GLenum pnam )
void GLAPIENTRY glGetLightiv( GLenum light,
GLenum pnam )
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.
pnam 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.
_param3
Returns the requested data.
DESCRIPTION
glGetLight returns in _param3 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 implemen‐
tation dependent constant that is greater than or equal to eight. pnam
specifies one of ten light source parameters, again by symbolic name.
The following parameters are defined:
GL_AMBIENT _param3 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 repre‐
sentation 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 _param3 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 repre‐
sentation 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 _param3 returns four integer or floating-point val‐
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 _param3 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 nor‐
malized 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 _param3 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 _param3 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 repre‐
sentation to the nearest integer. The initial value
is 180.
GL_CONSTANT_ATTENUATION
_param3 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 internal
floating-point representation to the nearest inte‐
ger. The initial value is 1.
GL_LINEAR_ATTENUATION
_param3 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 repre‐
sentation to the nearest integer. The initial value
is 0.
GL_QUADRATIC_ATTENUATION
GL_INVALID_OPERATION is generated if glGetLight is executed between the
execution of glBegin and the corresponding execution of glEnd.
SEE ALSO
glLight
GLGETLIGHT(3G)
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