glGetConvolutionFilterEXT(3G) OpenGL Reference glGetConvolutionFilterEXT(3G)
NAME
glGetConvolutionFilterEXT - get current 1D or 2D convolution filter
kernel
C SPECIFICATION
void glGetConvolutionFilterEXT( GLenum target,
GLenum format,
GLenum type,
GLvoid *image )
PARAMETERS
target The filter to be retrieved. Must be one of GLCONVOLUTION1DEXT
or GLCONVOLUTION2DEXT.
format Format of the output image. Must be one of GLRED, GLGREEN,
GLBLUE, GLALPHA, GLRGB, GLRGBA, GLABGREXT, GLLUMINANCE, or
GLLUMINANCEALPHA.
type Data type of components in the output image. Must be one of
GLUNSIGNEDBYTE, GLBYTE, GLUNSIGNEDSHORT, GLSHORT,
GLUNSIGNEDINT, GLINT, GLFLOAT, GLUNSIGNEDBYTE332EXT,
GLUNSIGNEDSHORT4444EXT, GLUNSIGNEDSHORT5551EXT,
GLUNSIGNEDINT8888EXT, or GLUNSIGNEDINT1010102EXT.
image Pointer to storage for the output image.
DESCRIPTION
glGetConvolutionFilterEXT returns the current 1D or 2D convolution filter
kernel as an image. The one- or two-dimensional image is placed in image
according to the specifications in format and type. No pixel transfer
operations are performed on this image, 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
NOTES
The current separable 2D filter must be retrieved with
glGetSeparableFilterEXT rather than glGetConvolutionFilterEXT.
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glGetConvolutionFilterEXT(3G) OpenGL Reference glGetConvolutionFilterEXT(3G)
ERRORS
GLINVALIDENUM is generated if target is not one of the allowable
values.
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 glGetConvolutionFilterEXT 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.
SEE ALSO
glGetSeparableFilterEXT, glConvolutionParameterEXT,
glConvolutionFilter1DEXT, glConvolutionFilter2DEXT.
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