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<STRONG>NAME</STRONG>
<STRONG>glGetLightfv,</STRONG> <STRONG>glGetLightiv</STRONG> - return light source parameter
values
<STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>
void <STRONG>glGetLightfv</STRONG>( GLenum <EM>light</EM>,
GLenum <EM>pname</EM>,
GLfloat *<EM>params</EM> )
void <STRONG>glGetLightiv</STRONG>( GLenum <EM>light</EM>,
GLenum <EM>pname</EM>,
GLint *<EM>params</EM> )
<STRONG>PARAMETERS</STRONG>
<EM>light</EM> 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 <STRONG>GL_LIGHT</STRONG>i where 0 <EM><</EM> i <
<STRONG>GL_MAX_LIGHTS</STRONG>.
<EM>pname</EM> Specifies a light source parameter for <EM>light</EM>.
Accepted symbolic names are <STRONG>GL_AMBIENT</STRONG>, <STRONG>GL_DIFFUSE</STRONG>,
<STRONG>GL_SPECULAR</STRONG>, <STRONG>GL_POSITION</STRONG>, <STRONG>GL_SPOT_DIRECTION</STRONG>,
<STRONG>GL_SPOT_EXPONENT</STRONG>, <STRONG>GL_SPOT_CUTOFF</STRONG>,
<STRONG>GL_CONSTANT_ATTENUATION</STRONG>, <STRONG>GL_LINEAR_ATTENUATION</STRONG> , and
<STRONG>GL_QUADRATIC_ATTENUATION</STRONG>.
<EM>params</EM> Returns the requested data.
<STRONG>DESCRIPTION</STRONG>
<STRONG>glGetLight</STRONG> returns in <EM>params</EM> the value or values of a light
source parameter. <EM>light</EM> names the light and is a symbolic
name of the form <STRONG>GL_LIGHT</STRONG>i for 0<EM><</EM>i<<STRONG>GL_MAX_LIGHTS</STRONG>, where
<STRONG>GL_MAX_LIGHTS</STRONG> is an implementation dependent constant that
is greater than or equal to eight. <EM>pname</EM> specifies one of
ten light source parameters, again by symbolic name.
The following parameters are defined:
<STRONG>GL_AMBIENT</STRONG> <EM>params</EM> 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).
<STRONG>GL_DIFFUSE</STRONG> <EM>params</EM> 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
<STRONG>GL_LIGHT0</STRONG> is (1, 1, 1, 1); for other
lights, the initial value is (0, 0, 0,
0).
<STRONG>GL_SPECULAR</STRONG> <EM>params</EM> 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
<STRONG>GL_LIGHT0</STRONG> is (1, 1, 1, 1); for other
lights, the initial value is (0, 0, 0,
0).
<STRONG>GL_POSITION</STRONG> <EM>params</EM> 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
<STRONG>glLight</STRONG>, unless the modelview matrix was
identity at the time <STRONG>glLight</STRONG> was called.
The initial value is (0, 0, 1, 0).
<STRONG>GL_SPOT_DIRECTION</STRONG> <EM>params</EM> 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
<STRONG>glLight</STRONG>, unless the modelview matrix was
identity at the time <STRONG>glLight</STRONG> 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).
<STRONG>GL_SPOT_EXPONENT</STRONG> <EM>params</EM> 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.
<STRONG>GL_SPOT_CUTOFF</STRONG> <EM>params</EM> 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.
<STRONG>GL_CONSTANT_ATTENUATION</STRONG>
<EM>params</EM> 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.
<STRONG>GL_LINEAR_ATTENUATION</STRONG>
<EM>params</EM> 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.
<STRONG>GL_QUADRATIC_ATTENUATION</STRONG>
<EM>params</EM> 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.
<STRONG>NOTES</STRONG>
It is always the case that <STRONG>GL_LIGHT</STRONG>i = <STRONG>GL_LIGHT0</STRONG> + i.
If an error is generated, no change is made to the contents
of <EM>params</EM>.
<STRONG>ERRORS</STRONG>
<STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>light</EM> or <EM>pname</EM> is not an
accepted value.
<STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>glGetLight</STRONG> is executed
between the execution of <STRONG>glBegin</STRONG> and the corresponding
execution of <STRONG>glEnd</STRONG>.
<STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>
<STRONG>glLight</STRONG>
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