Began work on providing support for threading camera cull traversals in parallel with

the previous frames draw traversal.  Changes range from osg::State, through osgUtil::RenderBin, through to osgViewer

include/osgViewer/View

@@ -25,6 +25,30 @@
 
 namespace osgViewer {
 
+class OSGVIEWER_EXPORT EndOfDynamicDrawBlock : public osg::State::DynamicObjectRenderingCompletedCallback
+{
+    public:
+    
+        EndOfDynamicDrawBlock();
+    
+        void completed(osg::State* state);
+
+        void block();
+
+        void release();
+
+        void set(unsigned int blockCount);
+
+    protected:
+
+        ~EndOfDynamicDrawBlock();
+
+        OpenThreads::Mutex _mut;
+        OpenThreads::Condition _cond;
+        unsigned int _blockCount;
+};
+
+
 /** View holds a single view on a scene, this view may be composed of one or more slave cameras.*/
 class OSGVIEWER_EXPORT View : public osg::View, public osgGA::GUIActionAdapter
 {

include/osgViewer/Viewer

@@ -63,6 +63,13 @@ class OSGVIEWER_EXPORT Viewer : public osgViewer::View
         /** Get the threading model the rendering traversals will use.*/
         ThreadingModel getThreadingModel() const { return _threadingModel; }
 
+        /** Set whether the main thread, calling frame(), should be used for the rendering traversals.*/
+        void setUseMainThreadForRenderingTraversals(bool flag);
+        
+        /** Get whether the main thread, calling frame(), should be used for the rendering traversals.*/
+        bool getUseMainThreadForRenderingTraversals() const { return _useMainThreadForRenderingTraversal; }
+
+
         enum BarrierPosition
         {
             BeforeSwapBuffers,
@@ -148,11 +155,13 @@ class OSGVIEWER_EXPORT Viewer : public osgViewer::View
         int _keyEventSetsDone;
         bool _quitEventSetsDone;
         
-        ThreadingModel _threadingModel;
+        ThreadingModel  _threadingModel;
+        bool            _useMainThreadForRenderingTraversal;
         BarrierPosition _endBarrierPosition;
 
         osg::ref_ptr<osg::BarrierOperation> _startRenderingBarrier;
         osg::ref_ptr<osg::BarrierOperation> _endRenderingDispatchBarrier;
+        osg::ref_ptr<EndOfDynamicDrawBlock> _endDynamicDrawBlock;
 
         unsigned int computeNumberOfThreadsIncludingMainRequired();