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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 (C) 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				    06/10/2014				   GLGETLIGHT(3G)
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