glGetHistogram(3G)	       OpenGL Reference		    glGetHistogram(3G)

NAME    [Toc]    [Back]

     glGetHistogram - get histogram table

C SPECIFICATION    [Toc]    [Back]

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

PARAMETERS    [Toc]    [Back]

     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    [Toc]    [Back]

     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 internal format of	the histogram, are returned as
     zero.










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glGetHistogram(3G)	       OpenGL Reference		    glGetHistogram(3G)



     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    [Toc]    [Back]

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

     GL_ABGR_EXT is valid only if the EXT_abgr extension is supported.

ERRORS    [Toc]    [Back]

     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	not GL_RGBA, GL_BGRA or	GL_ABGR_EXT.

SEE ALSO    [Toc]    [Back]

     glHistogram, glResetHistogram, glGetHistogramParameter


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