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GLGETLIGHT(3G)			 OpenGL Manual			GLGETLIGHT(3G)

NAME
       glGetLight - return light source parameter values

C SPECIFICATION
       void glGetLightfv(GLenum light, GLenum pname, GLfloat * params);

       void glGetLightiv(GLenum light, GLenum pname, GLint * params);

PARAMETERS
       light
	   Specifies a light source. The number of possible lights depends on
	   the implementation, but at least eight lights are supported. They
	   are identified by symbolic names of the form GL_LIGHTi where i
	   ranges from 0 to the value of GL_MAX_LIGHTS - 1.

       pname
	   Specifies a light source parameter for light. Accepted symbolic
	   names are GL_AMBIENT, GL_DIFFUSE, GL_SPECULAR, GL_POSITION,
	   GL_SPOT_DIRECTION, GL_SPOT_EXPONENT, GL_SPOT_CUTOFF,
	   GL_CONSTANT_ATTENUATION, GL_LINEAR_ATTENUATION, and
	   GL_QUADRATIC_ATTENUATION.

       params
	   Returns the requested data.

DESCRIPTION
       glGetLight returns in params the value or values of a light source
       parameter.  light names the light and is a symbolic name of the form
       GL_LIGHTi where i ranges from 0 to the value of GL_MAX_LIGHTS - 1.
       GL_MAX_LIGHTS is an implementation dependent constant that is greater
       than or equal to eight.	pname specifies one of ten light source
       parameters, again by symbolic name.

       The following parameters are defined:

       GL_AMBIENT
	   params returns four integer or floating-point values representing
	   the ambient intensity of the light source. Integer values, when
	   requested, are linearly mapped from the internal floating-point
	   representation such that 1.0 maps to the most positive
	   representable integer value, and -1.0 maps to the most negative
	   representable integer value. If the internal value is outside the
	   range -1 1, the corresponding integer return value is undefined.
	   The initial value is (0, 0, 0, 1).

       GL_DIFFUSE
	   params returns four integer or floating-point values representing
	   the diffuse intensity of the light source. Integer values, when
	   requested, are linearly mapped from the internal floating-point
	   representation such that 1.0 maps to the most positive
	   representable integer value, and -1.0 maps to the most negative
	   representable integer value. If the internal value is outside the
	   range -1 1, the corresponding integer return value is undefined.
	   The initial value for GL_LIGHT0 is (1, 1, 1, 1); for other lights,
	   the initial value is (0, 0, 0, 0).

       GL_SPECULAR
	   params returns four integer or floating-point values representing
	   the specular intensity of the light source. Integer values, when
	   requested, are linearly mapped from the internal floating-point
	   representation such that 1.0 maps to the most positive
	   representable integer value, and -1.0 maps to the most negative
	   representable integer value. If the internal value is outside the
	   range -1 1, the corresponding integer return value is undefined.
	   The initial value for GL_LIGHT0 is (1, 1, 1, 1); for other lights,
	   the initial value is (0, 0, 0, 0).

       GL_POSITION
	   params returns four integer or floating-point values representing
	   the position of the light source. Integer values, when requested,
	   are computed by rounding the internal floating-point values to the
	   nearest integer value. The returned values are those maintained in
	   eye coordinates. They will not be equal to the values specified
	   using glLight(), unless the modelview matrix was identity at the
	   time glLight() was called. The initial value is (0, 0, 1, 0).

       GL_SPOT_DIRECTION
	   params returns three integer or floating-point values representing
	   the direction of the light source. Integer values, when requested,
	   are computed by rounding the internal floating-point values to the
	   nearest integer value. The returned values are those maintained in
	   eye coordinates. They will not be equal to the values specified
	   using glLight(), unless the modelview matrix was identity at the
	   time glLight() was called. Although spot direction is normalized
	   before being used in the lighting equation, the returned values are
	   the transformed versions of the specified values prior to
	   normalization. The initial value is 0 0 -1.

       GL_SPOT_EXPONENT
	   params returns a single integer or floating-point value
	   representing the spot exponent of the light. An integer value, when
	   requested, is computed by rounding the internal floating-point
	   representation to the nearest integer. The initial value is 0.

       GL_SPOT_CUTOFF
	   params returns a single integer or floating-point value
	   representing the spot cutoff angle of the light. An integer value,
	   when requested, is computed by rounding the internal floating-point
	   representation to the nearest integer. The initial value is 180.

       GL_CONSTANT_ATTENUATION
	   params returns a single integer or floating-point value
	   representing the constant (not distance-related) attenuation of the
	   light. An integer value, when requested, is computed by rounding
	   the internal floating-point representation to the nearest integer.
	   The initial value is 1.

       GL_LINEAR_ATTENUATION
	   params returns a single integer or floating-point value
	   representing the linear attenuation of the light. An integer value,
	   when requested, is computed by rounding the internal floating-point
	   representation to the nearest integer. The initial value is 0.

       GL_QUADRATIC_ATTENUATION
	   params returns a single integer or floating-point value
	   representing the quadratic attenuation of the light. An integer
	   value, when requested, is computed by rounding the internal
	   floating-point representation to the nearest integer. The initial
	   value is 0.

NOTES
       It is always the case that GL_LIGHTi = GL_LIGHT0 + i.

       If an error is generated, no change is made to the contents of params.

ERRORS
       GL_INVALID_ENUM is generated if light or pname is not an accepted
       value.

       GL_INVALID_OPERATION is generated if glGetLight is executed between the
       execution of glBegin() and the corresponding execution of glEnd().

SEE ALSO
       glLight()

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/.

AUTHORS
       opengl.org

opengl.org			  04/29/2014			GLGETLIGHT(3G)

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