Alphatexture

%alphatexture is an internal material shader parameter available in Garry's Mod. Used on static props when the prop is flagged for texture shadows and compiling VRAD with -textureshadows. The alpha channel of the specified VTF will be used instead of $basetexture, even if $alphatest and $translucent are absent.

This parameter can be useful in certain niche instances:

• When $detailblendmode 4 is used, as the shadows would then make more sense to be cast from $detail
• When $additive is used, as no alpha channel will be present and neither $translucent nor $alphatest are used
• When a shader such as Refract is used, as no alpha channel will be present and neither $translucent nor $alphatest are used, and $basetexture won't be used as the diffuse
• If a shader such as Wireframe is used, as $basetexture will not be present
• When $alpha is used

Note:As this parameter is only used by VRAD, the VTF mentioned does not need to be shipped with the map if it is unused elsewhere.

Todo: Implementing in custom VRAD; see GitHub commit which was used in gmod feature request.

Syntax

"VertexLitGeneric"
{
    $basetexture "models/props_custom/myprop_base"
    %alphatexture "models/props_custom/myprop_alpha"
}