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############################################################################
#
# File: lindterp.icn
#
# Subject: Procedure to interpret and draw L-System strings
#
# Author: Ralph E. Griswold
#
# Date: May 2, 2001
#
############################################################################
#
# This file is in the public domain.
#
############################################################################
#
# This procedure interpreters strings of characters produced by
# L-Systems and draws them using turtle graphics.
#
############################################################################
#
# Links: lindrec, lindgen, turtle
#
############################################################################
link lindrec
link lindgen
link turtle
global size
# length is the length of line segments and delta is the amount of
# direction change.
procedure lindterp(x, y, lsys, gener, length, color, fnc)
local rewrite, delta, axiom, symbols, c
/size := 500
/x := size / 2
/y := size / 2
rewrite := lsys.rewrite
axiom := lsys.axiom
delta := lsys.delta
/gener := lsys.gener
/length := lsys.length
# The table symbols contains definitions for other symbols as
# string of other characters. It remains to be seen how this
# will be represented. Note also there is a potential for
# circularity and unbounded recursion.
symbols := table() # table of defined symbols
TReset()
TGoto(x, y)
every c := lindgen(!axiom, rewrite, gener) do
case c of {
"F": TDraw(length) # draw forward
"f": TSkip(length) # skip forward
"+": TRight(delta) # turn right
"-": TLeft(delta) # turn left
"[": TSave() # save state
"]": TRestore() # restore state
# interpret defined symbol
default: lindterp(\symbols[c], length, delta)
} # ignore other characters
WFlush()
return
end
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