make mGrid (and friends) private again, create accessor method to return bool of mGrid.empty()

components/terrain/quadtreeworld.cpp

@@ -442,7 +442,7 @@ void QuadTreeWorld::accept(osg::NodeVisitor &nv)
     }
 
     if (isCullVisitor)
-        updateWaterCullingView(mHeightCullCallback, vd, static_cast<osgUtil::CullVisitor*>(&nv), mStorage->getCellWorldSize(), !mGrid.empty());
+        updateWaterCullingView(mHeightCullCallback, vd, static_cast<osgUtil::CullVisitor*>(&nv), mStorage->getCellWorldSize(), !isGridEmpty());
 
     if (!isCullVisitor)
         vd->clear(); // we can't reuse intersection views in the next frame because they only contain what is touched by the intersection ray.

components/terrain/terraingrid.hpp

@@ -28,6 +28,9 @@ namespace Terrain
         View* createView();
 
     protected:
+        bool isGridEmpty() { return mGrid.empty(); }
+
+    private:
         osg::ref_ptr<osg::Node> buildTerrain (osg::Group* parent, float chunkSize, const osg::Vec2f& chunkCenter);
         void updateWaterCulling();