powerstroke: work on cusps, so people can play with it a bit. it is not done yet ! so may change in future...

(partial update to latest 2geom, for reflection transform)

(bzr r11024)

2 files changed, 19 insertions, 3 deletions

diff --git a/src/2geom/transforms.cpp b/src/2geom/transforms.cpp
index b8355cadc..65df9b22f 100644
--- a/src/2geom/transforms.cpp
+++ b/src/2geom/transforms.cpp
@@ -5,8 +5,9 @@
  * Authors:
  *   ? <?@?.?>
  *   Krzysztof Kosiński <tweenk.pl@gmail.com>
+ *   Johan Engelen
  * 
- * Copyright ?-2009 Authors
+ * Copyright ?-2012 Authors
  *
  * This library is free software; you can redistribute it and/or
  * modify it either under the terms of the GNU Lesser General Public
@@ -171,8 +172,16 @@ void check_transforms()
     m = z * t; m = z * s; m = z * r; m = z * h; m = z * v; m = z * z;
 }
 
+Affine reflection(Point const & vector, Point const & origin) {
+    Geom::Point vec_norm = unit_vector(vector);
+    Affine mirror ( vec_norm[X]*vec_norm[X] - vec_norm[Y]*vec_norm[Y], 2 * vec_norm[X] * vec_norm[Y] ,
+                    2 * vec_norm[X] * vec_norm[Y], vec_norm[Y]*vec_norm[Y] - vec_norm[X]*vec_norm[X] ,
+                    0 ,0 );
+    return Translate(-origin) * mirror * Translate(origin);
 }
 
+} // namespace Geom
+
 /*
   Local Variables:
   mode:c++
diff --git a/src/2geom/transforms.h b/src/2geom/transforms.h
index eaf869056..869e955c7 100644
--- a/src/2geom/transforms.h
+++ b/src/2geom/transforms.h
@@ -5,8 +5,9 @@
  * Authors:
  *   ? <?@?.?>
  *   Krzysztof Kosiński <tweenk.pl@gmail.com>
+ *   Johan Engelen
  * 
- * Copyright ?-2009 Authors
+ * Copyright ?-2012 Authors
  *
  * This library is free software; you can redistribute it and/or
  * modify it either under the terms of the GNU Lesser General Public
@@ -280,7 +281,7 @@ inline bool are_near(VShear const &a, VShear const &b, Coord eps=EPSILON) {
  * The translation part is applied first, then the result is scaled from the new origin.
  * This way when the class is used to accumulate a zoom transform, trans always points
  * to the new origin in original coordinates.
- * @ingroup Transform */
+ * @ingroup Transforms */
 class Zoom
     : public TransformOperations< Zoom >
 {
@@ -338,6 +339,12 @@ inline Translate pow(Translate const &t, int n) {
     return ret;
 }
 
+
+/** @brief Reflects objects about line.
+ * The line, defined by a vector along the line and a point on it, acts as a mirror.
+ */
+Affine reflection(Point const & vector, Point const & origin);
+
 //TODO: decomposition of Affine into some finite combination of the above classes
 
 } // end namespace Geom