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GLGETLIGHT(3G)							GLGETLIGHT(3G)

NAME
       glGetLightfv, glGetLightiv - 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 0 ≤ i < GL_MAX_LIGHTS.

       pname   Specifies a light source parameter for  light.	Accepted  sym‐
	       bolic	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 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:

       GL_AMBIENT	   params  returns four integer or floating-point val‐
			   ues representing the ambient intensity of the light
			   source.   Integer  values, when requested, are lin‐
			   early mapped from the internal floating-point  rep‐
			   resentation 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  val‐
			   ues representing the diffuse intensity of the light
			   source.  Integer values, when requested,  are  lin‐
			   early  mapped from the internal floating-point rep‐
			   resentation 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 val‐
			   ues 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 posi‐
			   tive 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 unde‐
			   fined. 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  val‐
			   ues	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 val‐
			   ues 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  normal‐
			   ization. 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 com‐
			   puted by rounding the internal floating-point  rep‐
			   resentation	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 near‐
			   est 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 com‐
			   puted by rounding the internal floating-point  rep‐
			   resentation	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  com‐
			   puted  by rounding the internal floating-point rep‐
			   resentation 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(3G)

								GLGETLIGHT(3G)
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