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 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 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.

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 values.

GL_INVALID_ENUM is generated if type is not one of the allowable values.

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 format is neither GL_RGBA nor GL_BGRA.

ASSOCIATED GETS
glGetConvolutionParameter

SEE ALSO
glGetConvolutionFilter, glConvolutionParameter, glSeparableFilter2D