C SPECIFICATION

       void GLAPIENTRY glConvolutionParameterf( GLenum target,
                                                GLenum pnam )
       void GLAPIENTRY glConvolutionParameteri( GLenum target,
                                                GLenum pnam )

PARAMETERS

       target  The target for the  convolution  parameter.   Must  be  one  of
               GL_CONVOLUTION_1D, GL_CONVOLUTION_2D, or GL_SEPARABLE_2D.

       pnam    The parameter to be set.  Must be GL_CONVOLUTION_BORDER_MODE.

       _param3(1)
               The    parameter    value.    Must   be   one   of   GL_REDUCE,
               GL_CONSTANT_BORDER, GL_REPLICATE_BORDER.

C SPECIFICATION

       void GLAPIENTRY glConvolutionParameterfv( GLenum target,
                                                 GLenum pnam )
       void GLAPIENTRY glConvolutionParameteriv( GLenum target,
                                                 GLenum pnam )

PARAMETERS

       target The target for  the  convolution  parameter.   Must  be  one  of
              GL_CONVOLUTION_1D, GL_CONVOLUTION_2D, or GL_SEPARABLE_2D.

       pnam   The    parameter    to    be    set.     Must    be    one    of
              GL_CONVOLUTION_BORDER_MODE,         GL_CONVOLUTION_BORDER_COLOR,
              GL_CONVOLUTION_FILTER_SCALE, or GL_CONVOLUTION_FILTER_BIAS.

       _param3(2)
              The  parameter  value.   If  pnam is GL_CONVOLUTION_BORDER_MODE,
              _param3(2) must be  one  of  GL_REDUCE,  GL_CONSTANT_BORDER,  or
              GL_REPLICATE_BORDER.  Otherwise, must be a vector of four values
              (for red, green, blue, and alpha, respectively) to be  used  for
              scaling  (when  pnam is GL_CONVOLUTION_FILTER_SCALE), or biasing
              (when pnam is GL_CONVOLUTION_FILTER_BIAS) a  convolution  filter
              kernel  or  setting  the  constant  border  color  (when pnam is
              GL_CONVOLUTION_BORDER_COLOR.

DESCRIPTION

       glConvolutionParameter sets the value of a convolution parameter.

       target   selects   the   convolution    filter    to    be    affected:
       GL_CONVOLUTION_1D,  GL_CONVOLUTION_2D,  or  GL_SEPARABLE_2D for the 1D,
       2D, or separable 2D filter, respectively.

       pnam selects the parameter to be changed.   GL_CONVOLUTION_FILTER_SCALE
              source image width is Ws and height is Hs,  then  the  convolved
              image  width  will  be  Ws-Wf+1 and height will be Hs-Hf+1.  (If
              this reduction would generate an image  with  zero  or  negative
              width  and/or  height,  the output is simply null, with no error
              generated.)  The coordinates of the image resulting from  convo-
              lution are zero through Ws-Wf in width and zero through Hs-Hf in
              height.

       GL_CONSTANT_BORDER
              The image resulting from convolution is the  same  size  as  the
              source  image,  and  processed  as if the source image were sur-
              rounded  by  pixels  with   their   color   specified   by   the
              GL_CONVOLUTION_BORDER_COLOR.

       GL_REPLICATE_BORDER
              The  image  resulting  from  convolution is the same size as the
              source image, and processed as if the  outermost  pixel  on  the
              border of the source image were replicated.

NOTES

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

       In cases where errors can result  from  the  specification  of  invalid
       image  dimensions,  it  is  the  dimensions  after convolution that are
       tested,  not  the  dimensions  of  the  source  image.   For   example,
       glTexImage1D  requires  power-of-two image size.  When GL_REDUCE border
       mode is in effect, the source image  must  be  larger  than  the  final
       power-of-two size by one less than the size of the 1D filter kernel.

ERRORS

       GL_INVALID_ENUM is generated if target is not one of the allowable val-
       ues.

       GL_INVALID_ENUM is generated if pnam is not one of the  allowable  val-
       ues.

       GL_INVALID_ENUM  is generated if pnam is GL_CONVOLUTION_BORDER_MODE and
       _param3(1)  is   not   one   of   GL_REDUCE,   GL_CONSTANT_BORDER,   or
       GL_REPLICATE_BORDER.

       GL_INVALID_OPERATION is generated if glConvolutionParameter is executed
       between the execution of glBegin and  the  corresponding  execution  of
       glEnd.

ASSOCIATED GETS

       glGetConvolutionParameter

SEE ALSO

       glConvolutionFilter1D,    glConvolutionFilter2D,   glSeparableFilter2D,
       glGetConvolutionParameter