glGetHistogram

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  counters  are  unaffected.)   If
	       GL_FALSE, none of the counters in the histogram table is modi-
	       fied.

       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	 con-
	       stants	    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-dimen-
       sional 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  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 argument 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 val-
       ues.

       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 for-
       mat is neither GL_RGBA nor GL_BGRA.

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



							   GLGETHISTOGRAM(3G)