fglGetHistogram(3G)

NAME
     fglGetHistogram - get histogram table


FORTRAN SPECIFICATION
     SUBROUTINE fglGetHistogram( INTEGER*4 target,
                                 LOGICAL*1 reset,
                                 INTEGER*4 format,
                                 INTEGER*4 type,
                                 CHARACTER*8 values )


PARAMETERS
     target  Must be GL_HISTOGRAM.

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

     format  The format 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_ABGR_EXT, 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
     fglGetHistogram 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 internal format 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
     fglGetHistogram is present only if GL_ARB_imaging is returned when
     fglGetString is called with an argument of GL_EXTENSIONS.

     GL_ABGR_EXT is valid only if the EXT_abgr extension is supported.

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 fglGetHistogram is executed between
     the execution of fglBegin and the corresponding execution of fglEnd.

     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 not GL_RGBA, GL_BGRA or GL_ABGR_EXT.


SEE ALSO
     fglHistogram, fglResetHistogram, fglGetHistogramParameter