glGetConvolutionFilter

GLGETCONVOLUTIONFILTER(3G)			   GLGETCONVOLUTIONFILTER(3G)



NAME
       glGetConvolutionFilter  - get current 1D or 2D convolution filter ker-
       nel


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


PARAMETERS
       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_LUMINANCE, or GL_LUMINANCE_ALPHA.

       type    Data  type  of  components in the output image.	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.

       image   Pointer to storage for the output image.

DESCRIPTION
       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	  of  the  filter  are	returned as zero.  The assignments of
       internal color components to the components of format are as  follows.




















		      -----------------------------------------
		      Internal Component   Resulting Component
		      -----------------------------------------
		      Red		   Red
		      Green		   Green
		      Blue		   Blue
		      Alpha		   Alpha
		      Luminance		   Red
		      Intensity		   Red
		      -----------------------------------------

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

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

ERRORS
       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 val-
       ues.

       GL_INVALID_OPERATION is generated if  glGetConvolutionFilter  is	 exe-
       cuted 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.

ASSOCIATED GETS
       glGetConvolutionParameter

SEE ALSO
       glGetSeparableFilter(3G),		  glConvolutionParameter(3G),
       glConvolutionFilter1D(3G), glConvolutionFilter2D(3G)



						   GLGETCONVOLUTIONFILTER(3G)