X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=src%2Fline-snapper.cpp;h=219bc7482d7501c54d6259087a488acce0d64d0f;hb=57eb32794c2df43d60ee8f0a9aa8576567358ce6;hp=2fa08e1f1c4880b2430992764ed6895c74989df7;hpb=2b699bb3204f2ac53bf779819aec863903a25960;p=inkscape.git

diff --git a/src/line-snapper.cpp b/src/line-snapper.cpp
index 2fa08e1f1..219bc7482 100644
--- a/src/line-snapper.cpp
+++ b/src/line-snapper.cpp
@@ -28,10 +28,9 @@ void Inkscape::LineSnapper::_doFreeSnap(SnappedConstraints &sc,
                                                     NR::Point const &p,
                                                     bool const &f,
                                                     std::vector<NR::Point> &points_to_snap,
-                                                    std::list<SPItem const *> const &it) const
+                                                    std::list<SPItem const *> const &it,
+                                                    std::vector<NR::Point> *unselected_nodes) const
 {
-    Inkscape::SnappedPoint s = SnappedPoint(p, NR_HUGE);
-
     /* Get the lines that we will try to snap to */
     const LineList lines = _getSnapLines(p);
 
@@ -40,23 +39,13 @@ void Inkscape::LineSnapper::_doFreeSnap(SnappedConstraints &sc,
     for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
         NR::Point const p1 = i->second; // point at guide/grid line
         NR::Point const p2 = p1 + NR::rot90(i->first); // 2nd point at guide/grid line
-        
         // std::cout << "  line through " << i->second << " with normal " << i->first;
+        g_assert(i->first != NR::Point(0,0)); // we cannot project on an linesegment of zero length
         
-        g_assert(i->first != NR::Point(0,0)); // otherwise we'll have div. by zero because NR::L2(d2) = 0
-        
-        // p_proj = projection of p on the grid/guide line running from p1 to p2
-        // p_proj = p1 + u (p2 - p1)
-        // calculate u according to "Minimum Distance between a Point and a Line"
-        // see http://local.wasp.uwa.edu.au/~pbourke/geometry/pointline/        
-        NR::Point const d1(p-p1); // delta 1
-        NR::Point const d2(p2-p1); // delta 1
-        double const u = (d1[NR::X] * d2[NR::X] + d1[NR::Y] * d2[NR::Y]) / (NR::L2(d2) * NR::L2(d2));
-        
-        NR::Point const p_proj(p1 + u*(p2-p1));
+        NR::Point const p_proj = project_on_linesegment(p, p1, p2);
         NR::Coord const dist = NR::L2(p_proj - p);
         //Store any line that's within snapping range
-        if (dist < getDistance()) {
+        if (dist < getSnapperTolerance()) {
             _addSnappedLine(sc, p_proj, dist, i->first, i->second);
             // std::cout << " -> distance = " << dist; 
         }     
@@ -73,33 +62,35 @@ void Inkscape::LineSnapper::_doConstrainedSnap(SnappedConstraints &sc,
                                                std::list<SPItem const *> const &/*it*/) const
 
 {
-    Inkscape::SnappedPoint s = SnappedPoint(p, NR_HUGE);
-
     /* Get the lines that we will try to snap to */
     const LineList lines = _getSnapLines(p);
 
     for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
-
-        /* Normal to the line we're trying to snap along */
-        NR::Point const n(NR::rot90(NR::unit_vector(c.getDirection())));
-
-        NR::Point const point_on_line = c.hasPoint() ? c.getPoint() : p;
-
-        /* Constant term of the line we're trying to snap along */
-        NR::Coord const q0 = dot(n, point_on_line);
-        /* Constant term of the grid or guide line */
-        NR::Coord const q1 = dot(i->first, i->second);        
-
-        /* Try to intersect this line with the target line */
-        Geom::Point t_2geom(NR_HUGE, NR_HUGE);
-        Geom::IntersectorKind const k = Geom::line_intersection(n.to_2geom(), q0, i->first.to_2geom(), q1, t_2geom);
-        NR::Point t(t_2geom);
-
-        if (k == Geom::intersects) {
-            const NR::Coord dist = L2(t - p);
-            //Store any line that's within snapping range
-            if (dist < getDistance()) {
-				_addSnappedLine(sc, t, dist, c.getDirection(), t);
+        if (NR::L2(c.getDirection()) > 0) { // Can't do a constrained snap without a constraint
+            /* Normal to the line we're trying to snap along */
+            NR::Point const n(NR::rot90(NR::unit_vector(c.getDirection())));
+    
+            NR::Point const point_on_line = c.hasPoint() ? c.getPoint() : p;
+    
+            /* Constant term of the line we're trying to snap along */
+            NR::Coord const q0 = dot(n, point_on_line);
+            /* Constant term of the grid or guide line */
+            NR::Coord const q1 = dot(i->first, i->second);        
+    
+            /* Try to intersect this line with the target line */
+            Geom::Point t_2geom(NR_HUGE, NR_HUGE);
+            Geom::IntersectorKind const k = Geom::line_intersection(n.to_2geom(), q0, i->first.to_2geom(), q1, t_2geom);
+            NR::Point t(t_2geom);
+    
+            if (k == Geom::intersects) {
+                const NR::Coord dist = L2(t - p);
+                if (dist < getSnapperTolerance()) {
+    				// When doing a constrained snap, we're already at an intersection.
+                    // This snappoint is therefore fully constrained, so there's no need
+                    // to look for additional intersections; just return the snapped point
+                    // and forget about the line
+                    sc.points.push_back(SnappedPoint(t, dist, getSnapperTolerance(), getSnapperAlwaysSnap())); 
+                }
             }
         }
     }