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GLMINMAX(3G)                                                                                    GLMINMAX(3G)



NAME
       glMinmax - define minmax table


C SPECIFICATION
       void glMinmax( GLenum target,
                      GLenum internalformat,
                      GLboolean sink )


PARAMETERS
       target          The minmax table whose parameters are to be set.  Must be GL_MINMAX.

       internalformat  The   of entries in the minmax table.  Must be one of GL_ALPHA, GL_ALPHA4, GL_ALPHA8,
                       GL_ALPHA12, GL_ALPHA16, GL_LUMINANCE, GL_LUMINANCE4,  GL_LUMINANCE8,  GL_LUMINANCE12,
                       GL_LUMINANCE16,   GL_LUMINANCE_ALPHA,   GL_LUMINANCE4_ALPHA4,   GL_LUMINANCE6_ALPHA2,
                       GL_LUMINANCE8_ALPHA8,         GL_LUMINANCE12_ALPHA4,          GL_LUMINANCE12_ALPHA12,
                       GL_LUMINANCE16_ALPHA16,  GL_R3_G3_B2,  GL_RGB,  GL_RGB4,  GL_RGB5, GL_RGB8, GL_RGB10,
                       GL_RGB12, GL_RGB16, GL_RGBA, GL_RGBA2, GL_RGBA4, GL_RGB5_A1,  GL_RGBA8,  GL_RGB10_A2,
                       GL_RGBA12, or GL_RGBA16.

       sink            If  GL_TRUE,  pixels will be consumed by the minmax process and no drawing or texture
                       loading will take place.  If GL_FALSE, pixels will proceed to  the  final  conversion
                       process after minmax.

DESCRIPTION
       When  GL_MINMAX  is  enabled,  the RGBA components of incoming pixels are compared to the minimum and
       maximum values for each component, which are stored in the 2-element minmax table.  (The  first  ele-ment element
       ment  stores  the minima, and the second element stores the maxima.)  If a pixel component is greater
       than the corresponding component in the maximum element, then the maximum element is updated with the
       pixel  component value.  If a pixel component is less than the corresponding component in the minimum
       element, then the minimum element is updated with the pixel component value.  (In both cases, if  the
       internal   of  the  minmax table includes luminance, then the R color component of incoming pixels is
       used for comparison.)  The contents of the minmax table may be retrieved at a later time  by  calling
       glGetMinmax.   The  minmax operation is enabled or disabled by calling glEnable or glDisable, respec-tively, respectively,
       tively, with an argument of GL_MINMAX.

       glMinmax redefines the current minmax table to have entries of the specified by internalformat.   The
       maximum  element  is initialized with the smallest possible component values, and the minimum element
       is initialized with the largest possible component values.  The values in the previous minmax  table,
       if  any, are lost.  If sink is GL_TRUE, then pixels are discarded after minmax; no further processing
       of the pixels takes place, and no drawing, texture loading, or pixel readback will result.


NOTES
       glMinmax is present only if GL_ARB_imaging is returned when glGetString is called with an argument of
       GL_EXTENSIONS.

ERRORS
       GL_INVALID_ENUM is generated if target is not one of the allowable values.

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

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

ASSOCIATED GETS
       glGetMinmaxParameter

SEE ALSO
       glGetMinmax(3G), glResetMinmax(3G)




                                                                                                GLMINMAX(3G)