Name
gl.GetLight -- return light source parameter values
Synopsis
paramsArray = gl.GetLight(light, pname)
Function
gl.GetLight() returns in paramsArray the value or values of a light source parameter. light names the light and is a symbolic name of the form #GL_LIGHTi where i ranges from 0 to the value of #GL_MAX_LIGHTS - 1. #GL_MAX_LIGHTS is an implementation 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
Returns four floating-point values representing the ambient intensity of the light source. The initial value is (0, 0, 0, 1).

#GL_DIFFUSE
Returns four floating-point values representing the diffuse intensity of the light source. The initial value for #GL_LIGHT0 is (1, 1, 1, 1); for other lights, the initial value is (0, 0, 0, 0).

#GL_SPECULAR
Returns four floating-point values representing the specular intensity of the light source. The initial value for #GL_LIGHT0 is (1, 1, 1, 1); for other lights, the initial value is (0, 0, 0, 0).

#GL_POSITION
Returns four floating-point values representing the position of the light source. The returned values are those maintained in eye coordinates. They will not be equal to the values specified using gl.Light(), unless the modelview matrix was identity at the time gl.Light() was called. The initial value is (0, 0, 1, 0).

#GL_SPOT_DIRECTION
Returns three floating-point values representing the direction of the light source. The returned values are those maintained in eye coordinates. They will not be equal to the values specified using gl.Light(), unless the modelview matrix was identity at the time gl.Light() 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).

#GL_SPOT_EXPONENT
Returns a single floating-point value representing the spot exponent of the light. The initial value is 0.

#GL_SPOT_CUTOFF
Returns a single floating-point value representing the spot cutoff angle of the light. The initial value is 180.

#GL_CONSTANT_ATTENUATION
Returns a single floating-point value representing the constant (not distance-related) attenuation of the light. The initial value is 1.

#GL_LINEAR_ATTENUATION
Returns a single floating-point value representing the linear attenuation of the light. The initial value is 0.

#GL_QUADRATIC_ATTENUATION
Returns a single floating-point value representing the quadratic attenuation of the light. The initial value is 0.

It is always the case that #GL_LIGHT i = #GL_LIGHT0 + i.

Please consult an OpenGL reference manual for more information.

Inputs
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 i ranges from 0 to the value of #GL_MAX_LIGHTS - 1
pname
specifies a light source parameter for light (see above for possible parameters)
Results
paramsArray
table containing requested data
Errors
#GL_INVALID_ENUM is generated if light or pname is not an accepted value.

#GL_INVALID_OPERATION is generated if gl.GetLight() is executed between the execution of gl.Begin() and the corresponding execution of gl.End() .


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