gallery/path/tree.py

   1 # -*- coding: ISO-8859-1 -*-
   2 # fractal tree
   3 # contributed by Gerhard Schmid and André Wobst
   4
   5 from pyx import *
   6
   7 # base tree length
   8 l = 5
   9
  10 # base transformations for the left, center, and right part of the tree
  11 ltrafo = trafo.rotate(65).scaled(0.4).translated(0, l * 2.0 / 3.0)
  12 ctrafo = trafo.rotate(-4).scaled(0.75).translated(0, l)
  13 rtrafo = trafo.mirror(90).rotated(-65).scaled(0.35).translated(0, l)
  14
  15 def tree(depth):
  16     "return transformations for a recursive tree of given depth"
  17     r = [trafo.rotate(5)]
  18     if depth > 0:
  19         subtree = tree(depth - 1)
  20         r.extend([t*ltrafo for t in subtree])
  21         r.extend([t*ctrafo for t in subtree])
  22         r.extend([t*rtrafo for t in subtree])
  23     return r
  24
  25 c = canvas.canvas()
  26 for t in tree(7):
  27     # apply the transformation to a "sub"-canvas and insert it into the "main" canvas
  28     c.insert(canvas.canvas([t])).stroke(path.line(0, 0, 0, l))
  29     # note that there is a difference when only transforming the line as in:
  30     # c.stroke(path.line(0, 0, 0, l), [t])
  31     # The difference is, that the linewidth would not be scaled down.
  32 c.writeEPSfile("tree")
  33 c.writePDFfile("tree")