glGetHistogramParameter

Name

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.