Lighting

is an option for Graphics3D and related functions that specifies what simulated lighting to use in coloring 3D surfaces.

Details

The following settings can be given:
Automatic default lighting schemes

None no lighting

{s₁,s₂,…} light sources s₁, s₂, …
Each light source can be of the following forms:

	{"Ambient",col}	uniform ambient light of color col
	{"Directional",col,pt}	directional light from pt to the center of the bounding box
	{"Directional",col,{pt₁,pt₂}}	directional light along the vector from pt₁ to pt₂
	{"Point",col,pt}	spherical point light source at position pt
	{"Point",col,pt,att}	point light with geometric attenuation att
	{"Spot",col,pt,α}	spotlight at pt aimed at the center with half-angle α
	{"Spot",col,{pt,tar},α}	spotlight at pt aimed at tar with half-angle α
	{"Spot",col,{pt,tar},{α,s},att}	spotlight with spot exponent s and attenuation att

	{x,y,z}	explicit coordinates that move with the graphic
	Scaled[{x,y,z}]	scaled coordinates that move with the graphic
	ImageScaled[{x,y,z}]	coordinates fixed relative to the final displayed image

In ImageScaled[{x,y,z}], the and run from 0 to 1 across the width and height of the bounding box of the final displayed image. The coordinate runs orthogonal to the plane of the display, and is 0 at the back of the 3D region, and 1 at the front.
Coordinates specified in Scaled and ImageScaled will often not be between 0 and 1.
Lighting->Automatic uses ambient light together with four light sources fixed relative to the final displayed image. With the typical default setting ColorFunction->Automatic, colored light sources are used; if an explicit setting for ColorFunction is given, the light sources are taken to be white. »
Lighting->"Standard" always uses colored light sources in the default positions. »
Lighting->"Neutral" always uses white light sources in the default positions. »
Lighting can be specified globally for a 3D graphic by giving a Lighting option for Plot3D, Graphics3D, etc.
Lighting can be specified separately for particular objects in Graphics3D by giving a style option Style[obj,Lighting->spec]. »
In a list of graphics primitives and directives, the alternative form {…,g,Lighting->spec,g,…} defines lighting for objects that follow the lighting specification in the list. »
The final colors of 3D surfaces are determined by linearly adding RGB colors from three sources:

	diffuse reflection defined by RGBColor etc. directives
	specular reflection defined by Specularity directives
	glow defined by Glow directives

The setting for Lighting affects only colors associated with diffuse and specular reflection.
Diffuse reflection is taken to follow Lambert's law, with light effectively scattered equally in all directions from a surface.
Specular reflection effectively takes light to be scattered only close to the mirror‐reflection direction, as specified in the notes for Specularity.
Colors of light sources can be defined by RGBColor, Hue, or any other color specification.
Light sources with color specifications of the form {dcol,Specularity[scol]} are effectively taken to have colors dcol for purposes of diffuse reflection, and scol for purposes of specular reflection. »
Directional light sources specified by {"Directional",col,{pt₁,pt₂}} are taken to yield parallel simulated light rays, so only the direction vector defined by {pt₁,pt₂} is relevant, not its magnitude. »
Point light sources specified by {"Point",col,pt} effectively yield light that emanates from the point pt but does not attenuate with distance. »
{"Point",col,pt,{a,b,c}} yields light that attenuates like with distance . »
{"Spot",col,{pt,tar},α} yields the same light distribution as a point light source, except that it is restricted to a cone with direction from pt to tar, and with half-angle in radians. »
{"Spot",col,{pt,tar},{α,s}} gives fall-off away from the center of the cone. »
{"Spot",col,{pt,tar},{α,s},{a,b,c}} gives attenuation with distance . »