The SG_Light node defines a light source in a SG(3) scene-graph. Each light source is associated with a priority number, which determines which lights are used in the rendering. The number of lights supported for rendering is dependent on the renderer implementation.

AG_Object(3)-> SG_Node(3)-> SG_Light.

The SG_LightNew() function allocates, initializes, and attaches a SG_Light object.

The functions SG_LightAmbient(), SG_LightDiffuse() and SG_LightSpecular() configure the colors associated with the ambient, diffuse and specular components of the light source.

SG_LightSpot() sets the spot parameters of the light source. cutoff specifies the cutoff angle in degrees, exponent specifies the light intensity (the higher the exponent, the more focused the light source; a value of 0 provides uniform distribution), and dir is the direction vector. If the cutoff angle is < 180 degrees, the light source is directional, otherwise it is treated as a point source and the direction vector is ignored.

The SG_LightSetup() function sets up the renderer states associated with a light, prior to rendering. This function is usually invoked from the draw() operation of an SG_View(3) (or derived) widget, prior to rendering a scene.

For the SG_Light object:

int pri	Priority of light source when number of sources is limited (0 = highest priority).
M_Color ambient	Ambient color component of source.
M_Color diffuse	Diffuse color component of source.
M_Color specular	Specular color component of source.
M_Real spot_cutoff	Spotlight cutoff angle (or 180 for point source).
M_Real spot_exponent	Spotlight intensity distribution.
M_Vector3 spot_dir	Spotlight direction.
M_Real Kc	Constant light attenuation factor.
M_Real Kl	Linear light attenuation factor.
M_Real Kq	Quadratic light attenuation factor.

M_Real(3), M_Vector(3), SG(3), SG_Intro(3), SG_Node(3), SG_View(3)

The SG_Light node class first appeared in Agar 1.6.0.