GLenum forma )

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

       forma   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.

       _param3 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.

       _param4 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
       _param4  according to the specifications in forma and _param3.  No pixel
       transfer operations are performed on this image, but the relevant  pixel
       storage modes are applied.

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

       GL_INVALID_OPERATION   is   generated   if    _param3    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 forma is not
       GL_RGB.

       GL_INVALID_OPERATION    is    generated    if    _param3   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 forma
       is neither GL_RGBA nor GL_BGRA.

ASSOCIATED GETS
       glGetConvolutionParameter

SEE ALSO
       glGetSeparableFilter,   glConvolutionParameter,   glConvolutionFilter1D,
       glConvolutionFilter2D

                                                     GLGETCONVOLUTIONFILTER(3G)