glGetConvolutionFilter(3G)     OpenGL Reference	    glGetConvolutionFilter(3G)

NAME    [Toc]    [Back]

     glGetConvolutionFilter - get current 1D or	2D convolution filter kernel

C SPECIFICATION    [Toc]    [Back]

     void glGetConvolutionFilter( GLenum target,
				  GLenum format,
				  GLenum type,
				  GLvoid *image	)

PARAMETERS    [Toc]    [Back]

     target  The filter	to be retrieved.  Must be one of GL_CONVOLUTION_1D or
	     GL_CONVOLUTION_2D.

     format  Format of the output image.  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    Data type of components in	the output image.  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.

     image   Pointer to	storage	for the	output image.

DESCRIPTION    [Toc]    [Back]

     glGetConvolutionFilter returns the	current	1D or 2D convolution filter
     kernel as an image.  The one- or two-dimensional image is placed in image
     according to the specifications in	format and type.  No pixel transfer
     operations	are performed on this image, but the relevant pixel storage
     modes are applied.

     Color components that are present in format but not included in the
     internal format of	the filter are returned	as zero.  The assignments of
     internal color components to the components of format are as follows.













									Page 1






glGetConvolutionFilter(3G)     OpenGL Reference	    glGetConvolutionFilter(3G)



		    _________________________________________
		     Internal Component	  Resulting Component
		     ________________________________________
		     Red		  Red
		     Green		  Green
		     Blue		  Blue
		     Alpha		  Alpha
		     Luminance		  Red
		     Intensity		  Red
		     ________________________________________

NOTES    [Toc]    [Back]

     glGetConvolutionFilter 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.

     The current separable 2D filter must be retrieved with
     glGetSeparableFilter rather than glGetConvolutionFilter.

ERRORS    [Toc]    [Back]

     GL_INVALID_ENUM is	generated if target is not one of the allowable
     values.

     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 glGetConvolutionFilter 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.

ASSOCIATED GETS    [Toc]    [Back]

     glGetConvolutionParameter








									Page 2






glGetConvolutionFilter(3G)     OpenGL Reference	    glGetConvolutionFilter(3G)



SEE ALSO
     glGetSeparableFilter, glConvolutionParameter, glConvolutionFilter1D,
     glConvolutionFilter2D


									PPPPaaaaggggeeee 3333