View source for Half Lambert

[[File:Alyx_lambert_half_lambert.jpg|right|200px|thumb|Alyx model showing Lambertian lighting (left) and Half Lambert lighting (right)]]
'''Half Lambert lighting''' is a technique designed to prevent the rear of an object losing its shape and looking too flat.

Half Lambert is a completely non-physical technique{{clarify}} and gives a purely percieved visual enhancement and is an example of a forgiving lighting model.

== Games ==
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# {{hl|4}}

==Implementation==
[[File:Lambert vs halflambert.png|right|200px|thumb|The Lambertian dot product lobe (red) vs. the Half Lambertian dot product lobe (blue)]]
To soften the diffuse contribution from local lights, the dot product from the [[wikipedia:Lambert's cosine law|Lambertian model]] is scaled by ½, add ½ and squared. The result is that this dot product, which normally lies in the range of -1 to +1, is instead in the range of 0 to 1 and has a more pleasing falloff.

In the original {{hl1|4.1}}, where this diffuse Half Lambert term was the only term in most of the model lighting, it kept the characters in particular from being lit exclusively by a constant ambient term on the back side with respect to a given light source.

In {{src|4.1}}, Half Lambert lighting can most often be seen being used on the characters face materials. It is enabled by the use of {{mono|[[$halflambert]]}} within a material's [[VMT]] file.

==See also==
* [[$halflambert]] - [[VMT]] shader parameter to enable Half-Lambert lighting.

[[Category:GoldSrc]]
[[Category:Source]]

[[Category:Material System]]