spirograph.py revision 79ec30eb098ea1053718e7b5b0e92b8ff59488a2
#!/usr/bin/env python
'''
Copyright (C) 2007 Joel Holdsworth joel@airwebreathe.org.uk
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
'''
import inkex, simplestyle, math
class Spirograph(inkex.Effect):
def __init__(self):
inkex.Effect.__init__(self)
self.OptionParser.add_option("-R", "--primaryr",
action="store", type="float",
dest="primaryr", default=60.0,
help="The radius of the outer gear")
self.OptionParser.add_option("-r", "--secondaryr",
action="store", type="float",
dest="secondaryr", default=100.0,
help="The radius of the inner gear")
self.OptionParser.add_option("-d", "--penr",
action="store", type="float",
dest="penr", default=50.0,
help="The distance of the pen from the inner gear")
self.OptionParser.add_option("-p", "--gearplacement",
action="store", type="string",
dest="gearplacement", default=50.0,
help="Selects whether the gear is inside or outside the ring")
self.OptionParser.add_option("-a", "--rotation",
action="store", type="float",
dest="rotation", default=100.0,
help="The number of degrees to rotate the image by")
self.OptionParser.add_option("-q", "--quality",
action="store", type="int",
dest="quality", default=16,
help="The quality of the calculated output")
def effect(self):
if self.options.secondaryr == 0:
return
if self.options.quality == 0:
return
if(self.options.gearplacement.strip(' ').lower().startswith('outside')):
a = self.options.primaryr + self.options.secondaryr
flip = -1
else:
a = self.options.primaryr - self.options.secondaryr
flip = 1
ratio = a / self.options.secondaryr
if ratio == 0:
return
scale = 2 * math.pi / (ratio * self.options.quality)
rotation = 2 * math.pi * self.options.rotation / 180;
new = self.document.createElement('svg:path')
s = {'stroke-linejoin': 'miter', 'stroke-width': '1.0px',
'stroke-opacity': '1.0', 'fill-opacity': '1.0',
'stroke': '#000000', 'stroke-linecap': 'butt',
'fill': 'none'}
new.setAttribute('style', simplestyle.formatStyle(s))
pathString = ''
maxPointCount = 1000
for i in range(maxPointCount):
theta = i * scale
x = a * math.cos(theta + rotation) + \
self.options.penr * math.cos(ratio * theta + rotation) * flip + \
self.view_center[0]
y = a * math.sin(theta + rotation) - \
self.options.penr * math.sin(ratio * theta + rotation) + \
self.view_center[1]
dx = (-a * math.sin(theta + rotation) - \
ratio * self.options.penr * math.sin(ratio * theta + rotation) * flip) * scale / 3
dy = (a * math.cos(theta + rotation) - \
ratio * self.options.penr * math.cos(ratio * theta + rotation)) * scale / 3
if i <= 0:
pathString += 'M ' + str(x) + ',' + str(y) + ' C ' + str(x + dx) + ',' + str(y + dy) + ' '
else:
pathString += str(x - dx) + ',' + str(y - dy) + ' ' + str(x) + ',' + str(y)
if math.fmod(i / ratio, self.options.quality) == 0 and i % self.options.quality == 0:
pathString += 'Z'
break
else:
if i == maxPointCount - 1:
pass # we reached the allowed maximum of points, stop here
else:
pathString += ' C ' + str(x + dx) + ',' + str(y + dy) + ' '
new.setAttribute('d', pathString)
self.current_layer.appendChild(new)
e = Spirograph()
e.affect()