NAME

glGetLightfv, glGetLightiv - return light source parameter values

C SPECIFICATION

void ggllGGeettLLiigghhttffvv( GLenum _l_i_g_h_t,
                   GLenum _p_n_a_m_e,
                   GLfloat _*_p_a_r_a_m_s )
void ggllGGeettLLiigghhttiivv( GLenum _l_i_g_h_t,
                   GLenum _p_n_a_m_e,
                   GLint _*_p_a_r_a_m_s )

delim $$

PARAMETERS

_l_i_g_h_t
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 GGLL__LLIIGGHHTT$i$ where 0 <= $ i $ < GGLL__MMAAXX__LLIIGGHHTTSS.
_p_n_a_m_e
Specifies a light source parameter for _l_i_g_h_t. Accepted symbolic names are GGLL__AAMMBBIIEENNTT, GGLL__DDIIFFFFUUSSEE, GGLL__SSPPEECCUULLAARR, GGLL__PPOOSSIITTIIOONN, GGLL__SSPPOOTT__DDIIRREECCTTIIOONN, GGLL__SSPPOOTT__EEXXPPOONNEENNTT, GGLL__SSPPOOTT__CCUUTTOOFFFF, GGLL__CCOONNSSTTAANNTT__AATTTTEENNUUAATTIIOONN, GGLL__LLIINNEEAARR__AATTTTEENNUUAATTIIOONN, and GGLL__QQUUAADDRRAATTIICC__AATTTTEENNUUAATTIIOONN.
_p_a_r_a_m_s
Returns the requested data.

DESCRIPTION

ggllGGeettLLiigghhtt returns in _p_a_r_a_m_s the value or values of a light source parameter. _l_i_g_h_t names the light and is a symbolic name of the form GGLL__LLIIGGHHTT$i$ for 0 <= $i$ < GGLL__MMAAXX__LLIIGGHHTTSS, where GGLL__MMAAXX__LLIIGGHHTTSS is an implementation dependent constant that is greater than or equal to eight. _p_n_a_m_e specifies one of ten light source parameters, again by symbolic name.

The following parameters are defined:

GGLL__AAMMBBIIEENNTT
_p_a_r_a_m_s 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).
GGLL__DDIIFFFFUUSSEE
_p_a_r_a_m_s 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 GGLL__LLIIGGHHTT00 is (1, 1, 1, 1); for other lights, the initial value is (0, 0, 0, 0).
GGLL__SSPPEECCUULLAARR
_p_a_r_a_m_s 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 GGLL__LLIIGGHHTT00 is (1, 1, 1, 1); for other lights, the initial value is (0, 0, 0, 0).
GGLL__PPOOSSIITTIIOONN
_p_a_r_a_m_s 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 ggllLLiigghhtt, unless the modelview matrix was identity at the time ggllLLiigghhtt was called. The initial value is (0, 0, 1, 0).
GGLL__SSPPOOTT__DDIIRREECCTTIIOONN
_p_a_r_a_m_s 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 ggllLLiigghhtt, unless the modelview matrix was identity at the time ggllLLiigghhtt 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).
GGLL__SSPPOOTT__EEXXPPOONNEENNTT
_p_a_r_a_m_s 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.
GGLL__SSPPOOTT__CCUUTTOOFFFF
_p_a_r_a_m_s 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.
GGLL__CCOONNSSTTAANNTT__AATTTTEENNUUAATTIIOONN
_p_a_r_a_m_s 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.
GGLL__LLIINNEEAARR__AATTTTEENNUUAATTIIOONN
_p_a_r_a_m_s 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.
GGLL__QQUUAADDRRAATTIICC__AATTTTEENNUUAATTIIOONN
_p_a_r_a_m_s 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 GGLL__LLIIGGHHTT$i$ = GGLL__LLIIGGHHTT00 + $i$.

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

ERRORS

GGLL__IINNVVAALLIIDD__EENNUUMM is generated if _l_i_g_h_t or _p_n_a_m_e is not an accepted value.

GGLL__IINNVVAALLIIDD__OOPPEERRAATTIIOONN is generated if ggllGGeettLLiigghhtt is executed between the execution of ggllBBeeggiinn and the corresponding execution of ggllEEnndd.

SEE ALSO

ggllLLiigghhtt((33GG))