3 files changed, 18 insertions, 15 deletions
diff --git a/src/2geom/d2-sbasis.cpp b/src/2geom/d2-sbasis.cpp
index 7bfb7c6c5..486ada9a2 100644
--- a/src/2geom/d2-sbasis.cpp
+++ b/src/2geom/d2-sbasis.cpp
@@ -185,6 +185,19 @@ split_at_discontinuities (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwsbi
     return ret;
 }
 
+Point unitTangentAt(D2<SBasis> const & a, Coord t, unsigned n)
+{
+    std::vector<Point> derivs = a.valueAndDerivatives(t, n);
+    for (unsigned deriv_n = 1; deriv_n < derivs.size(); deriv_n++) {
+        Coord length = derivs[deriv_n].length();
+        if ( ! are_near(length, 0) ) {
+            // length of derivative is non-zero, so return unit vector
+            return derivs[deriv_n] / length;
+        }
+    }
+    return Point (0,0);
+}
+
 static void set_first_point(Piecewise<D2<SBasis> > &f, Point a){
     if ( f.empty() ){
         f.concat(Piecewise<D2<SBasis> >(D2<SBasis>(Linear(a[X]),Linear(a[Y]))));
diff --git a/src/2geom/d2-sbasis.h b/src/2geom/d2-sbasis.h
index e61067e1b..965ec8746 100644
--- a/src/2geom/d2-sbasis.h
+++ b/src/2geom/d2-sbasis.h
@@ -83,6 +83,11 @@ std::vector<Piecewise<D2<SBasis> > > fuse_nearby_ends(std::vector<Piecewise<D2<S
 
 std::vector<Geom::Piecewise<Geom::D2<Geom::SBasis> > > split_at_discontinuities (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwsbin, double tol = .0001);
 
+/**
+* note that -unitTangentAt(reverse(a),0.) == unitTangentAt(a,1.) but the former is more reliable (sometimes the sign is wrong for the latter)
+*/
+Point unitTangentAt(D2<SBasis> const & a, Coord t, unsigned n = 3);
+
 class CoordIterator
 : public std::iterator<std::input_iterator_tag, SBasis const>
 {
diff --git a/src/live_effects/lpe-powerstroke.cpp b/src/live_effects/lpe-powerstroke.cpp
index 79997ff94..281376cde 100644
--- a/src/live_effects/lpe-powerstroke.cpp
+++ b/src/live_effects/lpe-powerstroke.cpp
@@ -34,21 +34,6 @@
 namespace Geom {
 // should all be moved to 2geom at some point
 
-/**
-* note that -unitTangentAt(reverse(a),0.) == unitTangentAt(a,1.) but the former is more reliable (sometimes the sign is wrong for the latter)
-*/
-Point unitTangentAt( D2<SBasis> const & a, Coord t, unsigned n = 3) {
-    std::vector<Point> derivs = a.valueAndDerivatives(t, n);
-    for (unsigned deriv_n = 1; deriv_n < derivs.size(); deriv_n++) {
-        Coord length = derivs[deriv_n].length();
-        if ( ! are_near(length, 0) ) {
-            // length of derivative is non-zero, so return unit vector
-            return derivs[deriv_n] / length;
-        }
-    }
-    return Point (0,0);
-}
-
 /** Find the point where two straight lines cross.
 */
 boost::optional<Point> intersection_point( Point const & origin_a, Point const & vector_a,