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############################################################################
#
# File: spiral.icn
#
# Subject: Program to draw polygonal spirals
#
# Author: Stephen B. Wampler
#
# Date: June 17, 1994
#
############################################################################
#
# This file is in the public domain.
#
############################################################################
#
# Version: 1.0
#
############################################################################
#
#
# Comments: This program displays polyline based spiral
#
# See the procedure 'helpmsg' for command line options
# (or run as 'spiral -help')
#
# Waits for a window event before closing window
#
############################################################################
#
# Links: glib, wopen
#
############################################################################
#
# Requires: Version 9 graphics and co-expressions (for glib.icn)
#
############################################################################
link glib
link wopen
global win, mono, h, w
global Window, XMAX, YMAX
procedure main (args)
local dist, angle, incr, n, nextarg, arg, t
XMAX := YMAX := 700 # physical screen size
w := h := 1.0
dist := 0.02
angle := 144
incr := 0.01
n := 100
nextarg := create !args
while arg := @nextarg do {
if arg == ("-help"|"-h") then stop(helpmsg())
if match(arg, "-distance") then dist := numeric(@nextarg)
else if match(arg, "-angle") then angle := numeric(@nextarg)
else if match(arg, "-increment") then incr := numeric(@nextarg)
else if arg == "-n" then n := integer(@nextarg)
}
win := WOpen("label=Poly Spiral", "width="||XMAX, "height="||YMAX)
mono := WAttrib (win, "depth") == "1"
Window := set_window(win, point(0,0), point(w,h),
viewport(point(0,0), point(XMAX, YMAX), win))
EraseArea(win)
Fg(win, "black")
t := turtle(Window, point(w/2, h/2), 0)
polyspiral(t, dist, angle, incr, n)
Event(win)
close(win)
end
procedure polyspiral(t, dist, angle, incr, n)
local i
every i := 1 to n do {
Line_Forward(t, dist)
Right(t, angle)
dist +:= incr
}
end
procedure helpmsg()
write("Usage: Spiral [-d dist] [-a angle] [-i increment] [-n nlines]")
write(" where")
write(" -d N -- initial line length {default: 0.02")
write(" -a N -- angle of change (degrees) {144}")
write(" -i N -- incremental change to line {0.01}")
write(" -n N -- number of lines to draw {100}")
return
end
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