glGetHistogram returns the current histogram table as a one-dimensional image with the same width as the histogram. No pixel transfer operations are performed on this image, but pixel storage modes that are applicable to 1D images are honored. If a non-zero named buffer object is bound to the GL_PIXEL_PACK_BUFFER target (see glBindBuffer ) while a histogram table is requested, values is treated as a byte offset into the buffer object's data store. Color components that are requested in the specified format, but which are not included in the internal format of the histogram, are returned as zero. The assignments of internal color components to the components requested by format are: Internal ComponentResulting Component Red Red Green Green Blue Blue Alpha Alpha Luminance Red
glGetHistogram is present only if ARB_imaging is returned when glGetString is called with an argument of GL_EXTENSIONS.
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glGetHistogram: man2/glGetHistogram.xml
glGetHistogram returns the current histogram table as a one-dimensional image with the same width as the histogram. No pixel transfer operations are performed on this image, but pixel storage modes that are applicable to 1D images are honored. If a non-zero named buffer object is bound to the GL_PIXEL_PACK_BUFFER target (see glBindBuffer ) while a histogram table is requested, values is treated as a byte offset into the buffer object's data store. Color components that are requested in the specified format, but which are not included in the internal format of the histogram, are returned as zero. The assignments of internal color components to the components requested by format are: Internal Component Resulting Component Red Red Green Green Blue Blue Alpha Alpha Luminance Red
glGetHistogram is present only if ARB_imaging is returned when glGetString is called with an argument of GL_EXTENSIONS.