aa438e12142ea72d57451244e869c2246f483d2b
1 #!/usr/bin/env python
2 '''
3 Copyright (C) 2005 Aaron Spike, aaron@ekips.org
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.
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.
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
21 drawwave() was translated into python from the postscript version
22 described at http://www.ghostscript.com/person/toby/ and located
23 at http://www.telegraphics.com.au/sw/sine.ps .
24 http://www.tinaja.com/glib/bezsine.pdf shows another method for
25 approximating sine with beziers.
27 The orginal postscript version displayed the following copyright
28 notice and was released under the terms of the GPL:
29 Copyright (C) 2001-3 Toby Thain, toby@telegraphics.com.au
30 '''
31 import inkex, simplepath, simplestyle
32 from math import *
33 from random import *
35 def drawwave(samples, periods, width, height, left, top,
36 fx = "sin(x)", fpx = "cos(x)", fponum = True):
38 # step is the distance between nodes on x
39 step = 2*pi / samples
40 third = step / 3.0
42 # coords and scales based on the source rect
43 xoff = left
44 yoff = top + (height / 2)
45 scalex = width / (2*pi * periods)
46 scaley = height / 2
47 procx = lambda x: x * scalex + xoff
48 procy = lambda y: y * scaley + yoff
50 # functions specified by the user
51 if fx != "":
52 f = eval('lambda x: ' + fx)
53 if fpx != "":
54 fp = eval('lambda x: ' + fpx)
56 # initialize function and derivative for 0;
57 # they are carried over from one iteration to the next, to avoid extra function calculations
58 y0 = f(0)
59 if fponum == True: # numerical derivative, using 0.001*step as the small differential
60 d0 = (f(0 + 0.001*step) - y0)/(0.001*step)
61 else: # derivative given by the user
62 d0 = fp(0)
64 a = [] # path array
65 a.append(['M',[procx(0.0), procy(y0)]]) # initial moveto
67 for i in range(int(samples * periods)):
68 x = i * step
69 y1 = f(x + step)
70 if fponum == True: # numerical derivative
71 d1 = (y1 - f(x + step - 0.001*step))/(0.001*step)
72 else: # derivative given by the user
73 d1 = fp(x + step)
74 # create curve
75 a.append(['C',[procx(x + third), procy(y0 + (d0 * third)),
76 procx(x + (step - third)), procy(y1 - (d1 * third)),
77 procx(x + step), procy(y1)]])
78 y0 = y1 # next segment's y0 is this segment's y1
79 d0 = d1 # we assume the function is smooth everywhere, so carry over the derivative too
81 return a
83 class Wavy(inkex.Effect):
84 def __init__(self):
85 inkex.Effect.__init__(self)
86 self.OptionParser.add_option("-p", "--periods",
87 action="store", type="float",
88 dest="periods", default=4.0,
89 help="Periods (2*Pi each)")
90 self.OptionParser.add_option("-s", "--samples",
91 action="store", type="int",
92 dest="samples", default=8,
93 help="Samples per period")
94 self.OptionParser.add_option("--fofx",
95 action="store", type="string",
96 dest="fofx", default="sin(x)",
97 help="f(x) for plotting")
98 self.OptionParser.add_option("--fponum",
99 action="store", type="inkbool",
100 dest="fponum", default=True,
101 help="Calculate the first derivative numerically")
102 self.OptionParser.add_option("--fpofx",
103 action="store", type="string",
104 dest="fpofx", default="cos(x)",
105 help="f'(x) for plotting")
106 def effect(self):
107 for id, node in self.selected.iteritems():
108 if node.tagName == 'rect':
109 new = self.document.createElement('svg:path')
110 x = float(node.attributes.getNamedItem('x').value)
111 y = float(node.attributes.getNamedItem('y').value)
112 w = float(node.attributes.getNamedItem('width').value)
113 h = float(node.attributes.getNamedItem('height').value)
115 s = node.attributes.getNamedItem('style').value
116 new.setAttribute('style', s)
117 try:
118 t = node.attributes.getNamedItem('transform').value
119 new.setAttribute('transform', t)
120 except AttributeError:
121 pass
122 new.setAttribute('d', simplepath.formatPath(
123 drawwave(self.options.samples,
124 self.options.periods,
125 w,h,x,y,
126 self.options.fofx,
127 self.options.fpofx,
128 self.options.fponum)))
129 node.parentNode.appendChild(new)
130 node.parentNode.removeChild(node)
132 e = Wavy()
133 e.affect()