Enable tangential and perpendicular snapping to paths (in the node-tool, pen-tool, pencil-tool, and for guide manipulation; cannot be toggled yet, will always be active when snapping to paths)

(bzr r10886)

2 files changed, 19 insertions, 0 deletions

diff --git a/src/2geom/sbasis-geometric.cpp b/src/2geom/sbasis-geometric.cpp
index 017b377c9..0987953de 100644
--- a/src/2geom/sbasis-geometric.cpp
+++ b/src/2geom/sbasis-geometric.cpp
@@ -764,6 +764,23 @@ std::vector<double> find_normals(Point P, D2<SBasis> const &A) {
     return roots(crs);
 }
 
+/**
+* \brief returns all the parameter values of A whose normal is parallel to vector V.
+* \relates D2
+*/
+std::vector<double> find_normals_by_vector(Point V, D2<SBasis> const &A) {
+    SBasis crs = dot(derivative(A), V);
+    return roots(crs);
+}
+/**
+* \brief returns all the parameter values of A whose tangent is parallel to vector V.
+* \relates D2
+*/
+std::vector<double> find_tangents_by_vector(Point V, D2<SBasis> const &A) {
+    SBasis crs = dot(derivative(A), rot90(V));
+    return roots(crs);
+}
+
 }
 //}; // namespace
 
diff --git a/src/2geom/sbasis-geometric.h b/src/2geom/sbasis-geometric.h
index 00b64b430..43c624fb4 100644
--- a/src/2geom/sbasis-geometric.h
+++ b/src/2geom/sbasis-geometric.h
@@ -101,7 +101,9 @@ cubics_with_prescribed_curvature(Point const &M0,   Point const &M1,
 
 
 std::vector<double> find_tangents(Point P, D2<SBasis> const &A);
+std::vector<double> find_tangents_by_vector(Point V, D2<SBasis> const &A);
 std::vector<double> find_normals(Point P, D2<SBasis> const &A);
+std::vector<double> find_normals_by_vector(Point V, D2<SBasis> const &A);
 
 };