glGetMinmaxEXT(3G)

NAME
     glGetMinmaxEXT - get minimum and maximum pixel values


C SPECIFICATION
     void glGetMinmaxEXT( GLenum target,
                          GLboolean reset,
                          GLenum format,
                          GLenum type,
                          GLvoid *values )


PARAMETERS
     target  Must be GL_MINMAX_EXT.

     reset   If GL_TRUE, all entries in the minmax table that are actually
             returned are reset to their initial values.  (Other entries are
             unaltered.)  If GL_FALSE, the minmax table is unaltered.

     format  The format of the data to be returned in values.  Must be one of
             GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA,
             GL_ABGR_EXT, GL_LUMINANCE, or GL_LUMINANCE_ALPHA.

     type    The type of the data to be returned in values.  Must be one of
             GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT,
             GL_UNSIGNED_INT, GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2_EXT,
             GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
             GL_UNSIGNED_INT_8_8_8_8_EXT, or GL_UNSIGNED_INT_10_10_10_2_EXT.

     values  A pointer to storage for the returned values.

DESCRIPTION
     glGetMinmaxEXT returns the accumulated minimum and maximum pixel values
     (computed on a per-component basis) in a one-dimensional image of width
     2.  The first set of return values are the minima, and the second set of
     return values are the maxima.  The format of the return values is
     determined by format, and their type is determined by type.

     No pixel transfer operations are performed on the return values, but
     pixel storage modes that are applicable to 1-dimensional images are
     performed.  Color components that are requested in the specified format,
     but which are not included in the internal format of the minmax table,
     are returned as zero.  The assignment of internal color components to the
     components requested by format are as follows:

                       Internal Component   Result Component
                       _____________________________________
                       red                  red
                       green                green
                       blue                 blue
                       alpha                alpha
                       luminance            red

     If reset is GL_TRUE, the minmax table entries corresponding to the return
     values are reset to their initial values.  Minimum and maximum values
     that are not returned are not modified, even if reset is GL_TRUE.

ERRORS
     GL_INVALID_ENUM is generated if target is not GL_MINMAX_EXT.

     GL_INVALID_ENUM is generated if format is not one of the allowable
     values.

     GL_INVALID_ENUM is generated if type is not one of the allowable values.

     GL_INVALID_OPERATION is generated if glGetMinmaxEXT is executed between
     the execution of glBegin and the corresponding execution of glEnd.

     If type is set to GL_UNSIGNED_BYTE_3_3_2_EXT,
     GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
     GL_UNSIGNED_INT_8_8_8_8_EXT, or GL_UNSIGNED_INT_10_10_10_2_EXT and the
     EXT_packed_pixels extension is not supported then a GL_INVALID_ENUM error
     is generated.

SEE ALSO
     glMinmaxEXT, glResetMinmaxEXT, glGetMinmaxParameterEXT.