glGetLightiv man page on Tru64

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glGetLight(3G)							glGetLight(3G)

NAME
       glGetLight,  glGetLightfv, glGetLightiv - return light source parameter
       values

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

PARAMETERS
       Specifies a light source. The number of possible lights depends on  the
       implementation, but at least eight lights are supported. They are iden‐
       tified by symbolic names	 of  the  form	GL_LIGHTi  where  0  <=	 i   <
       GL_MAX_LIGHTS.	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_ATTEN‐
       UATION, GL_LINEAR_ATTENUATION, and  GL_QUADRATIC_ATTENUATION.   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  for 0 <= i < GL_MAX_LIGHTS, where GL_MAX_LIGHTS is an imple‐
       mentation 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: 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	 nega‐
       tive  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).	 params returns four integer or float‐
       ing-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 nega‐
       tive 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 ini‐
       tial  value  is (0, 0, 0, 0).  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 repre‐
       sentable 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).	 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).
       params returns three integer or floating-point values representing  the
       direction of the light source. Integer values, when requested, are com‐
       puted by rounding the internal floating-point  values  to  the  nearest
       integer value.  The returned values are those maintained in eye coordi‐
       nates. 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).	params returns a single integer or floating-point value repre‐
       senting the  spot  exponent  of	the  light.  An	 integer  value,  when
       requested,  is  computed by rounding the internal floating-point repre‐
       sentation to the nearest integer.  The  initial	value  is  0.	params
       returns	a single integer or floating-point value representing the spot
       cutoff angle of the light. An integer value, when  requested,  is  com‐
       puted  by  rounding  the	 internal floating-point representation to the
       nearest integer.	 The initial value is 180.  params  returns  a	single
       integer	or  floating-point  value  representing the constant (not dis‐
       tance-related)  attenuation  of	the  light.  An	 integer  value,  when
       requested,  is  computed by rounding the internal floating-point repre‐
       sentation to the nearest integer.  The  initial	value  is  1.	params
       returns	a single integer or floating-point value representing the lin‐
       ear attenuation of the light. An integer value, when requested, is com‐
       puted  by  rounding  the	 internal floating-point representation to the
       nearest integer. The initial value is 0.	 params returns a single inte‐
       ger  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(3)

								glGetLight(3G)
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