Next: 7.13 glutButtonBoxFunc Up: 7 Callback Registration Previous: 7.11 glutSpaceballRotateFunc

## 7.12 glutSpaceballButtonFunc

`glutSpaceballButtonFunc` sets the Spaceball button callback for the current window.

Usage

    void glutSpaceballButtonFunc(void (*func)(int button, int state));

`func`
  The new entry callback function.

Description

`glutSpaceballButtonFunc` sets the Spaceball button callback for the current window. The Spaceball button callback for a window is called when the window has Spaceball input focus (normally, when the mouse is in the window) and the user generates Spaceball button presses. The `button` parameter will be the button number (starting at one). The number of available Spaceball buttons can be determined with `glutDeviceGet(GLUT_NUM_SPACEBALL_BUTTONS)`. The `state` is either `GLUT_UP` or `GLUT_DOWN` indicating whether the callback was due to a release or press respectively.

Registering a Spaceball button callback when a Spaceball device is not available is ineffectual and not an error. In this case, no Spaceball button callbacks will be generated.

Passing `NULL` to `glutSpaceballButtonFunc` disables the generation of Spaceball button callbacks. When a new window is created, no Spaceball button callback is initially registered.

Next: 7.13 glutButtonBoxFunc Up: 7 Callback Registration Previous: 7.11 glutSpaceballRotateFunc