$detail

From Valve Developer Community

A detail texture (noise_detail_01), and its effect when applied to a material (left).

$detail specifies a greyscale texture with which Source will add high-resolution detail when the material is viewed up close, by darkening the albedo appropriately. It is very effective for increasing the apparent resolution of a texture, and was used extensively in Episode Two.

Syntax

$detail <texture>

You will probably want to use at least $detailscale (see below) as well.

Additional parameters

$detailscale <float>

Fits the detail texture onto the material the given number of times. Generally around 7 or 8 for a 128px detail texture; default is 4.

$detailblendfactor <normal>

Intensity of the detail's darkening of the albedo. Effectively an $alpha value.

$detailblendmode <bool>

Enable to make the detail texture darken the albedo more.

$detailtint "<RGB matrix>"

Modifies the colour of the detail texture.

$detailframe <int>

The frame to start animated detail texture on. Requires DX9.

$detail_alpha_mask_base_texture <bool?>

To do: Something to do with masking $basetexture with $detail's alpha channel? Requires DX9.

Valve's detail textures

Valve's stock detail textures (available in OB only) are best used with the following pre-configured values:

$detail detail\noise_detail_01 // e.g. for brickwork, concrete...
$detailscale 7.74
$detailblendfactor 0.8
$detailblendmode 0

$detail detail\metal_detail_01
$detailscale 4.283
$detailblendfactor .65
$detailblendmode 0

$detail detail\rock_detail_01
$detailscale 11
$detailblendfactor 1
$detailblendmode 0

$detail detail\plaster_detail_01
$detailscale 6.783
$detailblendfactor .8
$detailblendmode 0

There is also detail\wood_detail_01, but no stock material seems to use it.