Template:Shaderparam It allows for a second UV channel to be defined for a model, allowing a decal texture to be placed on top of the base material. To use the parameter, the MDL must have been compiled from an FBX file and have a second UV channel defined.
Bug:Using VBSP's -StaticPropCombine parameter appears to break this effect on autocombined models in some cases. [todo tested in ?]
Here, each label on the crates is laid out on a separate UV channel to that of the main texture – this allows easy and efficient reuse of the same labels/decals on many different props without losing texture resolution.
Parameters and Effects
$decaltexture
$decalblendmode