glGetSeparableFilterEXT(3G) OpenGL Reference glGetSeparableFilterEXT(3G)
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 separable filter to be retrieved. Must be
GLSEPARABLE2DEXT.
format Format of the output images. Must be one of GLRED, GLGREEN,
GLBLUE, GLALPHA, GLRGB, GLRGBA, GLABGREXT, GLLUMINANCE, or
GLLUMINANCEALPHA.
type Data type of components in the output images. Must be one of
GLUNSIGNEDBYTE, GLBYTE, GLUNSIGNEDSHORT, GLSHORT,
GLUNSIGNEDINT, GLINT, GLFLOAT, GLUNSIGNEDBYTE332EXT,
GLUNSIGNEDSHORT4444EXT, GLUNSIGNEDSHORT5551EXT,
GLUNSIGNEDINT8888EXT, or GLUNSIGNEDINT1010102EXT.
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. (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 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
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glGetSeparableFilterEXT(3G) OpenGL Reference glGetSeparableFilterEXT(3G)
alpha alpha
luminance red
intensity red
NOTES
Non-separable 2D filters must be retrieved with
glGetConvolutionFilterEXT.
The span argument is reserved for possible future use by separable 3D
filters.
ERRORS
GLINVALIDENUM is generated if target is not GLSEPARABLE2DEXT.
GLINVALIDENUM is generated if format is not one of the allowable
values.
GLINVALIDENUM is generated if type is not one of the allowable values.
GLINVALIDOPERATION is generated if glGetSeparableFilterEXT is executed
between the execution of glBegin and the corresponding execution of
glEnd.
If type is set to GLUNSIGNEDBYTE332EXT,
GLUNSIGNEDSHORT4444EXT, GLUNSIGNEDSHORT5551EXT,
GLUNSIGNEDINT8888EXT, or GLUNSIGNEDINT1010102EXT and the
EXTpackedpixels extension is not supported then a GLINVALIDENUM error
is generated.
ASSOCIATED GETS
glGetConvolutionParameterEXT
MACHINE DEPENDENCIES
On RealityEngine, RealityEngine2, and VTX systems convolution may not be
used in the following circumstances:
1. When rendering to pixmaps.
2. When fragment processing (texturing, depth buffering, alpha
testing, multisampling, fog) is enabled.
3. When histogramming or minmax is enabled.
4. When either of the pixel zoom factors has a value other than 1.0
or -1.0.
In these cases, glDrawPixels and glCopyPixels report a
GLINVALIDOPERATION error and do not transfer any pixels.
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glGetSeparableFilterEXT(3G) OpenGL Reference glGetSeparableFilterEXT(3G)
SEE ALSO
glGetConvolutionFilterEXT, glConvolutionParameterEXT,
glSeparableFilter2DEXT.
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