1 files changed, 86 insertions, 0 deletions
diff --git a/Lib/turtledemo/round_dance.py b/Lib/turtledemo/round_dance.py
new file mode 100644
index 0000000000..10383614c6
--- /dev/null
+++ b/Lib/turtledemo/round_dance.py
@@ -0,0 +1,86 @@
+"""      turtle-example-suite:
+
+         tdemo_round_dance.py
+
+(Needs version 1.1 of the turtle module that
+comes with Python 3.1)
+
+Dancing turtles have a compound shape
+consisting of a series of triangles of
+decreasing size.
+
+Turtles march along a circle while rotating
+pairwise in opposite direction, with one
+exception. Does that breaking of symmetry
+enhance the attractiveness of the example?
+
+Press any key to stop the animation.
+
+Technically: demonstrates use of compound
+shapes, transformation of shapes as well as
+cloning turtles. The animation is
+controlled through update().
+"""
+
+from turtle import *
+
+def stop():
+    global running
+    running = False
+
+def main():
+    global running
+    clearscreen()
+    bgcolor("gray10")
+    tracer(False)
+    shape("triangle")
+    f =   0.793402
+    phi = 9.064678
+    s = 5
+    c = 1
+    # create compound shape
+    sh = Shape("compound")
+    for i in range(10):
+        shapesize(s)
+        p =get_shapepoly()
+        s *= f
+        c *= f
+        tilt(-phi)
+        sh.addcomponent(p, (c, 0.25, 1-c), "black")
+    register_shape("multitri", sh)
+    # create dancers
+    shapesize(1)
+    shape("multitri")
+    pu()
+    setpos(0, -200)
+    dancers = []
+    for i in range(180):
+        fd(7)
+        tilt(-4)
+        lt(2)
+        update()
+        if i % 12 == 0:
+            dancers.append(clone())
+    home()
+    # dance
+    running = True
+    onkeypress(stop)
+    listen()
+    cs = 1
+    while running:
+        ta = -4
+        for dancer in dancers:
+            dancer.fd(7)
+            dancer.lt(2)
+            dancer.tilt(ta)
+            ta = -4 if ta > 0 else 2
+        if cs < 180:
+            right(4)
+            shapesize(cs)
+            cs *= 1.005
+        update()
+    return "DONE!"
+
+if __name__=='__main__':
+    print(main())
+    mainloop()