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  ** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
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  #ifndef QT3DRENDER_RENDER_RENDERSTATE_H
  #define QT3DRENDER_RENDER_RENDERSTATE_H
  
  //
  //  W A R N I N G
  //  -------------
  //
  // This file is not part of the Qt API.  It exists for the convenience
  // of other Qt classes.  This header file may change from version to
  // version without notice, or even be removed.
  //
  // We mean it.
  //
  
  #include <Qt3DRender/private/genericstate_p.h>
  #include <Qt3DRender/private/renderstates_p.h>
  #include <Qt3DRender/private/statevariant_p.h>
  #include <QVector>
  
  QT_BEGIN_NAMESPACE
  
  namespace Qt3DRender {
  
  class QRenderState;
  
  namespace Render {
  
  class RenderState;
  
  class Q_3DRENDERSHARED_PRIVATE_EXPORT RenderStateSet
  {
  public:
      RenderStateSet();
      ~RenderStateSet();
  
      template<typename GenericState>
      void addState(const GenericState &state)
      {
          addState(StateVariant::fromValue(state));
      }
  
      /**
       * @brief changeCost - metric of cost to change to this state-set from
       * a candidate previous state-set. This is used to find an optimal
       * ordering of state-sets when sending draw commands.
       * @param previousState
       * @return
       */
      int changeCost(RenderStateSet* previousState);
  
      StateMaskSet stateMask() const;
      void merge(const RenderStateSet *other);
  
      const QVector<StateVariant>& states() const noexcept { return m_states; }
      QVector<StateVariant>& states() noexcept { return m_states; }
  
      bool canAddStateOfType(StateMask type) const;
  
      /**
       * @brief contains - check if this set contains a matching piece of state
       * @param ds
       * @return
       */
      bool contains(const StateVariant &ds) const;
  
  private:
      bool hasStateOfType(StateMask type) const;
      bool allowMultipleStatesOfType(StateMask type) const;
  
  private:
      StateMaskSet m_stateMask;
      QVector<StateVariant> m_states;
  };
  
  template<>
  Q_3DRENDERSHARED_PRIVATE_EXPORT void RenderStateSet::addState<StateVariant>(const StateVariant &state);
  
  } // namespace Render
  } // namespace Qt3DRender
  
  QT_END_NAMESPACE
  
  #endif // QT3DRENDER_RENDER_RENDERSTATE_H
  