Next: 7.14 glutDialsFunc Up: 7 Callback Registration Previous: 7.12 glutSpaceballButtonFunc

## 7.13 glutButtonBoxFunc

`glutButtonBoxFunc` sets the dial & button box button callback for the current window.

Usage

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

`func`
  The new entry callback function.

Description

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

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

Passing `NULL` to `glutButtonBoxFunc` disables the generation of dial & button box button callbacks. When a new window is created, no dial & button box button callback is initially registered.

Next: 7.14 glutDialsFunc Up: 7 Callback Registration Previous: 7.12 glutSpaceballButtonFunc