8.2 Graphics events 271
This callback specifies the function to be executed when a mouse button
is clicked:- Ifbtn=GLUTLEFTBUTTON, the left button has been clicked.
- Ifbtn=GLUTRIGHTBUTTON, the right button has been clicked.
- Ifbtn=GLUTMIDDLEBUTTON, the middle button has been clicked.
- Ifstate=GLUTUP, the button has been pressed.
- Ifstate=GLUTDOWN, the button has been released.
- The variablesxandyare the mouse coordinates.
void glutKeyboardFunc(void (*func)(unsigned char key,int x, int y));This callback specifies the function to be executed when a key is pressed.
The variablesxandyare the mouse coordinates.void glutMotionFunc(void (*func)(int x, int y));This callback specifies the function to be executed when the mouse is
moved while a button is pressed. The variablesxandyare the mouse
coordinates.void glutReshapeFunc(void (*func)(int width, int height));This callback specifies the function to be executed when the window is
being moved or resized. The arguments are the redrawn window width
and height.void glutTimerFunc(unsigned int msecs, void (*func)(int value), value);This callback prompts the execution of the function stated in the second
argument, called the “timer callback,” after a maximum delay ofmsecs
milliseconds.The parametervalueof the timer callback is the same as that in the
third argument of theglutTimerFunccallback. It is possible to register
multiple timer callbacks. Although a callback cannot be unregistered, it
can be deactivated using thevalueparameter.Timer callback
The following code implemented in the fileascii.ccgenerates a window
and prints all ASCII characters in animation using a time callback: