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-rwxr-xr-xshare/extensions/render_gear_rack.py88
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diff --git a/share/extensions/render_gear_rack.py b/share/extensions/render_gear_rack.py
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+#!/usr/bin/env python
+#
+# Copyright (C) 2013 Brett Graham (hahahaha @ hahaha.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.
+#
+"""
+Generate a gear rack as SVG.
+"""
+
+from math import acos, cos, radians, sin, sqrt, tan
+
+import inkex
+
+
+def involute_intersect_angle(Rb, R):
+ Rb, R = float(Rb), float(R)
+ return (sqrt(R**2 - Rb**2) / Rb) - (acos(Rb / R))
+
+
+def point_on_circle(radius, angle):
+ x = radius * cos(angle)
+ y = radius * sin(angle)
+ return x, y
+
+
+def points_to_svgd(p):
+ """
+ p: list of 2 tuples (x, y coordinates)
+ """
+ f = p[0]
+ p = p[1:]
+ svgd = "M{:.3f},{:.3f}".format(f[0], f[1])
+ for x in p:
+ svgd += "L{:.3f},{:.3f}".format(x[0], x[1])
+ return svgd
+
+
+class RackGear(inkex.GenerateExtension):
+ container_label = "Rendered Gear Rack"
+
+ def add_arguments(self, pars):
+ pars.add_argument("--length", type=float, default=100.0, help="Rack Length")
+ pars.add_argument("--spacing", type=float, default=10.0, help="Tooth Spacing")
+ pars.add_argument("--angle", type=float, default=20.0, help="Contact Angle")
+
+ def generate(self):
+ length = self.svg.unittouu(str(self.options.length) + "px")
+ spacing = self.svg.unittouu(str(self.options.spacing) + "px")
+ angle = radians(self.options.angle)
+
+ # generate points: list of (x, y) pairs
+ points = []
+ x = 0
+ tas = tan(angle) * spacing
+ while x < length:
+ # move along path, generating the next 'tooth'
+ points.append((x, 0))
+ points.append((x + tas, spacing))
+ points.append((x + spacing, spacing))
+ points.append((x + spacing + tas, 0))
+ x += spacing * 2.0
+
+ path = points_to_svgd(points)
+
+ # Create SVG Path for gear
+ style = {
+ "stroke": "#000000",
+ "fill": "none",
+ "stroke-width": str(self.svg.unittouu("1px")),
+ }
+ yield inkex.PathElement(style=str(inkex.Style(style)), d=str(path))
+
+
+if __name__ == "__main__":
+ RackGear().run()