axiom") + + TPath(x, y, -90.0) + + WDelay := WFlush := 1 + + linddraw(x, y, axiom, rewrite, length, angle, gener, delay) + + WOpen("size=" || w || "," || h, "dx=" || (w / 2), + "dy=" || (h / 2)) | stop("*** cannot open window") + + DrawPath(T_path) + + Event() + +end |