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#!/usr/bin/env python
# coding=utf-8
#
# Copyright (C) 2009 Michel Chatelain.
# 2007 Tavmjong Bah, tavmjong@free.fr
# 2006 Georg Wiora, xorx@quarkbox.de
# 2006 Johan Engelen, johan@shouraizou.nl
# 2005 Aaron Spike, aaron@ekips.org
#
# 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
# Changes:
# * This program is derived by Michel Chatelain from funcplot.py.
# His changes are in the Public Domain.
# * Michel Chatelain, 17-18 janvier 2009, a partir de funcplot.py
# * 20 janvier 2009 : adaptation a la version 0.46 a partir de la nouvelle version de funcplot.py
#
"""
Parametric Curves has no real description, even in the inx file, which is really odd.
"""
from math import pi, cos, sin, tan
import inkex
def maths_eval(user_function):
"""Try and make the eval safer"""
func = 'lambda t: ' + (user_function.strip('"') or 't')
return eval( # pylint: disable=eval-used
func,
{
'pi': pi, 'sin': sin, 'cos': cos, 'tan': tan,
}, {})
def drawfunction(t_start, t_end, xleft, xright, ybottom, ytop, samples, width, height, left, bottom,
fx="cos(3*t)", fy="sin(5*t)", times2pi=False, isoscale=True, drawaxis=True):
if times2pi:
t_start *= 2 * pi
t_end *= 2 * pi
# coords and scales based on the source rect
scalex = width / (xright - xleft)
xoff = left
coordx = lambda x: (x - xleft) * scalex + xoff # convert x-value to coordinate
scaley = height / (ytop - ybottom)
yoff = bottom
coordy = lambda y: (ybottom - y) * scaley + yoff # convert y-value to coordinate
# Check for isotropic scaling and use smaller of the two scales, correct ranges
if isoscale:
if scaley < scalex:
# compute zero location
xzero = coordx(0)
# set scale
scalex = scaley
# correct x-offset
xleft = (left - xzero) / scalex
xright = (left + width - xzero) / scalex
else:
# compute zero location
yzero = coordy(0)
# set scale
scaley = scalex
# correct x-offset
ybottom = (yzero - bottom) / scaley
ytop = (bottom + height - yzero) / scaley
# functions specified by the user
f1 = maths_eval(fx)
f2 = maths_eval(fy)
# step is increment of t
step = (t_end - t_start) / (samples - 1)
third = step / 3.0
ds = step * 0.001 # Step used in calculating derivatives
a = [] # path array
# add axis
if drawaxis:
# check for visibility of x-axis
if ybottom <= 0 <= ytop:
# xaxis
a.append(['M', [left, coordy(0)]])
a.append(['l', [width, 0]])
# check for visibility of y-axis
if xleft <= 0 <= xright:
# xaxis
a.append(['M', [coordx(0), bottom]])
a.append(['l', [0, -height]])
# initialize functions and derivatives for 0;
# they are carried over from one iteration to the next, to avoid extra function calculations.
#print("RET: {}".format(f1(1)))
x0 = f1(t_start)
y0 = f2(t_start)
# numerical derivatives, using 0.001*step as the small differential
t1 = t_start + ds # Second point AFTER first point (Good for first point)
x1 = f1(t1)
y1 = f2(t1)
dx0 = (x1 - x0) / ds
dy0 = (y1 - y0) / ds
# Start curve
a.append(['M', [coordx(x0), coordy(y0)]]) # initial moveto
for i in range(int(samples - 1)):
t1 = (i + 1) * step + t_start
t2 = t1 - ds # Second point BEFORE first point (Good for last point)
x1 = f1(t1)
x2 = f1(t2)
y1 = f2(t1)
y2 = f2(t2)
# numerical derivatives
dx1 = (x1 - x2) / ds
dy1 = (y1 - y2) / ds
# create curve
a.append(['C',
[coordx(x0 + (dx0 * third)), coordy(y0 + (dy0 * third)),
coordx(x1 - (dx1 * third)), coordy(y1 - (dy1 * third)),
coordx(x1), coordy(y1)]
])
t0 = t1 # Next segment's start is this segments end
x0 = x1
y0 = y1
dx0 = dx1 # Assume the functions are smooth everywhere, so carry over the derivatives too
dy0 = dy1
return a
class ParamCurves(inkex.EffectExtension):
def add_arguments(self, pars):
pars.add_argument("--t_start", type=float, default=0.0, help="Start t-value")
pars.add_argument("--t_end", type=float, default=1.0, help="End t-value")
pars.add_argument("--times2pi", type=inkex.Boolean, default=True,
help="Multiply t-range by 2*pi")
pars.add_argument("--xleft", type=float, default=-1.0, help="x-value of left")
pars.add_argument("--xright", type=float, default=1.0, help="x-value of right")
pars.add_argument("--ybottom", type=float, default=-1.0, help="y-value of bottom")
pars.add_argument("--ytop", type=float, default=1.0, help="y-value of top")
pars.add_argument("-s", "--samples", type=int, default=8, help="Samples")
pars.add_argument("--fofx", default="cos(3*t)", help="fx(t) for plotting")
pars.add_argument("--fofy", default="sin(5*t)", help="fy(t) for plotting")
pars.add_argument("--remove", type=inkex.Boolean, default=True, help="Remove rectangle")
pars.add_argument("--isoscale", type=inkex.Boolean, default=True, help="Isotropic scaling")
pars.add_argument("--drawaxis", type=inkex.Boolean, default=True)
pars.add_argument("--tab", default="sampling")
def effect(self):
for node in self.svg.selected.values():
if isinstance(node, inkex.Rectangle):
# create new path with basic dimensions of selected rectangle
newpath = inkex.PathElement()
x = float(node.get('x'))
y = float(node.get('y'))
width = float(node.get('width'))
height = float(node.get('height'))
# copy attributes of rect
newpath.style = node.style
newpath.transform = node.transform
# top and bottom were exchanged
newpath.path = \
drawfunction(self.options.t_start,
self.options.t_end,
self.options.xleft,
self.options.xright,
self.options.ybottom,
self.options.ytop,
self.options.samples,
width, height, x, y + height,
self.options.fofx,
self.options.fofy,
self.options.times2pi,
self.options.isoscale,
self.options.drawaxis)
newpath.set('title', self.options.fofx + " " + self.options.fofy)
# newpath.set('desc', '!func;' + self.options.fofx + ';' + self.options.fofy + ';'
# + `self.options.t_start` + ';'
# + `self.options.t_end` + ';'
# + `self.options.samples`)
# add path into SVG structure
node.getparent().append(newpath)
# option whether to remove the rectangle or not.
if self.options.remove:
node.getparent().remove(node)
if __name__ == '__main__':
ParamCurves().run()
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