jpayne@69: """      turtle-example-suite:
jpayne@69: 
jpayne@69:          tdemo_round_dance.py
jpayne@69: 
jpayne@69: (Needs version 1.1 of the turtle module that
jpayne@69: comes with Python 3.1)
jpayne@69: 
jpayne@69: Dancing turtles have a compound shape
jpayne@69: consisting of a series of triangles of
jpayne@69: decreasing size.
jpayne@69: 
jpayne@69: Turtles march along a circle while rotating
jpayne@69: pairwise in opposite direction, with one
jpayne@69: exception. Does that breaking of symmetry
jpayne@69: enhance the attractiveness of the example?
jpayne@69: 
jpayne@69: Press any key to stop the animation.
jpayne@69: 
jpayne@69: Technically: demonstrates use of compound
jpayne@69: shapes, transformation of shapes as well as
jpayne@69: cloning turtles. The animation is
jpayne@69: controlled through update().
jpayne@69: """
jpayne@69: 
jpayne@69: from turtle import *
jpayne@69: 
jpayne@69: def stop():
jpayne@69:     global running
jpayne@69:     running = False
jpayne@69: 
jpayne@69: def main():
jpayne@69:     global running
jpayne@69:     clearscreen()
jpayne@69:     bgcolor("gray10")
jpayne@69:     tracer(False)
jpayne@69:     shape("triangle")
jpayne@69:     f =   0.793402
jpayne@69:     phi = 9.064678
jpayne@69:     s = 5
jpayne@69:     c = 1
jpayne@69:     # create compound shape
jpayne@69:     sh = Shape("compound")
jpayne@69:     for i in range(10):
jpayne@69:         shapesize(s)
jpayne@69:         p =get_shapepoly()
jpayne@69:         s *= f
jpayne@69:         c *= f
jpayne@69:         tilt(-phi)
jpayne@69:         sh.addcomponent(p, (c, 0.25, 1-c), "black")
jpayne@69:     register_shape("multitri", sh)
jpayne@69:     # create dancers
jpayne@69:     shapesize(1)
jpayne@69:     shape("multitri")
jpayne@69:     pu()
jpayne@69:     setpos(0, -200)
jpayne@69:     dancers = []
jpayne@69:     for i in range(180):
jpayne@69:         fd(7)
jpayne@69:         tilt(-4)
jpayne@69:         lt(2)
jpayne@69:         update()
jpayne@69:         if i % 12 == 0:
jpayne@69:             dancers.append(clone())
jpayne@69:     home()
jpayne@69:     # dance
jpayne@69:     running = True
jpayne@69:     onkeypress(stop)
jpayne@69:     listen()
jpayne@69:     cs = 1
jpayne@69:     while running:
jpayne@69:         ta = -4
jpayne@69:         for dancer in dancers:
jpayne@69:             dancer.fd(7)
jpayne@69:             dancer.lt(2)
jpayne@69:             dancer.tilt(ta)
jpayne@69:             ta = -4 if ta > 0 else 2
jpayne@69:         if cs < 180:
jpayne@69:             right(4)
jpayne@69:             shapesize(cs)
jpayne@69:             cs *= 1.005
jpayne@69:         update()
jpayne@69:     return "DONE!"
jpayne@69: 
jpayne@69: if __name__=='__main__':
jpayne@69:     print(main())
jpayne@69:     mainloop()