Fix for a failure of SVertex::getFEdge due to a discontinuity of underlying FEdges

introduced by chaining operations.  When two ViewEdges are concatenated by a chaining
operator, the last vertex of one ViewEdge and the first vertex of the other reside
in the same 3D position, so that the latter vertex is omitted.  This caused a pair
of SVertices unconnected by an FEdge.  The present commit intends to fix this issue.

The bug was reported by mato_sus304 with a .blend file reproducing the issue.  Thanks!

1 files changed, 22 insertions, 0 deletions

diff --git a/source/blender/freestyle/intern/stroke/Chain.cpp b/source/blender/freestyle/intern/stroke/Chain.cpp
index 3776cd58a03..dd3c4723cff 100755
--- a/source/blender/freestyle/intern/stroke/Chain.cpp
+++ b/source/blender/freestyle/intern/stroke/Chain.cpp
@@ -49,6 +49,17 @@ void Chain::push_viewedge_back(ViewEdge *iViewEdge, bool orientation)
       ++v;
     else
       --v;
+    // Ensure the continuity of underlying FEdges
+    CurvePoint *cp = _Vertices.back();
+    SVertex *sv_last = cp->B();
+    if (!sv_last) sv_last = cp->A();
+    SVertex *sv_curr = (*v);
+    FEdge *fe = (orientation) ? iViewEdge->fedgeA() : iViewEdge->fedgeB();
+    FEdge *fe2 = fe->duplicate();
+    fe2->setVertexA(sv_last);
+    fe2->setVertexB(sv_curr);
+    sv_last->AddFEdge(fe2);
+    sv_curr->AddFEdge(fe2);
   }
   else
     previous = (*v)->point2d(); 
@@ -99,6 +110,17 @@ void Chain::push_viewedge_front(ViewEdge *iViewEdge, bool orientation)
       ++v;
     else
       --v;
+    // Ensure the continuity of underlying FEdges
+    CurvePoint *cp = _Vertices.front();
+    SVertex *sv_last = cp->A();
+    if (!sv_last) sv_last = cp->B();
+    SVertex *sv_curr = (*v);
+    FEdge *fe = (orientation) ? iViewEdge->fedgeA() : iViewEdge->fedgeB();
+    FEdge *fe2 = fe->duplicate();
+    fe2->setVertexA(sv_curr);
+    fe2->setVertexB(sv_last);
+    sv_last->AddFEdge(fe2);
+    sv_curr->AddFEdge(fe2);
   }
   else
     previous = (*v)->point2d();