Bug fixes from Stéphane Grabli, one of the coauthors of the

original Freestyle:

* Fix for making the stroke construction more robust to nearly
overlapping vertices.

* Fix for a bug in the computation of the occluded surfaces.

These changes make the visibility computation more robust and
the line quality generally higher.

1 files changed, 8 insertions, 1 deletions

diff --git a/source/blender/freestyle/intern/stroke/StrokeRep.cpp b/source/blender/freestyle/intern/stroke/StrokeRep.cpp
index fbe1273bac0..6ae15c71833 100755
--- a/source/blender/freestyle/intern/stroke/StrokeRep.cpp
+++ b/source/blender/freestyle/intern/stroke/StrokeRep.cpp
@@ -254,7 +254,14 @@ Strip::createStrip (const vector<StrokeVertex*>& iStrokeVertices)
       else 
         _vertices.push_back(new StrokeVertexRep(p-thickness[0]*stripDir));
       ++i;
-		
+
+      if((stripDir+stripDirPrev).norm() <= 1.e-06){
+        // the strip is most likely doing a U-turn, we can't compute the average vector.
+        // We just continue and hope it's ok
+        vPrev = v;
+        continue;
+      }
+      
       // if the angle is obtuse, we simply average the directions to avoid the singularity
       stripDir=stripDir+stripDirPrev;
       if ((dirNorm<ZERO) || (dirPrevNorm<ZERO) || (stripDir.norm() < ZERO)) {