/// <summary>
/// Sets the overlay display callback for the current window.
/// </summary>
/// <param name="func">
/// The new overlay display callback function. See
/// <see cref="OverlayDisplayCallback" />.
/// </param>
/// <remarks>
/// <para>
/// <b>glutDisplayFunc</b> sets the overlay display callback for the current
/// window. The overlay display callback is functionally the same as the window's
/// display callback except that the overlay display callback is used to redisplay
/// the window's overlay.
/// </para>
/// <para>
/// When GLUT determines that the overlay display for the window needs to be
/// redisplayed, the overlay display callback for the window is called. Before
/// the callback, the current window is set to the window needing to be
/// redisplayed and the layer in use is set to the overlay. The overlay display
/// callback is called with no parameters. The entire overlay region should be
/// redisplayed in response to the callback (this includes ancillary buffers if
/// your program depends on their state).
/// </para>
/// <para>
/// GLUT determines when the overlay display callback should be triggered based on
/// the window's overlay redisplay state. The overlay redisplay state for a
/// window can be either set explicitly by calling
/// <see cref="glutPostOverlayRedisplay" /> or implicitly as the result of window
/// damage reported by the window system. Multiple posted overlay redisplays for
/// a window are coalesced by GLUT to minimize the number of overlay display
/// callbacks called.
/// </para>
/// <para>
/// Upon return from the overlay display callback, the overlay damaged state of
/// the window (returned by calling
/// <c>Glut.glutLayerGet(Glut.GLUT_OVERLAY_DAMAMGED)</c> is cleared.
/// </para>
/// <para>
/// The overlay display callback can be deregistered by passing <c>null</c> to
/// <see cref="glutOverlayDisplayFunc" />. The overlay display callback is
/// initially <c>null</c> when an overlay is established. See
/// <see cref="glutDisplayFunc" /> to understand how the display callback alone is
/// used if an overlay display callback is not registered.
/// </para>
/// </remarks>
/// <seealso cref="DisplayCallback" />
/// <seealso cref="OverlayDisplayCallback" />
/// <seealso cref="glutDisplayFunc" />
/// <seealso cref="glutPostOverlayRedisplay" />
// GLUTAPI void APIENTRY glutOverlayDisplayFunc(void (GLUTCALLBACK *func)(void));
public static void glutOverlayDisplayFunc([In] OverlayDisplayCallback func) {
overlayDisplayCallback = func;
__glutOverlayDisplayFunc(overlayDisplayCallback);
}
private static extern void __glutOverlayDisplayFunc(OverlayDisplayCallback func);
