glGetConvolutionFilter

glGetConvolutionFilter: man2/glGetConvolutionFilter.xml

glGetConvolutionFilter 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. If a non-zero named buffer object is bound to the GL_PIXEL_PACK_BUFFER target (see glBindBuffer ) while a convolution filter is requested, image is 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 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

glGetConvolutionFilter is present only if ARB_imaging is returned when glGetString is called with an argument of GL_EXTENSIONS. The current separable 2D filter must be retrieved with glGetSeparableFilter rather than glGetConvolutionFilter.