1 files changed, 117 insertions, 0 deletions
diff --git a/share/extensions/motion.py b/share/extensions/motion.py
new file mode 100755
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--- /dev/null
+++ b/share/extensions/motion.py
@@ -0,0 +1,117 @@
+#!/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.
+#
+
+import math
+
+import inkex
+from inkex.paths import Move, Line, Curve, ZoneClose, Arc, Path, Vert, Horz, TepidQuadratic, Quadratic, Smooth
+from inkex.transforms import Vector2d
+from inkex.bezier import beziertatslope, beziersplitatt
+
+
+class Motion(inkex.EffectExtension):
+    """Generate a motion path"""
+
+    def add_arguments(self, pars):
+        pars.add_argument("-a", "--angle", type=float, default=45.0, \
+                          help="direction of the motion vector")
+        pars.add_argument("-m", "--magnitude", type=float, default=100.0, \
+                          help="magnitude of the motion vector")
+
+    @staticmethod
+    def makeface(last, segment, facegroup, delx, dely):
+        """translate path segment along vector"""
+        elem = facegroup.add(inkex.PathElement())
+
+        npt = segment.translate([delx, dely])
+
+        # reverse direction of path segment
+        if isinstance(segment, Curve):
+            rev = Curve(npt.x3, npt.y3, npt.x2, npt.y2,
+                        last[0] + delx, last[1] + dely
+                        )
+        elif isinstance(segment, Line):
+            rev = Line(last[0] + delx, last[1] + dely)
+        else:
+            raise RuntimeError("Unexpected segment type {}".format(type(segment)))
+
+        elem.path = inkex.Path([
+            Move(last[0], last[1]),
+            segment,
+            npt.to_line(Vector2d()),
+            rev,
+            ZoneClose(),
+        ])
+
+    def effect(self):
+        delx = math.cos(math.radians(self.options.angle)) * self.options.magnitude
+        dely = math.sin(math.radians(self.options.angle)) * self.options.magnitude
+        for node in self.svg.selection.filter(inkex.PathElement).values():
+            group = node.getparent().add(inkex.Group())
+            facegroup = group.add(inkex.Group())
+            group.append(node)
+
+            if node.transform:
+                group.transform = node.transform
+                node.transform = None
+
+            facegroup.style = node.style
+
+            for cmd_proxy in node.path.to_absolute().proxy_iterator():
+                self.process_segment(cmd_proxy, facegroup, delx, dely)
+
+    @staticmethod
+    def process_segment(cmd_proxy, facegroup, delx, dely):
+        """Process each segments"""
+
+        segments = []
+        if isinstance(cmd_proxy.command, (Curve, Smooth, TepidQuadratic, Quadratic, Arc)):
+            prev = cmd_proxy.previous_end_point
+            for curve in cmd_proxy.to_curves():
+                bez = [prev] + curve.to_bez()
+                prev = curve.end_point(cmd_proxy.first_point, prev)
+                tees = [t for t in beziertatslope(bez, (dely, delx)) if 0 < t < 1]
+                tees.sort()
+                if len(tees) == 1:
+                    one, two = beziersplitatt(bez, tees[0])
+                    segments.append(Curve(*(one[1] + one[2] + one[3])))
+                    segments.append(Curve(*(two[1] + two[2] + two[3])))
+                elif len(tees) == 2:
+                    one, two = beziersplitatt(bez, tees[0])
+                    two, three = beziersplitatt(two, tees[1])
+                    segments.append(Curve(*(one[1] + one[2] + one[3])))
+                    segments.append(Curve(*(two[1] + two[2] + two[3])))
+                    segments.append(Curve(*(three[1] + three[2] + three[3])))
+                else:
+                    segments.append(curve)
+        elif isinstance(cmd_proxy.command, (Line, Curve)):
+            segments.append(cmd_proxy.command)
+        elif isinstance(cmd_proxy.command, ZoneClose):
+            segments.append(Line(cmd_proxy.first_point.x, cmd_proxy.first_point.y))
+        elif isinstance(cmd_proxy.command, (Vert, Horz)):
+            segments.append(cmd_proxy.command.to_line(cmd_proxy.end_point))
+
+        for seg in Path([Move(*cmd_proxy.previous_end_point)] + segments).proxy_iterator():
+            if isinstance(seg.command, Move): continue
+            Motion.makeface(seg.previous_end_point, seg.command, facegroup, delx, dely)
+
+
+if __name__ == '__main__':
+    Motion().run()