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, 23 insertions, 7 deletions

diff --git a/source/blender/freestyle/intern/stroke/Operators.cpp b/source/blender/freestyle/intern/stroke/Operators.cpp
index ef1b2662998..ea996c67785 100755
--- a/source/blender/freestyle/intern/stroke/Operators.cpp
+++ b/source/blender/freestyle/intern/stroke/Operators.cpp
@@ -938,10 +938,18 @@ Stroke* createStroke(Interface1D& inter) {
       stroke_vertex = new StrokeVertex(cp);
     current = stroke_vertex->point2d();
     Vec3r vec_tmp(current - previous);
-    currentCurvilignAbscissa += vec_tmp.norm();
-    stroke_vertex->setCurvilinearAbscissa(currentCurvilignAbscissa);
-    stroke->push_back(stroke_vertex);
-    previous = current;
+    real vec_tmp_norm = vec_tmp.norm();
+    if((stroke->strokeVerticesSize() > 0) && (vec_tmp_norm < 1.e-06)){
+      // The point we just created is superimposed with the 
+      // previous one. We remove it to avoid having to deal
+      // with this kind of singularities in the strip creation
+      delete stroke_vertex;
+    }else{
+      currentCurvilignAbscissa += vec_tmp.norm();
+      stroke_vertex->setCurvilinearAbscissa(currentCurvilignAbscissa);
+      stroke->push_back(stroke_vertex);
+      previous = current;
+    }
     ++it;
   } while((it != itend) && (it != itfirst));
 
@@ -959,9 +967,17 @@ Stroke* createStroke(Interface1D& inter) {
       stroke_vertex = new StrokeVertex(cp);
     current = stroke_vertex->point2d();
     Vec3r vec_tmp(current - previous);
-    currentCurvilignAbscissa += vec_tmp.norm();
-    stroke_vertex->setCurvilinearAbscissa(currentCurvilignAbscissa);
-    stroke->push_back(stroke_vertex);
+    real vec_tmp_norm = vec_tmp.norm();
+    if((stroke->strokeVerticesSize() > 0) && (vec_tmp_norm < 1.e-06)){
+      // The point we just created is superimposed with the 
+      // previous one. We remove it to avoid having to deal
+      // with this kind of singularities in the strip creation
+      delete stroke_vertex;
+    }else{
+      currentCurvilignAbscissa += vec_tmp.norm();
+      stroke_vertex->setCurvilinearAbscissa(currentCurvilignAbscissa);
+      stroke->push_back(stroke_vertex);
+    }
   }
   stroke->setLength(currentCurvilignAbscissa);
   return stroke;