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GLGETHISTOGRAM(3G)                                                                        GLGETHISTOGRAM(3G)



NAME
       glGetHistogram - get histogram table


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


PARAMETERS
       target  Must be GL_HISTOGRAM.

       reset   If  GL_TRUE, each component counter that is actually returned is reset to zero.  (Other coun-ters counters
               ters are unaffected.)  If GL_FALSE, none of the counters in the histogram table is  modified.

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

       type    The type of values to be returned in values.  Symbolic constants  GL_UNSIGNED_BYTE,  GL_BYTE,
               GL_BITMAP,     GL_UNSIGNED_SHORT,     GL_SHORT,     GL_UNSIGNED_INT,     GL_INT,    GL_FLOAT,
               GL_UNSIGNED_BYTE_3_3_2,         GL_UNSIGNED_BYTE_2_3_3_REV,          GL_UNSIGNED_SHORT_5_6_5,
               GL_UNSIGNED_SHORT_5_6_5_REV,     GL_UNSIGNED_SHORT_4_4_4_4,    GL_UNSIGNED_SHORT_4_4_4_4_REV,
               GL_UNSIGNED_SHORT_5_5_5_1,      GL_UNSIGNED_SHORT_1_5_5_5_REV,       GL_UNSIGNED_INT_8_8_8_8,
               GL_UNSIGNED_INT_8_8_8_8_REV,  GL_UNSIGNED_INT_10_10_10_2,  and GL_UNSIGNED_INT_2_10_10_10_REV
               are accepted.

       values  A pointer to storage for the returned histogram table.

DESCRIPTION
       glGetHistogram returns the current histogram table as a one-dimensional image with the same width  as
       the  histogram.   No  pixel  transfer operations are performed on this image, but pixel storage modes
       that are applicable to 1D images are honored.

       Color components that are requested in the specified format, but which are not included in the inter-nal internal
       nal  of the histogram, are returned as zero.
       The assignments of internal color components to the components requested by format are:

        Internal Component  Resulting Component
        red                 red
        green               green
        blue                blue
        alpha               alpha
        luminance           red



NOTES
       glGetHistogram is present only if GL_ARB_imaging is returned when glGetString is called with an argu-ment argument
       ment of GL_EXTENSIONS.

ERRORS
       GL_INVALID_ENUM is generated if target is not GL_HISTOGRAM.

       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 glGetHistogram is executed between the execution of glBegin  and
       the corresponding execution of glEnd.


       GL_INVALID_OPERATION     is     generated    if    type    is    one    of    GL_UNSIGNED_BYTE_3_3_2,
       GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5, or GL_UNSIGNED_SHORT_5_6_5_REV and format is not
       GL_RGB.

       GL_INVALID_OPERATION    is    generated    if    type    is    one    of   GL_UNSIGNED_SHORT_4_4_4_4,
       GL_UNSIGNED_SHORT_4_4_4_4_REV,       GL_UNSIGNED_SHORT_5_5_5_1,        GL_UNSIGNED_SHORT_1_5_5_5_REV,
       GL_UNSIGNED_INT_8_8_8_8,       GL_UNSIGNED_INT_8_8_8_8_REV,       GL_UNSIGNED_INT_10_10_10_2,      or
       GL_UNSIGNED_INT_2_10_10_10_REV and format is neither GL_RGBA nor GL_BGRA.

SEE ALSO
       glHistogram(3G), glResetHistogram(3G), glGetHistogramParameter(3G)




                                                                                          GLGETHISTOGRAM(3G)