Name

    WGL_I3D_gamma

Name Strings

    WGL_I3D_gamma

Contact

    Dale Kirkland, Intense3D (kirkland 'at' intense3d.com)

Status

    Complete

Version

    Date: 04/17/2000   Revision 1.0

Number

    251

Dependencies

    The extension is written against the OpenGL 1.2.1 Specification
    although it should work on any previous OpenGL specification.

    The WGL_EXT_extensions_string extension is required.

Overview

    The gamma extension provides an interface to read and load the
    gamma table.  Other options such as having gamma only affect
    OpenGL windows can also be set.

IP Status

    None

Issues

    None

New Procedures and Functions

    BOOL wglGetGammaTableParametersI3D(HDC hDC,
                                       int iAttribute,
                                       int *piValue)

    BOOL wglSetGammaTableParametersI3D(HDC hDC,
                                       int iAttribute,
                                       const int *piValue)

    BOOL wglGetGammaTableI3D(HDC hDC,
                             int iEntries,
                             USHORT *puRed,
                             USHORT *puGreen,
                             USHORT *puBlue)

    BOOL wglSetGammaTableI3D(HDC hDC,
                             int iEntries,
                             const USHORT *puRed,
                             const USHORT *puGreen,
                             const USHORT *puBlue)

New Tokens

    Accepted by the <iAttribute> parameter of wglGetGammaTableParametersI3D:

      WGL_GAMMA_TABLE_SIZE_I3D            0x204E
      WGL_GAMMA_EXCLUDE_DESKTOP_I3D       0x204F

    Accepted by the <iAttribute> parameter of wglSetGammaTableParametersI3D:

      WGL_GAMMA_EXCLUDE_DESKTOP_I3D       0x204F

Additions to Chapter 2 of the OpenGL 1.2.1 Specification (OpenGL Operation)

    None

Additions to Chapter 3 of the OpenGL 1.2.1 Specification (Rasterization)

    None

Additions to Chapter 4 of the OpenGL 1.2.1 Specification (Per-Fragment
Operations and the Frame Buffer)

    None

Additions to Chapter 5 of the OpenGL 1.2.1 Specification (Special Functions)

    None

Additions to Chapter 6 of the OpenGL 1.2.1 Specification (State and
State Requests)

    None

Additions to Appendix A of the OpenGL 1.2.1 Specification (Invariance)

    None

Additions to the WGL Specification

    Gamma correction for each monitor that supports a gamma table is
    controlled by loading the gamma table and setting the appropriate
    parameters.  The function wglSetGammaTableI3D loads the gamma
    table:

      BOOL wglSetGammaTableI3D(HDC hDC,
                               int iEntries,
                               const USHORT *puRed,
                               const USHORT *puGreen,
                               const USHORT *puBlue)

    <hDC> is a device context for the graphics adapter or a window
    residing on a monitor whose graphics adapter supports the gamma
    extension.  For multiple monitor systems, only the gamma table
    associated with <hDC> is loaded.

    The red, green, and blue data for the gamma table are pointed to by
    <puRed>, <puGreen> and <puBlue> respectively.  Each color array
    must contain <iEntries> entries.  Gamma entries     specified outside
    the hardware gamma table are ignored.

    The red, green, and blue data is defined using 16-bit precision.
    If the hardware gamma table has less than 16 bits of precision, the
    data is shifted down so that only the most-significant bits are
    used without rounding.

    The current gamma table can be obtained by calling the function
    wglGetGammaTableI3D:

      BOOL wglGetGammaTableI3D(HDC hDC,
                               int iEntries,
                               USHORT *puRed,
                               USHORT *puGreen,
                               USHORT *puBlue)

    <hDC> is a device context for the graphics adapter or a window
    residing on a monitor whose graphics adapter supports the gamma
    extension.  For multiple monitor systems, only the gamma table
    associated with <hDC> is read.

    <puRed>, <puGreen> and <puBlue> each point to an unsigned-short
    array containing <iEntries>.  If <iEntries> is larger than the
    hardware gamma table, only the number of entries that correspond to
    the size of the hardware gamma table will be returned.

    The red, green and blue data is defined using 16-bit precision
    according to the description above.  If the hardware gamma table
    has less than 16 bits of precision, the data is shifted up.

    Gamma table parameters can be set with the function
    wglSetGammaTableParametersI3D:

      BOOL wglSetGammaTableParametersI3D(HDC hDC,
                                         int iAttribute,
                                         const int *piValue)

    <hDC> is a device context for the graphics adapter or a window
    residing on a monitor whose graphics adapter supports the gamma
    extension.  For multiple monitor systems, only the gamma table
    associated with <hDC> is set.

    <iAttribute> must be one of the following values:

      WGL_GAMMA_EXCLUDE_DESKTOP_I3D
            If the value pointed to by <piValue> is non-zero, only the
            contents of OpenGL windows are gamma corrected; the
            desktop will not be gamma corrected.  If the value pointed
            to by <piValue> is zero, all windows and the desktop are
            gamma corrected.  This value defaults to zero.

    Gamma table parameters can be queried with the function
    wglGetGammaTableParametersI3D:

      BOOL wglGetGammaTableParametersI3D(HDC hDC,
                                         int iAttribute,
                                         int *piValue)

    <hDC> is a device context for the graphics adapter or a window
    residing on a monitor whose graphics adapter supports the gamma
    extension.  For multiple monitor systems, only the gamma table
    parameters associated with <hDC> are returned.

    <iAttribute> must be one of the following values:

      WGL_GAMMA_EXCLUDE_DESKTOP_I3D
            Returns the current setting for desktop gamma correction.
            If the value returned in the location pointed to by
            <piValue> is non-zero, only the contents of OpenGL windows
            are gamma corrected; the desktop will not be gamma
            corrected.

      WGL_GAMMA_TABLE_SIZE_I3D
            Returns the number of entries in the hardware gamma table.

Dependencies on WGL_EXT_extensions_string

    Because there is no way to extend wgl, these calls are defined in
    the ICD and can be called by obtaining the address with
    wglGetProcAddress.  Because this extension is a WGL extension, it
    is not included in the GL_EXTENSIONS string.  Its existence can be
    determined with the WGL_EXT_extensions_string extension.

Errors

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

      ERROR_DC_NOT_FOUND         The <hDC> was not valid.

      ERROR_NO_SYSTEM_RESOURCES  There is no support for a gamma table
                                 for the adapter specified by <hDC>.

      ERROR_INVALID_DATA         <iAttribute> is not a valid value.

      ERROR_INVALID_DATA         <iEntries> is not a positive value.

New State

    None

New Implementation Dependent State

    None

Revision History

    11/24/1999  0.1  First draft.
    11/29/1999  0.2  Changed wglGetGammaTableI3D and
                     wglSetGammaTableI3D to accept three pointers, one
                     each for the red, green, and blue data for the
                     gamma table.
    04/17/2000  1.0  Fixed a few typos.
                     Driver released to ISVs.