77 lines
3.6 KiB
Python
77 lines
3.6 KiB
Python
#!/usr/bin/env python3
|
|
"""
|
|
Derived from the "envelope" extension by Aaron Spike, aaron@ekips.org
|
|
By Apex 2011
|
|
New version Jens Kober 2017, 2020
|
|
|
|
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
|
|
from inkex.localization import inkex_gettext as _
|
|
|
|
class Mirror(inkex.EffectExtension):
|
|
|
|
def effect(self):
|
|
if len(self.options.ids) < 2:
|
|
raise inkex.AbortExtension(_("This extension requires two selected objects. \nThe second must be a path, exactly two nodes long."))
|
|
|
|
#trafo is selected second
|
|
obj = self.svg.selected[self.options.ids[0]]
|
|
trafo = self.svg.selected[self.options.ids[1]]
|
|
|
|
if isinstance(trafo, inkex.PathElement):
|
|
#distil trafo into two node points
|
|
trafoPath = trafo.path.transform(trafo.composed_transform()).to_superpath()
|
|
if len(trafoPath[0]) != 2:
|
|
raise inkex.AbortExtension(_("The second selected object must be exactly two nodes long."))
|
|
|
|
# origin of mirror line
|
|
ox = trafoPath[0][0][1][0]
|
|
oy = trafoPath[0][0][1][1]
|
|
# vector along mirror line
|
|
vx = trafoPath[0][1][1][0] - ox
|
|
vy = trafoPath[0][1][1][1] - oy
|
|
|
|
# the transformation first translates the origin of the mirror line to [0 0], then rotates the mirror line onto the x-axis,
|
|
# reflects everything over the x-axis, undoes the rotation, and finally undoes the translation
|
|
|
|
# alpha = atan2(vy, vx);
|
|
|
|
# [1 0 ox] [cos(alpha) -sin(alpha) 0] [1 0 0] [cos(-alpha) -sin(-alpha) 0] [1 0 -ox]
|
|
# Transformation = [0 1 oy]*[sin(alpha) cos(alpha) 0]*[0 -1 0]*[sin(-alpha) cos(-alpha) 0]*[0 1 -oy]
|
|
# [0 0 1] [ 0 0 1] [0 0 1] [ 0 0 1] [0 0 1]
|
|
|
|
# after some simplifications (or using your favorite symbolic math software):
|
|
|
|
# [(vx^2-vy^2)/(vx^2+vy^2) (2 vx vy)/(vx^2+vy^2) (2 vy (ox vy-oy vx))/(vx^2+vy^2)]
|
|
# Transformation = [ (2 vx vy)/(vx^2+vy^2) -(vx^2-vy^2)/(vx^2+vy^2) -(2 vx (ox vy-oy vx))/(vx^2+vy^2)]
|
|
# [ 0 0 1]
|
|
|
|
denom = vx**2 + vy**2
|
|
a00 = (vx**2 - vy**2) / denom
|
|
a01 = (2 * vx * vy) / denom
|
|
a02 = 2 * (ox * vy - oy * vx) / denom
|
|
mat=[[a00, a01, vy * a02], [a01, -a00, -vx * a02]]
|
|
obj.transform = inkex.Transform(mat) * obj.transform
|
|
|
|
else:
|
|
if isinstance(trafo, inkex.Group):
|
|
raise inkex.AbortExtension(_("The second selected object is a group, not a path.\nTry using the procedure Object->Ungroup."))
|
|
else:
|
|
raise inkex.AbortExtension(_("The second selected object is not a path.\nTry using the procedure Path->Object to Path."))
|
|
|
|
if __name__ == '__main__':
|
|
Mirror().run() |