1 files changed, 69 insertions, 0 deletions
diff --git a/share/extensions/whirl.py b/share/extensions/whirl.py
new file mode 100755
index 0000000..f347f61
--- /dev/null
+++ b/share/extensions/whirl.py
@@ -0,0 +1,69 @@
+#!/usr/bin/env python
+# coding=utf-8
+#
+# Copyright (C) 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.
+#
+"""Whirl path extension (modify path)"""
+
+import math
+import inkex
+
+
+class Whirl(inkex.EffectExtension):
+    """Modify a path by twisting the nodes around a point"""
+
+    def add_arguments(self, pars):
+        pars.add_argument(
+            "-t", "--whirl", type=float, default=5.0, help="amount of whirl"
+        )
+        pars.add_argument(
+            "-r",
+            "--rotation",
+            type=inkex.Boolean,
+            default=True,
+            help="direction of rotation",
+        )
+
+    def effect(self):
+        view_center = self.svg.namedview.center
+        rotation = 1 if self.options.rotation else -1
+        whirl = self.options.whirl / 1000
+        for node in self.svg.selection.filter(inkex.PathElement):
+            self.whirl_node(view_center, rotation, whirl, node)
+
+    @staticmethod
+    def whirl_node(center, direction, ammount, node):
+        """Apply a whirl to a path given the center, direction and amount"""
+        path = node.path.to_superpath()
+        for sub in path:
+            for csp in sub:
+                for point in csp:
+                    point[0] -= center[0]
+                    point[1] -= center[1]
+                    dist = math.sqrt((point[0] ** 2) + (point[1] ** 2))
+                    if dist != 0:
+                        art = direction * dist * ammount
+                        theta = math.atan2(point[1], point[0]) + art
+                        point[0] = dist * math.cos(theta)
+                        point[1] = dist * math.sin(theta)
+                    point[0] += center[0]
+                    point[1] += center[1]
+        node.path = path
+
+
+if __name__ == "__main__":
+    Whirl().run()