Added State::s/getRootStateSet() that enables applications to insert a StateSet above all rendering for a graphics context. Utilized in the new shadper pipeline functionality

include/osg/State

@@ -806,6 +806,12 @@ class OSG_EXPORT State : public Referenced
         inline const DisplaySettings* getDisplaySettings() const { return _displaySettings.get(); }
 
 
+        /** Set the root StateSet this is applied above all StateSet that are pushed and popped during the draw traversal.*/
+        void setRootStateSet(osg::StateSet* stateset);
+
+        /** Get the root StateSet.*/
+        osg::StateSet* getRootStateSet() { return _rootStateSet.get(); }
+
 
         /** Set flag for early termination of the draw traversal.*/
         void setAbortRenderingPtr(bool* abortPtr) { _abortRenderingPtr = abortPtr; }
@@ -1047,6 +1053,8 @@ class OSG_EXPORT State : public Referenced
         GraphicsContext*            _graphicsContext;
         unsigned int                _contextID;
 
+        osg::ref_ptr<osg::StateSet>     _rootStateSet;
+
         osg::ref_ptr<VertexArrayState>  _globalVertexArrayState;
         VertexArrayState*               _vas;
 

src/osg/State.cpp

@@ -507,9 +507,36 @@ void State::setMaxBufferObjectPoolSize(unsigned int size)
     OSG_INFO<<"osg::State::_maxBufferObjectPoolSize="<<_maxBufferObjectPoolSize<<std::endl;
 }
 
+void State::setRootStateSet(osg::StateSet* stateset)
+{
+    if (_rootStateSet == stateset) return;
+
+    _rootStateSet = stateset;
+
+    if (_stateStateStack.empty())
+    {
+        if (stateset) pushStateSet(stateset);
+    }
+    else
+    {
+        StateSetStack previousStateSetStack = _stateStateStack;
+
+        // we want to reset all the various state stacks, inserting the new root StateSet as the topmost one automatically (popeAllStateSet() does this.)
+        popAllStateSets();
+
+        // now we have to add back in all the StateSet's to make sure the state is consistent
+        for(StateSetStack::iterator itr = previousStateSetStack.begin();
+            itr != previousStateSetStack.end();
+            ++itr)
+        {
+            pushStateSet(*itr);
+        }
+    }
+}
+
+
 void State::pushStateSet(const StateSet* dstate)
 {
-
     _stateStateStack.push_back(dstate);
     if (dstate)
     {
@@ -551,6 +578,8 @@ void State::popAllStateSets()
     applyModelViewMatrix(0);
 
     _lastAppliedProgramObject = 0;
+
+    if (_rootStateSet.valid()) pushStateSet(_rootStateSet.get());
 }
 
 void State::popStateSet()
@@ -678,7 +707,7 @@ void State::captureCurrentState(StateSet& stateset) const
 
 void State::apply(const StateSet* dstate)
 {
-    // OSG_NOTICE<<__PRETTY_FUNCTION__<<std::endl;
+    // OSG_NOTICE<<__PRETTY_FUNCTION__<<" _stateStateStack.size()="<<_stateStateStack.size()<<std::endl;
 
     if (_checkGLErrors==ONCE_PER_ATTRIBUTE) checkGLErrors("start of State::apply(StateSet*)");
 
@@ -774,7 +803,7 @@ void State::apply(const StateSet* dstate)
 
 void State::apply()
 {
-    // OSG_NOTICE<<__PRETTY_FUNCTION__<<std::endl;
+    // OSG_NOTICE<<__PRETTY_FUNCTION__<<" _stateStateStack.size()="<<_stateStateStack.size()<<std::endl;
 
 
     if (_checkGLErrors==ONCE_PER_ATTRIBUTE) checkGLErrors("start of State::apply()");