_C_ License Applicability. Except to the extent portions of this file are
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_C_ Software License B, Version 1.1 (the "License"), the contents of this
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_C_ Note that, as provided in the License, the Software is distributed on an
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_C_ 
_C_ Original Code. The Original Code is: OpenGL Sample Implementation,
_C_ Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
_C_ Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
_C_ Copyright in any portions created by third parties is as indicated
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_C_ Additional Notice Provisions: The application programming interfaces
_C_ established by SGI in conjunction with the Original Code are The
_C_ OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
_C_ April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
_C_ 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
_C_ Window System(R) (Version 1.3), released October 19, 1998. This software
_C_ was created using the OpenGL(R) version 1.2.1 Sample Implementation
_C_ published by SGI, but has not been independently verified as being
_C_ compliant with the OpenGL(R) version 1.2.1 Specification.
_C_
_C_ The first character in this file must be an '_'!
_C_ Anything on a line after _C_ is ignored
_define(_filters,tbl)_C_
_header(GetConvolutionFilter,get current 1D or 2D convolution filter kernel)
_names(GetConvolutionFilter)
_define(@<__target>@,@<_param1>@)_C_
_define(@<__format>@,@<_param2>@)_C_
_define(@<__type>@,@<_param3>@)_C_
_define(@<__image>@,@<_param4>@)_C_
.SH PARAMETERS
_phead(__target)
The filter to be retrieved.
Must be one of
_const(CONVOLUTION_1D) or
_const(CONVOLUTION_2D).
_phead(__format)
Format of the output image.
Must be one of
_const(RED),
_const(GREEN),
_const(BLUE),
_const(ALPHA),
_const(RGB),
_const(BGR),
_const(RGBA),
_const(BGRA),
_const(LUMINANCE), or
_const(LUMINANCE_ALPHA).
_phead(__type)
Data type of components in the output image.
Symbolic constants
_const(UNSIGNED_BYTE),
_const(BYTE),
_const(BITMAP),
_const(UNSIGNED_SHORT),
_const(SHORT),
_const(UNSIGNED_INT),
_const(INT),
_const(FLOAT),
_const(UNSIGNED_BYTE_3_3_2),
_const(UNSIGNED_BYTE_2_3_3_REV),
_const(UNSIGNED_SHORT_5_6_5),
_const(UNSIGNED_SHORT_5_6_5_REV),
_const(UNSIGNED_SHORT_4_4_4_4),
_const(UNSIGNED_SHORT_4_4_4_4_REV),
_const(UNSIGNED_SHORT_5_5_5_1),
_const(UNSIGNED_SHORT_1_5_5_5_REV),
_const(UNSIGNED_INT_8_8_8_8),
_const(UNSIGNED_INT_8_8_8_8_REV),
_const(UNSIGNED_INT_10_10_10_2), and
_const(UNSIGNED_INT_2_10_10_10_REV)
are accepted.
_phead(__image)
Pointer to storage for the output image.
.SH DESCRIPTION
_cmnd 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.
.sp
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.
.br
.bp
.TS
center;
lb lb
l l.
_
Internal Component	Resulting Component
_
Red	Red
Green	Green
Blue	Blue
Alpha	Alpha
Luminance	Red
Intensity	Red
_
.TE
.SH NOTES
_cmnd is present only if _arbstring(imaging) is returned when _cmnd(GetString)
is called with an argument of _const(EXTENSIONS).
.P
The current separable 2D filter must be retrieved with
_cmnd(GetSeparableFilter) rather than _cmnd.
.SH ERRORS
_const(INVALID_ENUM) is generated if __target is not one of the allowable
values.
.P
_const(INVALID_ENUM) is generated if __format is not one of the allowable
values.
.P
_const(INVALID_ENUM) is generated if __type is not one of the allowable
values.
.P
_const(INVALID_OPERATION) is generated if _cmnd is executed
between the execution of _cmnd(Begin) and the corresponding
execution of _cmnd(End).
.P
_const(INVALID_OPERATION) is generated if _param3 is one of
_const(UNSIGNED_BYTE_3_3_2),
_const(UNSIGNED_BYTE_2_3_3_REV),
_const(UNSIGNED_SHORT_5_6_5), or
_const(UNSIGNED_SHORT_5_6_5_REV)
and _param2 is not _const(RGB).
.P
_const(INVALID_OPERATION) is generated if _param3 is one of
_const(UNSIGNED_SHORT_4_4_4_4),
_const(UNSIGNED_SHORT_4_4_4_4_REV),
_const(UNSIGNED_SHORT_5_5_5_1),
_const(UNSIGNED_SHORT_1_5_5_5_REV),
_const(UNSIGNED_INT_8_8_8_8),
_const(UNSIGNED_INT_8_8_8_8_REV),
_const(UNSIGNED_INT_10_10_10_2), or
_const(UNSIGNED_INT_2_10_10_10_REV)
and _param2 is neither _const(RGBA) nor _const(BGRA).
.SH ASSOCIATED GETS
_cmnd(GetConvolutionParameter)
.SH SEE ALSO
_cmnd(GetSeparableFilter),
_cmnd(ConvolutionParameter),
_cmnd(ConvolutionFilter1D),
_cmnd(ConvolutionFilter2D)