share/extensions/rubberstretch.py

   1 #!/usr/bin/env python
   2 '''
   3 Copyright (C) 2006 Jean-Francois Barraud, barraud@math.univ-lille1.fr
   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 barraud@math.univ-lille1.fr
  19
  20 '''
  21
  22 import inkex, cubicsuperpath, bezmisc, pathmodifier
  23 import copy, math, re
  24
  25 class RubberStretch(pathmodifier.Diffeo):
  26     def __init__(self):
  27         pathmodifier.Diffeo.__init__(self)
  28         self.OptionParser.add_option("-r", "--ratio",
  29                         action="store", type="float",
  30                         dest="ratio", default=0.5)
  31         self.OptionParser.add_option("-c", "--curve",
  32                         action="store", type="float",
  33                         dest="curve", default=0.5)
  34
  35     def applyDiffeo(self,bpt,vects=()):
  36         for v in vects:
  37             v[0]-=bpt[0]
  38             v[1]-=bpt[1]
  39             v[1]*=-1
  40         bpt[1]*=-1
  41         a=self.options.ratio/100
  42         b=min(self.options.curve/100,0.99)
  43         x0= (self.bbox[0]+self.bbox[1])/2
  44         y0=-(self.bbox[2]+self.bbox[3])/2
  45         w,h=(self.bbox[1]-self.bbox[0])/2,(self.bbox[3]-self.bbox[2])/2
  46
  47         x,y=(bpt[0]-x0),(bpt[1]-y0)
  48         sx=(1+b*(x/w+1)*(x/w-1))*2**(-a)
  49         sy=(1+b*(y/h+1)*(y/h-1))*2**(-a)
  50         bpt[0]=x0+x*sy
  51         bpt[1]=y0+y/sx
  52         for v in vects:
  53             dx,dy=v
  54             dXdx=sy
  55             dXdy= x*2*b*y/h/h*2**(-a)
  56             dYdx=-y*2*b*x/w/w*2**(-a)/sx/sx
  57             dYdy=1/sx
  58             v[0]=dXdx*dx+dXdy*dy
  59             v[1]=dYdx*dx+dYdy*dy
  60
  61         #--spherify
  62         #s=((x*x+y*y)/(w*w+h*h))**(-a/2)
  63         #bpt[0]=x0+s*x
  64         #bpt[1]=y0+s*y
  65         #for v in vects:
  66         #    dx,dy=v
  67         #    v[0]=(1-a/2/(x*x+y*y)*2*x*x)*s*dx+( -a/2/(x*x+y*y)*2*y*x)*s*dy
  68         #    v[1]=( -a/2/(x*x+y*y)*2*x*y)*s*dx+(1-a/2/(x*x+y*y)*2*y*y)*s*dy
  69
  70         for v in vects:
  71             v[0]+=bpt[0]
  72             v[1]+=bpt[1]
  73             v[1]*=-1
  74         bpt[1]*=-1
  75
  76 e = RubberStretch()
  77 e.affect()
  78
  79
  80 # vim: expandtab shiftwidth=4 tabstop=8 softtabstop=4 encoding=utf-8 textwidth=99