1991-2006
Silicon Graphics, Inc.
glGetHistogramParameter
3G

# glGetHistogramParameter

get histogram parameters

## C Specification

                    void glGetHistogramParameterfv
                    GLenum target
                    GLenum pname
                    GLfloat * params

                    void glGetHistogramParameteriv
                    GLenum target
                    GLenum pname
                    GLint * params

## Parameters

`target`

  Must be one of `GL_HISTOGRAM` or `GL_PROXY_HISTOGRAM`.

`pname`

  The name of the parameter to be retrieved. Must be one of `GL_HISTOGRAM_WIDTH`, `GL_HISTOGRAM_FORMAT`, `GL_HISTOGRAM_RED_SIZE`, `GL_HISTOGRAM_GREEN_SIZE`, `GL_HISTOGRAM_BLUE_SIZE`, `GL_HISTOGRAM_ALPHA_SIZE`, `GL_HISTOGRAM_LUMINANCE_SIZE`, or `GL_HISTOGRAM_SINK`.

`params`

  Pointer to storage for the returned values.

## Description

`glGetHistogramParameter` is used to query parameter values for the current histogram or for a proxy. The histogram state information may be queried by calling `glGetHistogramParameter` with a `target` of `GL_HISTOGRAM` (to obtain information for the current histogram table) or `GL_PROXY_HISTOGRAM` (to obtain information from the most recent proxy request) and one of the following values for the `pname` argument:

Parameter | Description
--- | ---
`GL_HISTOGRAM_WIDTH` | Histogram table width
`GL_HISTOGRAM_FORMAT` | Internal format
`GL_HISTOGRAM_RED_SIZE` | Red component counter size, in bits
`GL_HISTOGRAM_GREEN_SIZE` | Green component counter size, in bits
`GL_HISTOGRAM_BLUE_SIZE` | Blue component counter size, in bits
`GL_HISTOGRAM_ALPHA_SIZE` | Alpha component counter size, in bits
`GL_HISTOGRAM_LUMINANCE_SIZE` | Luminance component counter size, in bits
`GL_HISTOGRAM_SINK` | Value of the sink parameter

## Notes

`glGetHistogramParameter` is present only if `ARB_imaging` is returned when glGetString is called with an argument of `GL_EXTENSIONS`.

## Errors

`GL_INVALID_ENUM` is generated if `target` is not one of the allowable values.

`GL_INVALID_ENUM` is generated if `pname` is not one of the allowable values.

`GL_INVALID_OPERATION` is generated if `glGetHistogramParameter` is executed between the execution of glBegin and the corresponding execution of glEnd.

## See Also

glGetHistogram, glHistogram

## 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/.