osg学习（五十六）osg::State的AttributeMap作用

记录当前状态机的所有StateAttribute，比如着色器、视口等。

osg/State
class OSG_EXPORT State : public Referenced
{
        typedef std::pair  AttributePair;
        typedef std::vector                                      AttributeVec;
        struct AttributeStack
        {
            AttributeStack()
            {
                changed = false;
                last_applied_attribute = 0L;
                last_applied_shadercomponent = 0L;
                global_default_attribute = 0L;

            }

            void print(std::ostream& fout) const;

            
            bool                    changed;
            const StateAttribute*   last_applied_attribute;
            const ShaderComponent*  last_applied_shadercomponent;
            ref_ptr global_default_attribute;
            AttributeVec            attributeVec;
        };
        typedef std::map AttributeMap;
}


osg/StateAttribute
class OSG_EXPORT StateAttribute : public Object
{
    typedef std::pair TypeMemberPair;
}