share/extensions/fractalize.py

   1 #!/usr/bin/env python
   2 '''
   3 Copyright (C) 2005 Carsten Goetze c.goetze@tu-bs.de
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation; either version 2 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 '''
  19 import random, math, inkex, simplepath
  20
  21 def calculateSubdivision(x1,y1,x2,y2,smoothness):
  22     """ Calculate the vector from (x1,y1) to (x2,y2) """
  23     x3 = x2 - x1
  24     y3 = y2 - y1
  25     """ Calculate the point half-way between the two points """
  26     hx = x1 + x3/2
  27     hy = y1 + y3/2
  28     """ Calculate normalized vector perpendicular to the vector (x3,y3) """
  29     length = math.sqrt(x3*x3 + y3*y3)
  30     if length != 0:
  31         nx = -y3/length
  32         ny = x3/length
  33     else:
  34         nx = 1
  35         ny = 0
  36     """ Scale perpendicular vector by random factor """
  37     r = random.uniform(-length/(1+smoothness),length/(1+smoothness))
  38     nx = nx * r
  39     ny = ny * r
  40     """ add scaled perpendicular vector to the half-way point to get the final
  41         displaced subdivision point """
  42     x = hx + nx
  43     y = hy + ny
  44     return [x, y]
  45
  46 class PathFractalize(inkex.Effect):
  47     def __init__(self):
  48         inkex.Effect.__init__(self)
  49         self.OptionParser.add_option("-s", "--subdivs",
  50                         action="store", type="int",
  51                         dest="subdivs", default="6",
  52                         help="Number of subdivisons")
  53         self.OptionParser.add_option("-f", "--smooth",
  54                         action="store", type="float",
  55                         dest="smooth", default="4.0",
  56                         help="Smoothness of the subdivision")
  57     def effect(self):
  58         for id, node in self.selected.iteritems():
  59             if node.tag == inkex.addNS('path','svg'):
  60                 d = node.get('d')
  61                 p = simplepath.parsePath(d)
  62
  63                 a = []
  64                 first = 1
  65                 for cmd,params in p:
  66                     if cmd != 'Z':
  67                         if first == 1:
  68                             x1 = params[-2]
  69                             y1 = params[-1]
  70                             a.append(['M',params[-2:]])
  71                             first = 2
  72                         else :
  73                             x2 = params[-2]
  74                             y2 = params[-1]
  75                             self.fractalize(a,x1,y1,x2,y2,self.options.subdivs,self.options.smooth)
  76                             x1 = x2
  77                             y1 = y2
  78                             a.append(['L',params[-2:]])
  79
  80                 node.set('d', simplepath.formatPath(a))
  81
  82     def fractalize(self,a,x1,y1,x2,y2,s,f):
  83         subdivPoint = calculateSubdivision(x1,y1,x2,y2,f)
  84
  85         if s > 0 :
  86             """ recursively subdivide the segment left of the subdivision point """
  87             self.fractalize(a,x1,y1,subdivPoint[-2],subdivPoint[-1],s-1,f)
  88             a.append(['L',subdivPoint])
  89             """ recursively subdivide the segment right of the subdivision point """
  90             self.fractalize(a,subdivPoint[-2],subdivPoint[-1],x2,y2,s-1,f)
  91
  92 if __name__ == '__main__':
  93     e = PathFractalize()
  94     e.affect()
  95
  96
  97 # vim: expandtab shiftwidth=4 tabstop=8 softtabstop=4 fileencoding=utf-8 textwidth=99