Wavy
" RFE #1124104: sine tool" was one of the reasons I thought it would be fun to work on extensions. This script is my implementation of a sine wave tool for Inkscape. It replaces any selected "rect" elements with a sine wave of the specified length. Specifying functions other that sin(x) is also possible. I got visually interesting results by accidentally passing degrees instead of radians to sin(x).
#!/usr/bin/env python ''' Copyright (C) 2005 Aaron Spike, ACSpike@hotmail.com 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 drawwave() was translated into python from the postscript version described at http://www.ghostscript.com/person/toby/ and located at http://www.telegraphics.com.au/sw/sine.ps . http://www.tinaja.com/glib/bezsine.pdf shows another method for approximating sine with beziers. The orginal postscript version displayed the following copyright notice and was released under the terms of the GPL: Copyright (C) 2001-3 Toby Thain, toby@telegraphics.com.au ''' import math, inkex def drawwave(period, length, width, height, left, top, fx = "lambda x: math.sin(x)", fpx = "lambda x: math.cos(x)"): step = math.pi / period third = step / 3.0 xoff = left yoff = top + (height / 2) scalex = width / (step * length) scaley = height / 2 procx = lambda x: x * scalex + xoff procy = lambda y: y * scaley + yoff f = eval(fx) fp = eval(fpx) a = [] a.append(['M',[procx(0.0), procy(f(0))]]) for i in range(length): x = i * step a.append(['C',[procx(x + third), procy(f(x) + (fp(x) * third)), procx(x + (step - third)), procy(f(x + step) - (fp(x + step) * third)), procx(x + step), procy(f(x + step))]]) return a class Wavy(inkex.Effect): def __init__(self): inkex.Effect.__init__(self) self.OptionParser.add_option("-p", "--period", action="store", type="float", dest="period", default=4.0, help="pi/period interval between samples") self.OptionParser.add_option("-l", "--length", action="store", type="int", dest="length", default=8, help="length of the curve in periods") self.OptionParser.add_option("--fofx", action="store", type="string", dest="fofx", default="lambda x: math.sin(x)", help="lambda form of f(x) for plotting") self.OptionParser.add_option("--fpofx", action="store", type="string", dest="fpofx", default="lambda x: math.cos(x)", help="lambda form of f'(x) for plotting") def effect(self): for id, node in self.selected.iteritems(): if node.tagName == 'rect': x = float(node.attributes.getNamedItem('x').value) y = float(node.attributes.getNamedItem('y').value) w = float(node.attributes.getNamedItem('width').value) h = float(node.attributes.getNamedItem('height').value) 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', inkex.formatStyle(s)) new.setAttribute('d', inkex.formatPath( drawwave(self.options.period, self.options.length, w,h,x,y, self.options.fofx, self.options.fpofx))) node.parentNode.appendChild(new) node.parentNode.removeChild(node) e = Wavy() e.affect()
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