glGetSeparableFilterEXT

NAME

glGetSeparableFilterEXT - get separable convolution filter kernel images

C SPECIFICATION

void glGetSeparableFilterEXT(GLenum target,
                               GLenum format,
                               GLenum type,
                               GLvoid *row,
                               GLvoid *column,
                               GLvoid *span)

PARAMETERS

target	The filter to be retrieved. Must be one of GL_SEPARABLE_2D_EXT.
format	The format of the returned pixel data. The allowable values are GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_LUMINANCE, GL_LUMINANCE_ALPHA, GL_RGB, GL_RGBA, GL_BGR_EXT, GL_BGRA_EXT, GL_422_EXT, GL_422_REV_EXT, GL_422_AVERAGE_EXT, and GL_422_REV_AVERAGE_EXT.
type	Specifies the data type for pixel data. The allowable values are GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2_EXT, GL_UNSIGNED_BYTE_2_3_3_REV_EXT, GL_UNSIGNED_SHORT_5_6_5_EXT, GL_UNSIGNED_SHORT_5_6_5_REV_EXT, GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_4_4_4_4_REV_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT, GL_UNSIGNED_SHORT_1_5_5_5_REV_EXT, GL_UNSIGNED_INT_8_8_8_8_EXT, GL_UNSIGNED_INT_8_8_8_8_REV_EXT, GL_UNSIGNED_INT_10_10_10_2_EXT, and GL_UNSIGNED_INT_2_10_10_10_REV_EXT.
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.

DESCRIPTION

glGetSeparableFilterEXT 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. The span parameter is currently unused. 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 format of the filter 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

Internal Component	Resulting Component
Red	Red
Green	Green
Blue	Blue
Alpha	Alpha
Luminance	Red
Intensity	Red

NOTES

The current convolution 2D filter must be retrieved with glGetConvolutionFilterEXT rather than glGetSeparableFilterEXT.

The span parameter is reserved for possible future use by separable 3D filters.

EXTENSIONS

Some routines and constants for this function are part of an extension, not part of the core GL command set. The following extension names must be present in the string returned by glGetString when called with argument GL_EXTENSIONS to use these routines and constants.

GL_EXT_422_pixels: GL_422_EXT, GL_422_REV_EXT, GL_422_AVERAGE_EXT, and GL_422_REV_AVERAGE_EXT are part of the EXT_422_pixels extension.
GL_EXT_bgra: GL_BGR_EXT and GL_BGRA_EXT are part of the EXT_bgra extension.
GL_EXT_convolution: glGetSeparableFilterEXT and GL_SEPARABLE_2D_EXT are part of the EXT_convolution extension.
GL_EXT_packed_pixels: GL_UNSIGNED_BYTE_3_3_2_EXT, GL_UNSIGNED_BYTE_2_3_3_REV_EXT, GL_UNSIGNED_SHORT_5_6_5_EXT, GL_UNSIGNED_SHORT_5_6_5_REV_EXT, GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_4_4_4_4_REV_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT, GL_UNSIGNED_SHORT_1_5_5_5_REV_EXT, GL_UNSIGNED_INT_8_8_8_8_EXT, GL_UNSIGNED_INT_8_8_8_8_REV_EXT, GL_UNSIGNED_INT_10_10_10_2_EXT, and GL_UNSIGNED_INT_2_10_10_10_REV_EXT are part of the EXT_packed_pixels extension.

ERRORS

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

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 glGetSeparableFilterEXT is executed between the execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS

glGetConvolutionParameterEXT