void OnEnable()
 {
     if (m_AARProjectorRenderingManager == null)
     {
         m_AARProjectorRenderingManager = target as AARProjectorRenderingManager;
     }
 }
 void OnEnable()
 {
     // init instance singleton
     if (_instance != null && _instance != this)
     {
         Destroy(this.gameObject);
     }
     else
     {
         _instance = this;
     }
 }