glutSpecialUpFunc sets the special keyboard up (key release) callback for the current window. The special keyboard up callback is triggered when keyboard function or directional keys are released. The key callback parameter is a GLUT_KEY_* constant for the special key pressed. The x and y callback parameters indicate the mouse in window relative coordinates when the key was pressed. When a new window is created, no special up callback is initially registered and special key releases in the window are ignored. Passing NULL to glutSpecialUpFunc disables the generation of special up callbacks.
During a special up callback, glutGetModifiers may be called to determine the state of modifier keys when the key release generating the callback occurred.
To avoid the reporting of key release/press pairs due to auto repeat, use glutIgnoreKeyRepeat to ignore auto repeated keystrokes.
An implementation should do its best to provide ways to generate all the GLUT_KEY_* special keys. The available GLUT_KEY_* values are:
Note that the escape, backspace, and delete keys are generated as an ASCII character.
glutSpecialFunc , glutKeyboardFunc , glutKeyboardUpFunc , glutMouseFunc , glutSpaceballButtonFunc , glutButtonBoxFunc , glutTabletButtonFunc , glutGetModifiers , glutIgnoreKeyRepeat