glGetSeparableFilter(3)

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 GL_SEPARABLE_2D.

       format  Format of the output images.  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  images.   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.

       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 GL_ARB_imaging is returned when
       glGetString is called with an argument of GL_EXTENSIONS.

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

ERRORS

       GL_INVALID_ENUM is generated if target is not GL_SEPARABLE_2D.

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

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

       GL_INVALID_OPERATION is generated if glGetSeparableFilter  is  executed
       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

       glGetConvolutionFilter(3G),                 glConvolutionParameter(3G),
       glSeparableFilter2D(3G)

                                                      GLGETSEPARABLEFILTER(3G)