Introduced CMake option OSG_PROVIDE_READFILE option that defaults to ON, but when switched to OFF disables the building of the osgDB::read*File() methods,

forcing users to use osgDB::readRef*File() methods.  The later is preferable as it closes a potential threading bug when using paging databases in conjunction
with the osgDB::Registry Object Cache.  This threading bug occurs when one thread gets an object from the Cache via an osgDB::read*File() call where only
a pointer to the object is passed back, so taking a reference to the object is delayed till it gets reassigned to a ref_ptr<>, but at the same time another
thread calls a flush of the Object Cache deleting this object as it's referenceCount is now zero.  Using osgDB::readREf*File() makes sure the a ref_ptr<> is
passed back and the referenceCount never goes to zero.

To ensure the OSG builds when OSG_PROVIDE_READFILE is to OFF the many cases of osgDB::read*File() usage had to be replaced with a ref_ptr<> osgDB::readRef*File()
usage.  The avoid this change causing lots of other client code to be rewritten to handle the use of ref_ptr<> in place of C pointer I introduced a serious of
templte methods in various class to adapt ref_ptr<> to the underly C pointer to be passed to old OSG API's, example of this is found in include/osg/Group:

    bool addChild(Node* child); // old method which can only be used with a Node*

    tempalte<class T> bool addChild(const osg::ref_ptr<T>& child) { return addChild(child.get()); } // adapter template method

These changes together cover 149 modified files, so it's a large submission. This extent of changes are warrent to make use of the Object Cache
and multi-threaded loaded more robust.



git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/branches/OpenSceneGraph-3.4@15165 16af8721-9629-0410-8352-f15c8da7e697

include/osgTerrain/Layer

@@ -60,6 +60,9 @@ class OSGTERRAIN_EXPORT Layer : public osg::Object
         std::string getCompoundName() const { return createCompoundSetNameAndFileName(getName(), getFileName()); }
 
         void setLocator(Locator* locator) { _locator = locator; }
+
+        template<class T> void setLocator(const osg::ref_ptr<T>& locator) { setLocator(locator.get()); }
+
         Locator* getLocator() { return _locator.get(); }
         const Locator* getLocator() const { return _locator.get(); }
 
@@ -314,6 +317,8 @@ class OSGTERRAIN_EXPORT ImageLayer : public Layer
 
         void setImage(osg::Image* image);
 
+        template<class T> void setImage(const osg::ref_ptr<T>& image) { return setImage(image.get()); }
+
         /** Return image associated with layer. */
         virtual osg::Image* getImage() { return _image.get(); }
 
@@ -354,6 +359,9 @@ class OSGTERRAIN_EXPORT ContourLayer : public Layer
         virtual bool transform(float offset, float scale);
 
         void setTransferFunction(osg::TransferFunction1D* tf);
+
+        template<class T> void setTransferFunction(const osg::ref_ptr<T>& tf) { return setTransferFunction(tf.get()); }
+
         osg::TransferFunction1D* getTransferFunction() { return _tf.get(); }
         const osg::TransferFunction1D* getTransferFunction() const { return _tf.get(); }
 
@@ -401,6 +409,9 @@ class OSGTERRAIN_EXPORT HeightFieldLayer : public Layer
         virtual bool transform(float offset, float scale);
 
         void setHeightField(osg::HeightField* hf);
+
+        template<class T> void setHeightField(const osg::ref_ptr<T>& hf) { return setHeightField(hf.get()); }
+
         osg::HeightField* getHeightField() { return _heightField.get(); }
         const osg::HeightField* getHeightField() const { return _heightField.get(); }
 
@@ -516,14 +527,21 @@ class OSGTERRAIN_EXPORT CompositeLayer : public Layer
 
 
         void setLayer(unsigned int i, Layer* layer) { if (i>=_layers.size()) _layers.resize(i+1); _layers[i].layer = layer; }
+
+        template<class T> void setLayer(unsigned int i, const osg::ref_ptr<T>& layer) { setLayer(i, layer.get()); }
+
         Layer* getLayer(unsigned int i) { return i<_layers.size() ? _layers[i].layer.get() : 0; }
+
         const Layer* getLayer(unsigned int i) const { return i<_layers.size() ? _layers[i].layer.get() : 0; }
 
         void addLayer(const std::string& compoundname);
+
         void addLayer(const std::string& setname, const std::string& filename);
 
         void addLayer(Layer* layer) { _layers.push_back(CompoundNameLayer(layer->getName(),layer->getFileName(),layer)); }
 
+        template<class T> void addLayer(const osg::ref_ptr<T>& layer) { return addLayer(layer.get()); }
+
         void removeLayer(unsigned int i) { _layers.erase(_layers.begin()+i); }
 
         unsigned int getNumLayers() const { return static_cast<unsigned int>(_layers.size()); }

include/osgTerrain/TerrainTile

@@ -102,6 +102,8 @@ class OSGTERRAIN_EXPORT TerrainTile : public osg::Group
         /** Set the TerrainTechnique*/
         void setTerrainTechnique(TerrainTechnique* terrainTechnique);
 
+        template<class T> void setTerrainTechnique(const osg::ref_ptr<T>& terrainTechnique) { setTerrainTechnique(terrainTechnique.get()); }
+
         /** Get the TerrainTechnique*/
         TerrainTechnique* getTerrainTechnique() { return _terrainTechnique.get(); }
 
@@ -113,6 +115,8 @@ class OSGTERRAIN_EXPORT TerrainTile : public osg::Group
           * The locator takes non-dimensional s,t coordinates into the X,Y,Z world coords and back.*/
         void setLocator(Locator* locator) { _locator = locator; }
 
+        template<class T> void setLocator(const osg::ref_ptr<T>& locator) { setLocator(locator.get()); }
+
         /** Get the coordinate frame locator of the terrain node.*/
         Locator* getLocator() { return _locator.get(); }
 
@@ -122,6 +126,8 @@ class OSGTERRAIN_EXPORT TerrainTile : public osg::Group
         /** Set the layer to use to define the elevations of the terrain.*/
         void setElevationLayer(Layer* layer);
 
+        template<class T> void setElevationLayer(const osg::ref_ptr<T>& layer) { setElevationLayer(layer.get()); }
+
         /** Get the layer to use to define the elevations of the terrain.*/
         Layer* getElevationLayer() { return _elevationLayer.get(); }
 
@@ -132,6 +138,8 @@ class OSGTERRAIN_EXPORT TerrainTile : public osg::Group
         /** Set a color layer with specified layer number.*/
         void setColorLayer(unsigned int i, Layer* layer);
 
+        template<class T> void setColorLayer(unsigned int i, const osg::ref_ptr<T>& layer) { setColorLayer(i, layer.get()); }
+
         /** Get color layer with specified layer number.*/
         Layer* getColorLayer(unsigned int i) { return i<_colorLayers.size() ? _colorLayers[i].get() : 0; }
 
@@ -139,7 +147,7 @@ class OSGTERRAIN_EXPORT TerrainTile : public osg::Group
         const Layer* getColorLayer(unsigned int i) const { return i<_colorLayers.size() ? _colorLayers[i].get() : 0; }
 
         /** Get the number of colour layers.*/
-        unsigned int getNumColorLayers() const { return static_cast<unsigned int>(_colorLayers.size()); }
+        unsigned int getNumColorLayers() const { return _colorLayers.size(); }
 
 
         /** Set hint to whether the TerrainTechnique should create per vertex normals for lighting purposes.*/