#Sinewheel hip-pocket program in Python/Tkinter
#William Baker, Summer 2004, illiMath04 Program
#Adapted from Math198 course notes by Prof. George Francis
#University of Illinois Urbana-Champaign Dept. of Mathematics
#Edited by GF 19sep09

import Tkinter   # 2D drawing package for Python
import math      # all the math you'll likely need
import time      # for pauses and delays

defaldelay=4     #default delay time controls animation speed

#createLine()    #pronounce  "creatLine function"
#Draws a red line segment between the specified coordinates
def createLine(x0, y0, x1, y1):
   canvas.create_line(x0, y0, x1, y1, fill="red")

#startAnimation()
#Performs the animation when called by the clicking start button
#Translate the BASIC program into this function
def startAnimation():
   dg = .01745  # one degree in radians
   dx = 6       # step size 
   r = 75       # circle radius
   x0=80        # location of origin 
   y0=240       # location of origin 
   x=0          # arclength parameter
   for x in range(0, 361, dx): 
      xr = x0+r*math.cos(x*dg)       # end of radius on circle
      yr = y0-r*math.sin(x*dg)   
      xx = x0+r+r*x*dg               # mystery variable 

      createLine(x0,y0,xr,yr)
      createLine(xr,yr,xx,yr)
      createLine(xx,yr,xx,y0)      

      canvas.update()                # swap buffers
      time.sleep(int(timedelay.get())/20.0) # slow animation

#clear()
#Clears the cavas, called when clear button is clicked
def clear():
    canvas.delete("all")

# Implementation of the above program in TkInter 
window = Tkinter.Tk()
window.title("Sinewheel in Python/Tkinter")
clear_button = Tkinter.Button(window, text = "Clear", command = clear)
start = Tkinter.Button(window, text="Start", command=startAnimation)
delLabel=Tkinter.Label(window, width="15")
delLabel.configure(text="Time Delay= ")
timedelay=Tkinter.StringVar()
timedelay.set(`defaldelay`)
delentry = Tkinter.Entry(window, width="15", textvariable=timedelay)
canvas = Tkinter.Canvas(window, width=640, height=480)
canvas.pack(side="top")
delLabel.pack(side="left")
delentry.pack(side="left")
start.pack(side="right")
clear_button.pack(side = "right")
# start event loop
window.mainloop()