gallery/misc/julia.py

   1 # contributed by Stefan Schenk
   2
   3 from cStringIO import StringIO
   4 from math import sqrt
   5 from pyx import *
   6
   7 xiterations = yiterations = 250
   8 Min_Im = -1.5
   9 Max_Im = 1.5
  10 Min_Re = -1.5
  11 Max_Re = 1.5
  12 c = 0.41 + 0.3j
  13 p = color.palette.RedBlue
  14
  15 def rgbcolortostring(c):
  16     return "".join([chr(int(255*c.color[name])) for name in "rgb"])
  17
  18 data = StringIO()
  19
  20 # compute fractal
  21 for y in range(yiterations):
  22     for x in range(xiterations):
  23         z = complex(1.0*(Max_Re-Min_Re)*x/xiterations + Min_Re,
  24                     1.0*(Max_Im-Min_Im)*y/yiterations + Min_Im)
  25
  26         for k in range(256):
  27             z = z*z + c
  28             if abs(z) > 2:
  29                 # append color(RGB) of the current pixel to the end of data
  30                 data.write(rgbcolortostring(p.getcolor(1.0/sqrt(k+1))))
  31                 break
  32         else:
  33             data.write("\0\0\0")
  34
  35 # generate image from data
  36 julia = bitmap.image(xiterations, yiterations, "RGB", data.getvalue())
  37 juliabitmap = bitmap.bitmap(0, 0, julia, height=10)
  38
  39 c = canvas.canvas()
  40 c.insert(juliabitmap)
  41 c.writeEPSfile("julia")
  42 c.writePDFfile("julia")