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.

If a non-zero named buffer object is bound to the GL_PIXEL_PACK_BUFFER target (see glBindBuffer()) while a separable convolution filter is requested, row, column, and span are treated as a byte offset into the buffer object's data store.

Color components that are present in format but not included in the internal format 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 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 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.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_PACK_BUFFER target and the buffer object's data store is currently mapped.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_PACK_BUFFER target and the data would be packed to the buffer object such that the memory writes required would exceed the data store size.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_PACK_BUFFER target and row or column is not evenly divisible into the number of bytes needed to store in memory a datum indicated by type.

GL_INVALID_OPERATION is generated if glGetSeparableFilter is executed between the execution of glBegin() and the corresponding execution of glEnd().

ASSOCIATED GETS

glGetConvolutionParameter()

glGet() with argument GL_PIXEL_PACK_BUFFER_BINDING

SEE ALSO

glGetConvolutionFilter(), glConvolutionParameter(), glSeparableFilter2D()

COPYRIGHT

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.