Freestyle: Partial fix for thinning strokes due to flipping stroke directions at TVertices.

A description of the problem is found in https://developer.blender.org/T36425#19 .

The cause of the issue was identified as roudning errors in Operators::createStroke() due
to insufficient numerical precision.  Precision promotion from float to double was done in
the return values of getPoint3D/2D methods in Interface0D and its subclasses in C++
(data members stored in the 0D classes have already been in double precision).

3 files changed, 22 insertions, 21 deletions

diff --git a/source/blender/freestyle/intern/stroke/Curve.h b/source/blender/freestyle/intern/stroke/Curve.h
index 17b9a5c0a1f..6b799c921a4 100644
--- a/source/blender/freestyle/intern/stroke/Curve.h
+++ b/source/blender/freestyle/intern/stroke/Curve.h
@@ -95,7 +95,7 @@ public: // Implementation of Interface0D
 	}
 
 	/*!  Returns the 3D point. */ 
-	virtual Vec3f getPoint3D() const
+	virtual Vec3r getPoint3D() const
 	{
 		return _Point3d;
 	}
@@ -119,9 +119,9 @@ public: // Implementation of Interface0D
 	}
 
 	/*!  Returns the 2D point. */ 
-	virtual Vec2f getPoint2D() const
+	virtual Vec2r getPoint2D() const
 	{
-		return Vec2f((float)_Point2d.x(), (float)_Point2d.y());
+		return Vec2r(_Point2d.x(), _Point2d.y());
 	}
 
 	virtual FEdge *getFEdge(Interface0D& inter);
diff --git a/source/blender/freestyle/intern/stroke/Operators.cpp b/source/blender/freestyle/intern/stroke/Operators.cpp
index 2e68aa0c1fa..2f05413fcbe 100644
--- a/source/blender/freestyle/intern/stroke/Operators.cpp
+++ b/source/blender/freestyle/intern/stroke/Operators.cpp
@@ -32,6 +32,7 @@
 #include "Operators.h"
 #include "Canvas.h"
 #include "Stroke.h"
+#include "StrokeIterators.h"
 #include "CurveIterators.h"
 
 #include "BKE_global.h"
@@ -1092,20 +1093,20 @@ static Stroke *createStroke(Interface1D& inter)
 	if (hasSingularity) {
 		// Try to address singular points such that the distance between two subsequent vertices
 		// are smaller than epsilon.
-		Interface0DIterator v = stroke->verticesBegin();
-		Interface0DIterator vnext = v;
+		StrokeInternal::StrokeVertexIterator v = stroke->strokeVerticesBegin();
+		StrokeInternal::StrokeVertexIterator vnext = v;
 		++vnext;
-		Vec2r next((*v).getPoint2D());
+		Vec2r next((*v).getPoint());
 		while (!vnext.isEnd()) {
 			current = next;
-			next = (*vnext).getPoint2D();
+			next = (*vnext).getPoint();
 			if ((next - current).norm() < 1.0e-6) {
-				Interface0DIterator vprevious = v;
+				StrokeInternal::StrokeVertexIterator vprevious = v;
 				if (!vprevious.isBegin())
 					--vprevious;
 
 				// collect a set of overlapping vertices
-				std::vector<Interface0D *> overlapping_vertices;
+				std::vector<StrokeVertex *> overlapping_vertices;
 				overlapping_vertices.push_back(&(*v));
 				do {
 					overlapping_vertices.push_back(&(*vnext));
@@ -1114,17 +1115,17 @@ static Stroke *createStroke(Interface1D& inter)
 					++vnext;
 					if (vnext.isEnd())
 						break;
-					next = (*vnext).getPoint2D();
+					next = (*vnext).getPoint();
 				} while ((next - current).norm() < 1.0e-6);
 
 				Vec2r target;
 				bool reverse;
 				if (!vnext.isEnd()) {
-					target = (*vnext).getPoint2D();
+					target = (*vnext).getPoint();
 					reverse = false;
 				}
 				else if (!vprevious.isBegin()) {
-					target = (*vprevious).getPoint2D();
+					target = (*vprevious).getPoint();
 					reverse = true;
 				}
 				else {
@@ -1132,7 +1133,7 @@ static Stroke *createStroke(Interface1D& inter)
 					delete stroke;
 					return NULL;
 				}
-				current = overlapping_vertices.front()->getPoint2D();
+				current = overlapping_vertices.front()->getPoint();
 				Vec2r dir(target - current);
 				real dist = dir.norm();
 				real len = 1.0e-3; // default offset length
@@ -1144,10 +1145,10 @@ static Stroke *createStroke(Interface1D& inter)
 				Vec2r offset(dir * len);
 				// add the offset to the overlapping vertices
 				StrokeVertex *sv;
-				std::vector<Interface0D *>::iterator it = overlapping_vertices.begin();
+				std::vector<StrokeVertex *>::iterator it = overlapping_vertices.begin();
 				if (!reverse) {
 					for (int n = 1; n < nvert; n++) {
-						sv = dynamic_cast<StrokeVertex*>(*it);
+						sv = (*it);
 						sv->setPoint(sv->getPoint() + offset * n);
 						++it;
 					}
@@ -1155,7 +1156,7 @@ static Stroke *createStroke(Interface1D& inter)
 				else {
 					int last = nvert - 1;
 					for (int n = 0; n < last; n++) {
-						sv = dynamic_cast<StrokeVertex*>(*it);
+						sv = (*it);
 						sv->setPoint(sv->getPoint() + offset * (last - n));
 						++it;
 					}
diff --git a/source/blender/freestyle/intern/stroke/Stroke.h b/source/blender/freestyle/intern/stroke/Stroke.h
index f6451d8e487..5e6c2fcf6cb 100644
--- a/source/blender/freestyle/intern/stroke/Stroke.h
+++ b/source/blender/freestyle/intern/stroke/Stroke.h
@@ -375,14 +375,14 @@ public:
 		return _Point2d[1];
 	}
 
-	/*! Returns the 2D point coordinates as a Vec2d */
-	Vec2f getPoint ()
+	/*! Returns the 2D point coordinates as a Vec2r */
+	inline Vec2r getPoint() const
 	{
-		return Vec2f((float)point2d()[0], (float)point2d()[1]);
+		return getPoint2D();
 	}
 
 	/*! Returns the ith 2D point coordinate (i=0 or 1)*/
-	inline real  operator[](const int i) const
+	inline real operator[](const int i) const
 	{
 		return _Point2d[i];
 	}
@@ -438,7 +438,7 @@ public:
 	}
 
 	/*! sets the 2D x and y values */
-	inline void setPoint(const Vec2f& p)
+	inline void setPoint(const Vec2r& p)
 	{
 		_Point2d[0] = p[0];
 		_Point2d[1] = p[1];