Added beginnings of shader composition with the shells of the ShaderComposer and ShaderAttribute classes. This aren't

functional yet, but a useful placeholders for future fucntionality.

include/osg/State

@@ -21,6 +21,7 @@
 #include <osg/BufferObject>
 #include <osg/Observer>
 
+#include <osg/ShaderComposer>
 #include <osg/FrameStamp>
 #include <osg/DisplaySettings>
 #include <osg/Polytope>
@@ -140,6 +141,17 @@ class OSG_EXPORT State : public Referenced, public Observer
         /** Get the current OpenGL context unique ID.*/
         inline unsigned int getContextID() const { return _contextID; }
 
+
+        /** Set the ShaderComposor object that implements shader composition.*/
+        void setShaderComposer(ShaderComposer* sc) { _shaderComposer = sc; }
+
+        /** Get the ShaderComposor object.*/
+        ShaderComposer* getShaderComposer() { return _shaderComposer.get(); }
+
+        /** Get the const ShaderComposor object.*/
+        const ShaderComposer* getShaderComposer() const { return _shaderComposer.get(); }
+
+
         /** Push stateset onto state stack.*/
         void pushStateSet(const StateSet* dstate);
 
@@ -1339,6 +1351,8 @@ class OSG_EXPORT State : public Referenced, public Observer
 
         GraphicsContext*            _graphicsContext;
         unsigned int                _contextID;
+        osg::ref_ptr<ShaderComposer> _shaderComposer;
+
         ref_ptr<FrameStamp>         _frameStamp;
 
         ref_ptr<const RefMatrix>    _identity;