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Diffstat (limited to 'ipl/gprogs/sier.icn')
| -rw-r--r-- | ipl/gprogs/sier.icn | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/ipl/gprogs/sier.icn b/ipl/gprogs/sier.icn new file mode 100644 index 0000000..a0b48cf --- /dev/null +++ b/ipl/gprogs/sier.icn @@ -0,0 +1,218 @@ +############################################################################ +# +# File: sier.icn +# +# Subject: Program for generalized Sierpinski's triangle +# +# Author: Gregg M. Townsend +# +# Date: June 10, 2004 +# +############################################################################ +# +# This file is in the public domain. +# +############################################################################ +# +# Originally inspired by the Nova television show on chaos. +# Colorization suggested by Kenneth Walker. +# +############################################################################ +# +# This program constructs Sierpinski's triangle using an iterative +# method. An initial point is chosen (by clicking the mouse inside the +# triangle) and marked. Then, the program repeatedly moves half way to +# a randomly chosen vertex and plots a point in the color corresponding +# to the vertex. +# +# The polygon need not be a triangle. The number of sides may be given +# as a command line argument, or a digit 3 through 9 or 0 through 2 may be +# pressed to establish a new polygon of 3 to 12 sides. +# +# The S, G, E, and Q keys function identically to the Stop, Go, Erase, +# Quit pushbuttons. +# +############################################################################ +# +# Requires: Version 9 graphics +# +############################################################################ +# +# Links: button, evmux, random, graphics +# +############################################################################ + +link button +link evmux +link random +link graphics + +$define BevelWidth 2 +$define WindowMargin 10 + +global win, bwin, vwin, vcolors +global m, w, h +global nsides, xpos, ypos, outline +global running, xcur, ycur + +procedure main(args) + local i, vcolors + + win := Window("size=400,400", "font=Helvetica,bold,14", "bg=pale gray", args) + nsides := integer(args[1]) | 3 + if nsides < 3 then stop("sierpinski: need at least 3 sides!") + + m := WindowMargin + h := WAttrib("height") - 2 * m # usable height + w := WAttrib("width") - 2 * m # usable width + + # make a window (g.c.) for drawing in background color + bwin := Clone(win) + Fg(bwin, Bg(win)) + + # make a color for each vertex + vcolors := [ + "deep green", + "dark red", + "dark blue", + "deep red-magenta", + "dark cyanish blue", + "dark red-orange", + "deep purple", + "deep cyan", + "deep brown", + "deep orangish red", + "deep purple", + "dark cyanish blue" + ] + vwin := [] + if WAttrib(win, "depth") > 2 then + every put(vwin, Clone(win, "fg=" || !vcolors)) + else + put(vwin, win) + + # configure and draw the polygon + configure() + erase() + + # set up buttons and character handlers + button(win, "Go", setfill, 0, m, m, 50, 20) + button(win, "Stop", setfill, -1, m, m + 30, 50, 20) + button(win, "Erase", argless, erase, m + w - 50, m, 50, 20) + button(win, "Quit", argless, exit, m + w - 50, m + 30, 50, 20) + sensor(win, 'Gg', setfill, 0) + sensor(win, 'Ss', setfill, -1) + sensor(win, 'Ee', argless, erase) + quitsensor(win) # enable Q-for-quit etc. + sensor(win, '3456789012', setsides) + + # set up sensor for drawing the curve + sensor(win, &lrelease, setfill, 1, m, m, w, h) + + # process events + randomize() + i := 1 + repeat { + while *Pending(win) > 0 | running < 0 do + evhandle(win) + every 1 to 100 do { + DrawPoint(vwin [i | 1], xcur, ycur) + i := ?nsides + xcur := (xcur + xpos[i]) / 2 + ycur := (ycur + ypos[i]) / 2 + } + } +end + + + +# configure() -- set vertex points + +procedure configure() + local a, da, i + local xmin, xmax, xscale, ymin, ymax, yscale + + # ensure we have enough windows for the vertices + while *vwin < nsides do + vwin |||:= vwin + + # get coordinates for vertices as points on a radius-1 circle + da := 2 * &pi / nsides + a := 1.5 * &pi - da / 2 + if nsides = 4 then + a +:= &pi / 12 + xpos := list(nsides) + ypos := list(nsides) + every i := 1 to nsides do { + xpos[i] := cos(a) + ypos[i] := sin(a) + a -:= da + } + + # now scale to available window size + # also make coord list for drawing outline + xmin := xmax := ymin := ymax := 0.0 + every xmin >:= !xpos + every xmax <:= !xpos + every ymin >:= !ypos + every ymax <:= !ypos + xscale := w / (xmax - xmin) + yscale := h / (ymax - ymin) + outline := [win] + every i := 1 to nsides do { + put(outline, m + xscale * (1.01 * xpos[i] - xmin)) + put(outline, m + h - yscale * (1.01 * ypos[i] - ymin)) + xpos[i] := m + xscale * (xpos[i] - xmin) + ypos[i] := m + h - yscale * (ypos[i] - ymin) + } + put(outline, outline[2]) + put(outline, outline[3]) +end + + + +# erase(gc) -- erase the polygon and draw its outline + +procedure erase(gc) + outline[1] := bwin + FillPolygon ! outline + outline[1] := \gc | win + DrawLine ! outline + running := -1 + xcur := m + w / 2 + ycur := m + h / 2 + return +end + + + +# setfill(win, n, x, y) -- start/stop filling points according to n +# +# n<0 stop +# n=0 start, from current point +# n>0 start, from (x,y) + +procedure setfill(win, n, x, y) + if n > 0 then { + xcur := x + ycur := y + } + if n >= 0 then { + outline[1] := bwin + DrawLine ! outline # erase outline + } + running := n + return +end + + + +# setsides(win, dummy, x, y, event) - reset the number of sides + +procedure setsides(win, dummy, x, y, event) + nsides := integer(event) + if nsides < 3 then nsides +:= 10 + erase(bwin) + configure() + erase() +end |