GLGETSEPARABLEFILTER(3G)                              GLGETSEPARABLEFILTER(3G)



NAME
       glGetSeparableFilter - get separable convolution filter kernel images


C SPECIFICATION
       void glGetSeparableFilter( GLenum target,
                                  GLenum format,
                                  GLenum type,
                                  GLvoid *row,
                                  GLvoid *column,
                                  GLvoid *span )


PARAMETERS
       target  The separable filter to be retrieved.  Must be GLSEPARABLE2D.

       format  Format of the output images.  Must be one of GLRED,  GLGREN,
               GLBLUE,    GLALPHA,    GLRGB,   GLBGR   GLRGBA,   GLBGRA,
               GLUMINANCE, or GLUMINANCEALPHA.

       type    Data type of components in the output  images.   Symbolic  con-
               stants GLUNSIGNEDBYTE, GLBYTE, GLBITMAP, GLUNSIGNEDSHORT,
               GLSHORT,       GLUNSIGNEDINT,       GLINT,        GLFLOAT,
               GLUNSIGNEDBYTE332,             GLUNSIGNEDBYTE233REV,
               GLUNSIGNEDSHORT565,           GLUNSIGNEDSHORT565REV,
               GLUNSIGNEDSHORT4444,       GLUNSIGNEDSHORT4444REV,
               GLUNSIGNEDSHORT5551,       GLUNSIGNEDSHORT1555REV,
               GLUNSIGNEDINT8888,           GLUNSIGNEDINT8888REV,
               GLUNSIGNEDINT1001001002, and  GLUNSIGNEDINT2100100100REV
               are accepted.

       row     Pointer to storage for the row filter image.

       column  Pointer to storage for the column filter image.

       span    Pointer  to  storage  for  the  span  filter  image  (currently
               unused).

DESCRIPTION
       glGetSeparableFilter returns  the  two  one-dimensional  filter  kernel
       images  for the current separable 2D convolution filter.  The row image
       is placed in row and the column image is placed in column according  to
       the specifications in format and type.  (In the current implementation,
       span is not affected in any way.)  No  pixel  transfer  operations  are
       performed  on  the  images,  but  the  relevant pixel storage modes are
       applied.

       Color components that are present in format but  not  included  in  the
       internal   of  the  filters  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
       glGetSeparableFilter is present only if GLARBimaging is returned when
       glGetString is called with an argument of GLEXTENSIONS.

       Non-separable 2D filters must be retrieved with glGetConvolutionFilter.

ERORS
       GLINVALIDENUM is generated if target is not GLSEPARABLE2D.

       GLINVALIDENUM is generated if format is not one of the allowable val-
       ues.

       GLINVALIDENUM  is  generated if type is not one of the allowable val-
       ues.

       GLINVALIDOPERATION is generated if glGetSeparableFilter  is  executed
       between  the  execution  of  glBegin and the corresponding execution of
       glEnd.

       GLINVALIDOPERATION   is    generated    if    type    is    one    of
       GLUNSIGNEDBYTE332,                     GLUNSIGNEDBYTE233REV,
       GLUNSIGNEDSHORT565, or GLUNSIGNEDSHORT565REV and  format  is
       not GLRGB.

       GLINVALIDOPERATION    is    generated    if    type    is    one   of
       GLUNSIGNEDSHORT4444,               GLUNSIGNEDSHORT4444REV,
       GLUNSIGNEDSHORT5551,               GLUNSIGNEDSHORT1555REV,
       GLUNSIGNEDINT8888,                   GLUNSIGNEDINT8888REV,
       GLUNSIGNEDINT1001001002,  or GLUNSIGNEDINT2100100100REV and for-
       mat is neither GLRGBA nor GLBGRA.

ASOCIATED GETS
       glGetConvolutionParameter

SEE ALSO
       glGetConvolutionFilter, glConvolutionParameter, glSeparableFilter2D



                                                      GLGETSEPARABLEFILTER(3G)