From c6c21981d06457e08fffc10adaf3cab28f937755 Mon Sep 17 00:00:00 2001
From: Mario Voigt <mario.voigt@stadtfabrikanten.org>
Date: Thu, 8 Jul 2021 13:45:36 +0200
Subject: [PATCH] added polygon side extension

---
 .../polygon_side/polygon_side.inx             |  22 ++++
 .../polygon_side/polygon_side.py              | 118 ++++++++++++++++++
 2 files changed, 140 insertions(+)
 create mode 100755 extensions/fablabchemnitz/polygon_side/polygon_side.inx
 create mode 100644 extensions/fablabchemnitz/polygon_side/polygon_side.py

diff --git a/extensions/fablabchemnitz/polygon_side/polygon_side.inx b/extensions/fablabchemnitz/polygon_side/polygon_side.inx
new file mode 100755
index 00000000..52df43c0
--- /dev/null
+++ b/extensions/fablabchemnitz/polygon_side/polygon_side.inx
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
+    <name>Polygon Side</name>
+    <id>fablabchemnitz.de.polygon_side</id>
+    <param name="number_of_sides" type="int" min="1" max="100" gui-text="Number of Sides">3</param>
+    <param name="length_of_sides" type="float" min="0.01" max="9999" gui-text="Length of Sides">25</param>
+    <param name="unit_choice" type="optiongroup" appearance="radio" gui-text="Units">
+        <option value="1">User</option>
+        <option value="2">Pixels</option>
+    </param>
+    <effect>
+        <object-type>path</object-type>
+        <effects-menu>
+         <submenu name="FabLab Chemnitz">
+            <submenu name="Shape/Pattern from Generator"/>
+         </submenu>
+        </effects-menu>
+    </effect>
+    <script>
+        <command location="inx" interpreter="python">polygon_side.py</command>
+    </script>
+</inkscape-extension>
\ No newline at end of file
diff --git a/extensions/fablabchemnitz/polygon_side/polygon_side.py b/extensions/fablabchemnitz/polygon_side/polygon_side.py
new file mode 100644
index 00000000..95209aaf
--- /dev/null
+++ b/extensions/fablabchemnitz/polygon_side/polygon_side.py
@@ -0,0 +1,118 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) [2021] [Matt Cottam], [mpcottam@raincloud.co.uk]
+#
+# 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.
+#
+#
+# Create a Polygon given a number of sides and side length.
+#
+
+import math
+import inkex
+from inkex import PathElement
+from inkex import units
+import re
+
+# Formula to find the circumradius ( centre to apex ) required to create
+# for a given number of sectors to return desired side length
+
+def radius_from_side_and_sectors(side_length, sectors, found_units, unit_choice):
+    conversions = {
+        'in': 96.0,
+        'pt': 1.3333333333333333,
+        'px': 1.0,
+        'mm': 3.779527559055118,
+        'cm': 37.79527559055118,
+        'm': 3779.527559055118,
+        'km': 3779527.559055118,
+        'Q': 0.94488188976378,
+        'pc': 16.0,
+        'yd': 3456.0,
+        'ft': 1152.0,
+        '': 1.0,  # Default px
+    }
+
+    # Try to convert from detected units into pixels
+
+    if unit_choice == 2:
+        try:
+            pixel_conversion_factor = conversions[found_units]
+        except:
+            pixel_conversion_factor = 1
+
+    else:
+        pixel_conversion_factor = 1
+
+    radius = (side_length / (2 * (math.sin(math.pi / sectors)))) / pixel_conversion_factor
+
+    path = svg_poly(0, 0, radius, sectors)
+
+    return path
+
+
+# All points of a regular polygon lie on a circle
+# Calculate points on circle for given number of sides
+
+def svg_poly(cx, cy, radius, sectors):
+    x_start = cx
+    y_start = cy - radius
+
+    angle = 0
+
+    y_start = cy / 2 + (radius * (math.sin(angle)))
+    x_start = cx / 2 + (radius * (math.cos(angle)))
+
+    path = f'M {x_start} {y_start}'
+
+    for sector in range(1, sectors + 1):
+        angle = (sector * math.pi) / (sectors / 2)
+
+        y = cy / 2 + (radius * (math.sin(angle)))
+        x = cx / 2 + (radius * (math.cos(angle)))
+
+        path = path + f' L {x} {y} '
+
+        x_start = x
+        y_start = y
+
+    return path + ' z'
+
+
+class makepoly(inkex.GenerateExtension):
+
+    def add_arguments(self, pars):
+        pars.add_argument("--number_of_sides", type=int, dest="sectors", default=6)
+        pars.add_argument("--length_of_sides", type=float, dest="side_length", default=25)
+        pars.add_argument("--unit_choice", type=int, dest="unit_choice", default=25)
+
+    container_label = 'Side Poly'
+
+    def generate(self):
+        found_units = self.svg.unit
+
+        path = radius_from_side_and_sectors(self.options.side_length, self.options.sectors, found_units,
+                                            self.options.unit_choice)
+
+        style = {'stroke': '#000000', 'fill': 'none', 'stroke-width': str(self.svg.unittouu('1px'))}
+        poly_path = PathElement()
+        poly_path.style = style
+        poly_path.path = path
+
+        yield poly_path
+
+
+if __name__ == '__main__':
+    makepoly().run()