gls_render_view_change_manager.h

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/*! \file
  \brief RenderViewChangeManager to smooth updating of the render view

  \par Copyright Information

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*/

#ifndef GLS_RENDER_VIEW_CHANGE_MANAGER_H
#define GLS_RENDER_VIEW_CHANGE_MANAGER_H

#include "gls_include.h"
#include "dynamic_array.h"
#include "gls_matrix.h"

namespace disti
{
    /** Interface for listeners that need to perform specific actions once per frame for each "camera" rendering a view. */
    class GlsRenderViewChangeListener
    {
    public:
        /** Called whenever a new view has been applied to OpenGL.
          * \param modelViewMatrix the matrix of the new view
          */
        GLS_EXPORT virtual void OnViewChanged(const GlsMatrixType& modelViewMatrix) = 0;
    protected:
        /** Protected, non-virtual destructor -- no polymorphic deletion */
        ~GlsRenderViewChangeListener() {}
    };

    /** Singleton to keep a list of all listeners for changes in the render view. */
    class GlsRenderViewChangeManager
    {
    public:
        /** Add a listener to the notification list for render views changing
          * Note: Does not take ownership of the listener
          * \param listener the listener to add
          */
        GLS_EXPORT static void AddRenderViewChangeListener(GlsRenderViewChangeListener* listener)
        {
            GetListeners().PushObject(listener);
        }
        
        /** Remove a listener from the notification list for render views changing
          * \param listener the listener to remove
          */
        GLS_EXPORT static void RemoveRenderViewChangeListener(GlsRenderViewChangeListener* listener)
        {
            GetListeners().DeleteObject(listener);
        }
        
        /** Notify all listeners that a new view has been applied to OpenGL
          * \param modelViewMatrix the matrix of the new view
          */
        GLS_EXPORT static void NotifyRenderViewChanged(const GlsMatrixType& modelViewMatrix)
        {
            Listeners& listeners = GetListeners();
            for( unsigned int i = 0; i < listeners.Count(); ++i )
            {
                listeners[i]->OnViewChanged(modelViewMatrix);
            }
        }
    private:
        // Member types
        typedef DynamicArray<GlsRenderViewChangeListener*> Listeners;

        // Disable construction for static class
        GlsRenderViewChangeManager(); // = delete

        static Listeners& GetListeners()
        {
            static Listeners s_renderViewChangeListeners;
            return s_renderViewChangeListeners;
        }
    };

} // namespace disti

#endif