wglSwapLayerBuffers

The wglSwapLayerBuffers function swaps the front and back buffers in the overlay, underlay, and main planes of the window referenced by a specified device context.

BOOL wglSwapLayerBuffers(
  HDC  hdc,       // device context whose layer plane buffers are to 
                  // be swapped
  UINT  fuPlanes  // specifies the overlay, underlay and main planes 
                  // to be swapped
);

Parameters

• hdc
  Specifies the device context of a window whose layer plane palette is to be realized into the physical palette.
• fuPlanes
  Specifies the overlay, underlay, and main planes whose front and back buffers are to be swapped. The bReserved member of the PIXELFORMATDESCRIPTOR structure specifies the number of overlay and underlay planes. The fuPlanes parameter is a bitwise combination of the following values.

  Value	Meaning
  WGL_SWAP_MAIN_PLANE	Swaps the front and back buffers of the main plane.
  WGL_SWAP_OVERLAYi	Swaps the front and back buffers of the overlay plane i, where i is an integer between 1 and 15. WGL_SWAP_OVERLAY1 identifies the first overlay plane over the main plane, WGL_SWAP_OVERLAY2 identifies the second overlay plane over the first overlay plane, and so on.
  WGL_SWAP_UNDERLAYi	Swaps the front and back buffers of the underlay plane i, where i is an integer between 1 and 15. WGL_SWAP_UNDERLAY1 identifies the first underlay plane under the main plane, WGL_SWAP_UNDERLAY2 identifies the second underlay plane under the first underlay plane, and so on.

Return Values

If the function succeeds, the return value is TRUE. If the function fails, the return value is FALSE. To get extended error information, call GetLastError.

Remarks

When a layer plane doesn't include a back buffer, calling the wglSwapLayerBuffers function has no effect on that layer plane. After you call wglSwapLayerBuffers, the state of the back buffer content is given in the corresponding LAYERPLANEDESCRIPTOR structure of the layer plane or in the PIXELFORMATDESCRIPTOR structure of the main plane. The wglSwapLayerBuffers function swaps the front and back buffers in the specified layer planes simultaneously.

Some devices don't support swapping layer planes individually; they swap all layer planes as a group. When the PFD_SWAP_LAYER_BUFFERS flag of the PIXELFORMATDESCRIPTOR structure is set, it indicates that a device can swap individual layer planes and that you can call wglSwapLayerBuffers.

With applications that use multiple threads, before calling wglSwapLayerBuffers, clear all drawing commands in all threads drawing to the same window.

Requirements

**  Windows NT/2000:** Requires Windows NT 3.5 or later.
**  Windows 95/98:** Requires Windows 95 or later. Available as a redistributable for Windows 95.
**  Header:** Declared in wingdi.h.
**  Import Library:** Use opengl32.lib.

See Also

OpenGL on Windows NT, Windows 2000, and Windows 95/98, WGL Functions, LAYERPLANEDESCRIPTOR, PIXELFORMATDESCRIPTOR, SwapBuffers