python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Lib/turtledemo/penrose.py

@@ -0,0 +1,178 @@
+#!/usr/bin/env python3
+"""       xturtle-example-suite:
+
+          xtx_kites_and_darts.py
+
+Constructs two aperiodic penrose-tilings,
+consisting of kites and darts, by the method
+of inflation in six steps.
+
+Starting points are the patterns "sun"
+consisting of five kites and "star"
+consisting of five darts.
+
+For more information see:
+ http://en.wikipedia.org/wiki/Penrose_tiling
+ -------------------------------------------
+"""
+from turtle import *
+from math import cos, pi
+from time import clock, sleep
+
+f = (5**0.5-1)/2.0   # (sqrt(5)-1)/2 -- golden ratio
+d = 2 * cos(3*pi/10)
+
+def kite(l):
+    fl = f * l
+    lt(36)
+    fd(l)
+    rt(108)
+    fd(fl)
+    rt(36)
+    fd(fl)
+    rt(108)
+    fd(l)
+    rt(144)
+
+def dart(l):
+    fl = f * l
+    lt(36)
+    fd(l)
+    rt(144)
+    fd(fl)
+    lt(36)
+    fd(fl)
+    rt(144)
+    fd(l)
+    rt(144)
+
+def inflatekite(l, n):
+    if n == 0:
+        px, py = pos()
+        h, x, y = int(heading()), round(px,3), round(py,3)
+        tiledict[(h,x,y)] = True
+        return
+    fl = f * l
+    lt(36)
+    inflatedart(fl, n-1)
+    fd(l)
+    rt(144)
+    inflatekite(fl, n-1)
+    lt(18)
+    fd(l*d)
+    rt(162)
+    inflatekite(fl, n-1)
+    lt(36)
+    fd(l)
+    rt(180)
+    inflatedart(fl, n-1)
+    lt(36)
+
+def inflatedart(l, n):
+    if n == 0:
+        px, py = pos()
+        h, x, y = int(heading()), round(px,3), round(py,3)
+        tiledict[(h,x,y)] = False
+        return
+    fl = f * l
+    inflatekite(fl, n-1)
+    lt(36)
+    fd(l)
+    rt(180)
+    inflatedart(fl, n-1)
+    lt(54)
+    fd(l*d)
+    rt(126)
+    inflatedart(fl, n-1)
+    fd(l)
+    rt(144)
+
+def draw(l, n, th=2):
+    clear()
+    l = l * f**n
+    shapesize(l/100.0, l/100.0, th)
+    for k in tiledict:
+        h, x, y = k
+        setpos(x, y)
+        setheading(h)
+        if tiledict[k]:
+            shape("kite")
+            color("black", (0, 0.75, 0))
+        else:
+            shape("dart")
+            color("black", (0.75, 0, 0))
+        stamp()
+
+def sun(l, n):
+    for i in range(5):
+        inflatekite(l, n)
+        lt(72)
+
+def star(l,n):
+    for i in range(5):
+        inflatedart(l, n)
+        lt(72)
+
+def makeshapes():
+    tracer(0)
+    begin_poly()
+    kite(100)
+    end_poly()
+    register_shape("kite", get_poly())
+    begin_poly()
+    dart(100)
+    end_poly()
+    register_shape("dart", get_poly())
+    tracer(1)
+
+def start():
+    reset()
+    ht()
+    pu()
+    makeshapes()
+    resizemode("user")
+
+def test(l=200, n=4, fun=sun, startpos=(0,0), th=2):
+    global tiledict
+    goto(startpos)
+    setheading(0)
+    tiledict = {}
+    a = clock()
+    tracer(0)
+    fun(l, n)
+    b = clock()
+    draw(l, n, th)
+    tracer(1)
+    c = clock()
+    nk = len([x for x in tiledict if tiledict[x]])
+    nd = len([x for x in tiledict if not tiledict[x]])
+    print("%d kites and %d darts = %d pieces." % (nk, nd, nk+nd))
+
+def demo(fun=sun):
+    start()
+    for i in range(8):
+        a = clock()
+        test(300, i, fun)
+        b = clock()
+        t = b - a
+        if t < 2:
+            sleep(2 - t)
+
+def main():
+    #title("Penrose-tiling with kites and darts.")
+    mode("logo")
+    bgcolor(0.3, 0.3, 0)
+    demo(sun)
+    sleep(2)
+    demo(star)
+    pencolor("black")
+    goto(0,-200)
+    pencolor(0.7,0.7,1)
+    write("Please wait...",
+          align="center", font=('Arial Black', 36, 'bold'))
+    test(600, 8, startpos=(70, 117))
+    return "Done"
+
+if __name__ == "__main__":
+    msg = main()
+    mainloop()