96 lines
3.4 KiB
Python
96 lines
3.4 KiB
Python
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#!/usr/bin/env python3
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import inkex
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from lxml import etree
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from math import cos, sin, pi, exp
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__version__ = '0.1'
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def line(npts=40, x0=0, y0=0, delta=.5, sgn=1):
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#returns a list of points on a line (y = +/- x + c) starting at x0,y0
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return [ (x0 + delta*t, y0 + sgn*delta*t) for t in range(npts)]
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def ff(v, ww=.25, ds=.4):
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#covering map from R^2 ro punctured plane
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x,y = v
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r,u = exp(-ds*x), cos(pi*ww*y) + 1J*sin(pi*ww*y)
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return r*u
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def mk_plugs(pts):
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#returns a list of complex representing a plug type segment
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segs = [fit_plug(end_pts) for end_pts in zip(pts,pts[1:]) ]
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tmp = []
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for seg in segs:
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tmp.extend(seg)
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return tmp
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def fit_plug(ss):
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a,b = ss
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rot = complex(b-a)
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pts = [0,.45,.4 + .15*1J, .6 + .15*1J, .55, 1]
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return [rot*z + a for z in pts]
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def pts2curve(cplxs):
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'''makes a polyline path element from a list of complex
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'''
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def cplx2pt(z):
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return (z.real,z.imag)
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scale = 200
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data = [cplx2pt( scale*z ) for z in cplxs ]
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pth = [ '%.2f, %.2f '%z for z in data]
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return 'M '+ ''.join(pth)
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class AffineSpirals(inkex.EffectExtension):
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def add_arguments(self, pars):
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pars.add_argument("--num_lines", type=int, default=3)
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pars.add_argument("--num_petals", type=int, default=3)
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pars.add_argument("--shrink_ratio", type=float, default=3)
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pars.add_argument("--active-tab", default='title')
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def calc_unit_factor(self):
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unit_factor = self.svg.unittouu(str(1.0) + self.options.units)
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return unit_factor
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def effect(self):
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path_stroke = '#DD0000' # take color from tab3
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path_fill = 'none' # no fill - just a line
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path_stroke_width = 1. # can also be in form '0.6mm'
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page_id = self.options.active_tab # sometimes wrong the very first time
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styles = [ {'stroke': path_stroke , 'fill': 'none', 'stroke-width': path_stroke_width},
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{'stroke': 'none', 'fill': '#FFFF00', 'stroke-width': 0}]
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styles = [str(inkex.Style(x)) for x in styles]
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# This finds center of current view in inkscape
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t = 'translate(%s,%s)' % (self.svg.namedview.center[0], self.svg.namedview.center[1])
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# Make a nice useful name
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g_attribs = {inkex.addNS('label','inkscape'): 'koch',
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inkex.addNS('transform-center-x','inkscape'): str(0),
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inkex.addNS('transform-center-y','inkscape'): str(0),
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'transform': t,
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'style' : styles[1],
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'info':'N: '+str(self.options.num_lines) }
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topgroup = etree.SubElement(self.svg.get_current_layer(), 'g', g_attribs)
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NN = 2*self.options.num_lines
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NP = self.options.num_petals
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SF = 2*self.options.shrink_ratio
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payload = []
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for y in range(-NP,NP):
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mpts = [ff(z,ww=1./NP, ds=SF) for z in line(npts=NN, y0=y)]
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payload.append(mk_plugs(mpts))
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mpts = [ff(z,ww=1./NP, ds=SF) for z in line(npts=NN, y0=y,sgn=-1 )]
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payload.append(mk_plugs(mpts))
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payload = [pts2curve(cc) for cc in payload]
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payload = ' '.join(payload)
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curve_attribs = { 'style': styles[0], 'd': payload}
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etree.SubElement(topgroup, inkex.addNS('path','svg'), curve_attribs)
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if __name__ == '__main__':
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AffineSpirals().run()
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