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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 de-
               pends on the implementation, but at least eight lights are sup-
               ported.   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  pa-
       rameter.   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, un-
                           less  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, un-
                           less the modelview matrix was identity at the  time
                           glLight  was  called.   Although  spot direction is
                           normalized before being used in the lighting  equa-
                           tion,  the returned values are the transformed ver-
                           sions of the specified values prior  to  normaliza-
                           tion. 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-re-
                           lated) attenuation of the light.  An integer value,
                           when  requested, is computed by rounding the inter-
                           nal 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 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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