turtle_recursion.py

"""
For recursively drawing turtle functions

Samantha Goldstein

  April, 2012
"""
import turtle

def main():
  turtle.setup(width= 500, height= 500)
  turtle.up()

  levels = input("How many levels?: ")
  turtle.setpos(-250, 0)
  #turtle.setpos(0, -250)
  turtle.down()
  #levels = 3
  line_size = float(turtle.window_width())/3**levels
  line_size2 = float(turtle.window_width())/(2**(levels+1)-1)
  #turtle.setheading(90)
  #turtle.setpos(0,0)
  #drawCodestring("F[-F]+F", turtle, 50, 30)
  cdstring = koch_production("F", levels)
  #cdstring = shrub_production("F", levels)
  
  #drawCodestring(cdstring, turtle, line_size2, 25)
  drawCodestring(cdstring, turtle, line_size, 60)
  turtle.hideturtle()

  turtle.exitonclick()



def drawCodestring(cdstring, trtl, size, agl):
  state = []
  

  for i in range(len(cdstring)):
    if cdstring[i] == 'F':
      trtl.forward(size)
    elif cdstring[i] == '-':
      trtl.left(agl)
    elif cdstring[i] == '+':
      trtl.right(agl)
    elif cdstring[i] == '[':
      pos = trtl.pos()
      head = trtl.heading()
      state.append([head, pos])
    elif cdstring[i] == ']':
      head, pos = state.pop()
      trtl.up()
      trtl.setpos(pos)
      trtl.down()
      trtl.setheading(head)

  return

def koch_production(codestring, n):
  
  if n == 0:
    #return "F"
    return codestring
  else:
    cd = ""
    #codestring = list(codestring)
    for i in range(len(codestring)):
      if codestring[i] == "F":
        cd = cd + "F-F++F-F"
      else:
        cd = cd + codestring[i]

    #for i in range(1,len(codestring)):
      #codestring[0] = codestring[0] + codestring[i]

    #print 
    #return koch_production(codestring[0], n-1)
    return koch_production(cd, n-1)

def shrub_production(codestring, n):
  if n == 0:
    return codestring
  else:
    codestring = list(codestring)
    for i in range(len(codestring)):
      if codestring[i] == "F":
        codestring[i] = "F[-F]F[+F][F]"
    for i in range(1, len(codestring)):
      codestring[0] = codestring[0] + codestring[i]

    return shrub_production(codestring[0], n-1)




main()