# L-31 MCS 260 Wed 7 Nov 2007 : pentagram.py
#
# Illustration of canvas: drawing a pentagram.
# The origin is at the top left corner.

from Tkinter import *
from math import *

d = 400      # number of pixels in rows/columns
r = 0.8*d/2  # radius of the pentagram
a = 2*pi/5   # dividing angle
L = [(d/2,d/2-r),\
     (d/2+r*cos(pi/2-a),d/2-r*sin(pi/2-a)),\
     (d/2+r*cos(pi/2-2*a),d/2-r*sin(pi/2-2*a)),\
     (d/2+r*cos(pi/2-3*a),d/2-r*sin(pi/2-3*a)),\
     (d/2+r*cos(pi/2-4*a),d/2-r*sin(pi/2-4*a))]

wdw = Tk()
wdw.title('pentagram')
c = Canvas(wdw,width=d,height=d,bg='white')
c.pack()
for p in L:
   c.create_oval(p[0]-6,p[1]-6,p[0]+6,p[1]+6,\
       width=1,outline='black',fill='SkyBlue2') 
A = L[0]; B = L[1]; C = L[2]; D = L[3]; E = L[4]
c.create_line(A[0],A[1],C[0],C[1],width=2)
c.create_line(A[0],A[1],D[0],D[1],width=2)
c.create_line(B[0],B[1],D[0],D[1],width=2)
c.create_line(B[0],B[1],E[0],E[1],width=2)
c.create_line(C[0],C[1],E[0],E[1],width=2)
wdw.mainloop()