displayOverlay("POSIT","We lost the 4 corners' detection quite often (the red circles disappear). This demo is only to illustrate how to use OpenGL callback.\n -- Press ESC to exit.",10000);
displayOverlay("POSIT","We lost the 4 corners' detection quite often (the red circles disappear). This demo is only to illustrate how to use OpenGL callback.\n -- Press ESC to exit.",10000);