1 files changed, 88 insertions, 0 deletions
diff --git a/share/extensions/render_gear_rack.py b/share/extensions/render_gear_rack.py
new file mode 100755
index 0000000..229713c
--- /dev/null
+++ b/share/extensions/render_gear_rack.py
@@ -0,0 +1,88 @@
+#!/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()