LAYERPLANEDESCRIPTOR

The LAYERPLANEDESCRIPTOR structure describes the pixel format of a drawing surface.

typedef struct tagLAYERPLANEDESCRIPTOR { // pfd   
  WORD  nSize; 
  WORD  nVersion; 
  DWORD dwFlags; 
  BYTE  iPixelType; 
  BYTE  cColorBits; 
  BYTE  cRedBits; 
  BYTE  cRedShift; 
  BYTE  cGreenBits; 
  BYTE  cGreenShift; 
  BYTE  cBlueBits; 
  BYTE  cBlueShift; 
  BYTE  cAlphaBits; 
  BYTE  cAlphaShift; 
  BYTE  cAccumBits; 
  BYTE  cAccumRedBits; 
  BYTE  cAccumGreenBits; 
  BYTE  cAccumBlueBits; 
  BYTE  cAccumAlphaBits; 
  BYTE  cDepthBits; 
  BYTE  cStencilBits; 
  BYTE  cAuxBuffers; 
  BYTE  iLayerPlane 
  BYTE  bReserved; 
  COLORREF crTransparent; 
} LAYERPLANEDESCRIPTOR; 

Members

nSize
Specifies the size of this data structure. Set this value to sizeof(LAYERPLANEDESCRIPTOR).
nVersion
Specifies the version of this data structure. Set this value to 1.
dwFlags
A set of bit flags that specify properties of the layer plane. The properties are generally not mutually exclusive; any combination of bit flags can be set, with the exceptions noted. The following bit flag constants are defined.
Value Meaning
LPD_SUPPORT_OPENGL The layer plane supports OpenGL drawing.
LPD_SUPPORT_GDI The layer plane supports GDI drawing. The current implementation of OpenGL doesn't support this flag.
LPD_DOUBLEBUFFER The layer plane is double-buffered. A layer plane can be double-buffered even when the main plane is single-buffered and vice versa.
LPD_STEREO The layer plane is stereoscopic. A layer plane can be stereoscopic even when the main plane is monoscopic and vice versa.
LPD_SWAP_EXCHANGE In a double-buffered layer plane, swapping the color buffer exchanges the front buffer and back buffer contents. The back buffer then contains the contents of the front buffer before the swap. This flag is a hint only and might not be provided by a driver.
LPD_SWAP_COPY In a double-buffered layer plane, swapping the color buffer copies the back buffer contents to the front buffer. The swap does not affect the back buffer contents. This flag is a hint only and might not be provided by a driver.
LPD_TRANSPARENT The crTransparent member of this structure contains a transparent color or index value that enables underlying layers to show through this layer. All layer planes, except the lowest-numbered underlay layer, have a transparent color or index.
LPD_SHARE_DEPTH The layer plane shares the depth buffer with the main plane.
LPD_SHARE_STENCIL The layer plane shares the stencil buffer with the main plane.
LPD_SHARE_ACCUM The layer plane shares the accumulation buffer with the main plane.

iPixelType
Specifies the type of pixel data. The following types are defined.
Value Meaning
LPD_TYPE_RGBA RGBA pixels. Each pixel has four components: red, green, blue, and alpha.
LPD_TYPE_COLORINDEX Color-index pixels. Each pixel uses a color-index value.

cColorBits
Specifies the number of color bitplanes in each color buffer. For RGBA pixel types, it is the size of the color buffer, excluding the alpha bitplanes. For color-index pixels, it is the size of the color-index buffer.
cRedBits
Specifies the number of red bitplanes in each RGBA color buffer.
cRedShift
Specifies the shift count for red bitplanes in each RGBA color buffer.
cGreenBits
Specifies the number of green bitplanes in each RGBA color buffer.
cGreenShift
Specifies the shift count for green bitplanes in each RGBA color buffer.
cBlueBits
Specifies the number of blue bitplanes in each RGBA color buffer.
cBlueShift
Specifies the shift count for blue bitplanes in each RGBA color buffer.
cAlphaBits
Specifies the number of alpha bitplanes in each RGBA color buffer. Alpha bitplanes are not supported.
cAlphaShift
Specifies the shift count for alpha bitplanes in each RGBA color buffer. Alpha bitplanes are not supported.
cAccumBits
Specifies the total number of bitplanes in the accumulation buffer.
cAccumRedBits
Specifies the number of red bitplanes in the accumulation buffer.
cAccumGreenBits
Specifies the number of green bitplanes in the accumulation buffer.
cAccumBlueBits
Specifies the number of blue bitplanes in the accumulation buffer.
cAccumAlphaBits
Specifies the number of alpha bitplanes in the accumulation buffer.
cDepthBits
Specifies the depth of the depth (z-axis) buffer.
cStencilBits
Specifies the depth of the stencil buffer.
cAuxBuffers
Specifies the number of auxiliary buffers. Auxiliary buffers are not supported.
iLayerType
Specifies the layer plane number. Positive values of iLayerType identify overlay planes, where 1 is the first overlay plane over the main plane, 2 is the second overlay plane over the first overlay plane, and so on. Negative values identify underlay planes, where 1 is the first underlay plane under the main plane, 2 is the second underlay plane under the first underlay plane, and so on. The number of overlay and underlay planes is given in the bReserved member of the PIXELFORMATDESCRIPTOR structure.
bReserved
Not used. Must be zero.
crTransparent
When the LPD_TRANSPARENT flag is set, specifies the transparent color or index value. Typically the value is zero.

Remarks

Please notice, as documented above, that certain layer plane properties are not supported in the current implementation. The implementation is the Microsoft GDI software implementation of OpenGL. Hardware manufacturers that enhance parts of OpenGL may support some layer plane properties not supported by the generic implementation.

See Also

OpenGL on Windows NT, Windows 2000, and Windows 95/98, Structures, PIXELFORMATDESCRIPTOR, wglCreateLayerContext, wglDescribeLayerPlane, wglGetLayerPaletteEntries, wglRealizeLayerPalette, wglSetLayerPaletteEntries, wglSwapLayerBuffers


  

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