Fix for stroke rendering instability with stroke geometry shaders.

* Stroke::Resample(int nPoints) was not properly working when a wrong
value was returned from Stroke::getLength2D(), resulting in repeated
warning messages "Warning: incorrect points number" during stroke
rendering.  The main cause was that stroke geometry shaders did not
update the two-dimensional (2D) length (also referred to as curvilinear
abscissa) after they modified the 2D points of stroke vertices.  Now
all stroke geometry shaders make explicit calls for Stroke::UpdateLength()
that has been introduced for recomputing the 2D length.  Many thanks to
Josef who reported the problem together with sample .blend files for
reproducing the issue.

* Missing Python wrapper of Stroke::getLength2D() was added.

1 files changed, 3 insertions, 0 deletions

diff --git a/source/blender/freestyle/intern/stroke/Stroke.h b/source/blender/freestyle/intern/stroke/Stroke.h
index 5e0974edea7..1b1084b54c2 100755
--- a/source/blender/freestyle/intern/stroke/Stroke.h
+++ b/source/blender/freestyle/intern/stroke/Stroke.h
@@ -466,6 +466,9 @@ public:
    */
   void InsertVertex(StrokeVertex *iVertex, StrokeInternal::StrokeVertexIterator next);
 
+  /*! Updates the 2D length of the Stroke */
+  void UpdateLength();
+
   /* Render method */
   void Render(const StrokeRenderer *iRenderer );
   void RenderBasic(const StrokeRenderer *iRenderer );