Next: 7.15 glutTabletMotionFunc Up: 7 Callback Registration Previous: 7.13 glutButtonBoxFunc

## 7.14 glutDialsFunc

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

Usage

    void glutDialsFunc(void (*func)(int dial, int value));

`func`
  The new entry callback function.

Description

`glutDialsFunc` sets the dial & button box dials callback for the current window. The dial & button box dials 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 dial changes. The `dial` parameter will be the dial number (starting at one). The number of available dial & button box dials can be determined with `glutDeviceGet(GLUT_NUM_DIALS)`. The `value` measures the absolute rotation in degrees. Dial values do not ``roll over'' with each complete rotation but continue to accumulate degrees (until the `int` dial value overflows).

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

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

Next: 7.15 glutTabletMotionFunc Up: 7 Callback Registration Previous: 7.13 glutButtonBoxFunc