$rimlight


... 

$rimlight
is a material shader parameter available in all Source games since
Source 2007

for VertexLitGeneric
. It adds a constant rim light to the model that appears to come indirectly from the environment. The color of the rim light is directly influenced by ambient light and behave closer to $phongfresnelranges Z component.

$phong
to be set to 1.Todo: Explain similarities and differences of Phong Fresnel ranges.
Warning:
Features no visible effect. however, you can increase $phongfresnelranges Z vector to archive a closer effect.
VMT syntax
$rimlight <bool>
VertexLitGeneric { $phong 1 $bumpmap <texture> $phongexponent 5 $phongexponenttexture <texture> $phongboost 1.0 $phongfresnelranges "[0 0.5 1]" $rimlight 1 $rimlightexponent 2 $rimlightboost .2 }
Additional Parameters
Exponent for phong component of rim lighting. The rim exponent defines the "tightness" of the highlight. A higher exponent results in a smaller, tighter highlight while a lower exponent results in a broader flatter one.
Bug:Appears to have no effect in HLMV.

Additive boost for ambient cube component of rim lighting.
By default the rim light is white, This will tint both, phong and rim lighting. See Phong for more.