dragon.py

#!/usr/bin/env python

import Image,ImageDraw
import math

PI = math.pi
SQRT2 = math.sqrt(2)
xpos = 0
ypos = 0

def dragon(draw,order,length,angle,sign):
  if not order :
    global xpos,ypos
    gx = xpos+length*math.cos(angle)
    gy = ypos+length*math.sin(angle)
    draw.line([(xpos,ypos),(gx,gy)],fill=0)
    xpos = gx
    ypos = gy
  else :
    dragon(draw,order-1, length/SQRT2, angle-sign*PI/4, -1.0)
    dragon(draw,order-1, length/SQRT2, angle+sign*PI/4,  1.0)


if __name__ == '__main__' :

  im = Image.new("L",(300,300),255)
  draw = ImageDraw.Draw(im)
  xpos = 100
  ypos = 175
  dragon(draw,order=10,length=100,angle=0,sign=1)
  im.show()
  im.save("dragon.png","PNG")