void OnGUI()
 {
     if (GUILayout.Button("Image Target", GUILayout.Width(100), GUILayout.Height(50)))
     {
         LoadAboutScene("ImageTargets");
         SamplesMainMenu.LoadScene(SamplesMainMenu.LoadingScene);
     }
 }
 public void LoadMenuScene()
 {
     // called by "<" button on About screen
     // called by "Vuforia Samples" button in AR scene UI menu
     SamplesMainMenu.LoadScene(SamplesMainMenu.MenuScene);
 }
 public void OnStartAR()
 {
     // called by OK button on About screen
     SamplesMainMenu.LoadScene(SamplesMainMenu.LoadingScene);
 }
 public void LoadMenuScene()
 {
     // called by "Vuforia Samples" button in AR scene UI menu
     // also called below in Update() if Android Back button pressed
     SamplesMainMenu.LoadScene(SamplesMainMenu.MenuScene);
 }