glGetMinmaxEXT(3G)	       OpenGL Reference		    glGetMinmaxEXT(3G)

NAME    [Toc]    [Back]

     glGetMinmaxEXT - get minimum and maximum pixel values

C SPECIFICATION    [Toc]    [Back]

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

PARAMETERS    [Toc]    [Back]

     target  Must be GL_MINMAX_EXT.

     reset   If	GL_TRUE, all entries in	the minmax table that are actually
	     returned are reset	to their initial values.  (Other entries are
	     unaltered.)  If GL_FALSE, the minmax table	is unaltered.

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

     type    The type of the data to be	returned in values.  Must be one of
	     GL_UNSIGNED_BYTE, GL_BYTE,	GL_UNSIGNED_SHORT, GL_SHORT,
	     GL_UNSIGNED_INT, GL_INT, GL_FLOAT,	GL_UNSIGNED_BYTE_3_3_2_EXT,
	     GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
	     GL_UNSIGNED_INT_8_8_8_8_EXT, or GL_UNSIGNED_INT_10_10_10_2_EXT.

     values  A pointer to storage for the returned values.

DESCRIPTION    [Toc]    [Back]

     glGetMinmaxEXT returns the	accumulated minimum and	maximum	pixel values
     (computed on a per-component basis) in a one-dimensional image of width
     2.	 The first set of return values	are the	minima,	and the	second set of
     return values are the maxima.  The	format of the return values is
     determined	by format, and their type is determined	by type.

     No	pixel transfer operations are performed	on the return values, but
     pixel storage modes that are applicable to	1-dimensional images are
     performed.	 Color components that are requested in	the specified format,
     but which are not included	in the internal	format of the minmax table,
     are returned as zero.  The	assignment of internal color components	to the
     components	requested by format are	as follows:

		       Internal	Component   Result Component
		       _____________________________________
		       red		    red
		       green		    green
		       blue		    blue





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glGetMinmaxEXT(3G)	       OpenGL Reference		    glGetMinmaxEXT(3G)



		       alpha		    alpha
		       luminance	    red

     If	reset is GL_TRUE, the minmax table entries corresponding to the	return
     values are	reset to their initial values.	Minimum	and maximum values
     that are not returned are not modified, even if reset is GL_TRUE.

ERRORS    [Toc]    [Back]

     GL_INVALID_ENUM is	generated if target is not GL_MINMAX_EXT.

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

     If	type is	set to GL_UNSIGNED_BYTE_3_3_2_EXT,
     GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
     GL_UNSIGNED_INT_8_8_8_8_EXT, or GL_UNSIGNED_INT_10_10_10_2_EXT and	the
     EXT_packed_pixels extension is not	supported then a GL_INVALID_ENUM error
     is	generated.


MACHINE	DEPENDENCIES
     On	RealityEngine, RealityEngine2, and VTX systems,	histogram and minmax
     may not be	used when rendering to pixmaps.

SEE ALSO    [Toc]    [Back]

     glMinmaxEXT, glResetMinmaxEXT, glGetMinmaxParameterEXT.


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