glutSpaceballButtonFunc - Man Page
Sets a spaceball button callback.
Library
OpenGLUT - input
Synopsis
#include <openglut.h>
void 
 glutSpaceballButtonFunc(void( *callback )( int button, int state ));
Parameters
callback
Client spaceball button hook.
Description
This function registers a callback for a spaceball to report buttons. A spaceball has six axes of freedom (three of motion and three of orientation), plus buttons. The spaceball has glutDeviceGet(
GLUT_NUM_SPACEBALL_BUTTONS)
and numbers them from 1. Button state is either
GLUT_UP
or
GLUT_DOWN.
The callback is bound to the
  
 current window
 . 
Caveats
OpenGLUT does not implement spaceball support.
In contrast, mouse buttons are numbered from 0 in the GLUT API. This is a wrinkle.
See Also
glutSpaceballRotateFunc(3) glutSpaceballMotiononFunc,(3)