/// <summary>
/// Sets the Spaceball button callback for the current window.
/// </summary>
/// <param name="func">
/// The new Spaceball button callback function. See
/// <see cref="SpaceballButtonCallback" />.
/// </param>
/// <remarks>
/// <para>
/// <b>glutSpaceballButtonFunc</b> 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 <i>button</i> parameter
/// will be the button number (starting at one). The number of available
/// Spaceball buttons can be determined with
/// <c>glutDeviceGet(GLUT_NUM_SPACEBALL_BUTTONS)</c>. The <i>state</i> is either
/// <see cref="GLUT_UP" /> or <see cref="GLUT_DOWN" /> indicating whether the
/// callback was due to a release or press respectively.
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// Passing <c>null</c> to <b>glutSpaceballButtonFunc</b> disables the generation
/// of Spaceball button callbacks. When a new window is created, no Spaceball
/// button callback is initially registered.
/// </para>
/// </remarks>
/// <seealso cref="SpaceballButtonCallback" />
/// <seealso cref="glutDeviceGet" />
// GLUTAPI void APIENTRY glutSpaceballButtonFunc(void (GLUTCALLBACK *func)(int button, int state));
public static void glutSpaceballButtonFunc([In] SpaceballButtonCallback func) {
spaceballButtonCallback = func;
__glutSpaceballButtonFunc(spaceballButtonCallback);
}
private static extern void __glutSpaceballButtonFunc(SpaceballButtonCallback func);