$phong

$phong is a material shader parameter for the VertexLitGeneric shader available in all Source games since Source 2006.

Phong shading provides Alyx's skin, hairband and lip highlights.

It is also available on the LightmappedGeneric and WorldVertexTransition shaders in all games since Counter-Strike: Global Offensive(also in ). It provides  diffuse reflections at low intensity and  specular highlights at apex intensity, masked by a texture which control per-texel its intensity. For a full explanation, see Phong materials.

Syntax

$phong <bool>

Note:All parameters in the following example must be specified in the material, otherwise Phong shading won't show up at all, except in Insurgency.

Todo: Other games that don't require all phong parameters present (likely Portal 2 and up)

VertexLitGeneric
{
	$phong 1

	$bumpmap				[texture]
	$phongexponent			5			// either/or
	$phongexponenttexture	[texture]	// either/or
	$phongboost				1.0
	$phongfresnelranges		"[0 0.5 1]"
}

Parameters

Masking

Warning:There are some caveats regarding $normalmapalphaenvmapmask and $selfillumfresnel when using $phong!

• Using $selfillumfresnel without $normalmapalphaenvmapmask will mask the $envmap using the $basetexture's alpha channel.
• Using $selfillumfresnel with $normalmapalphaenvmapmask will multiply the $envmap by 0.0f. Effectively disabling the effect!
• When not using $selfillumfresnel. The mask used for $envmap will be the $basetexture's alpha channel unless $normalmapalphaenvmapmask is also used.
• If $normalmapalphaenvmapmask is used, the $bumpmap's alpha channel will be used for Phong masking. Using either $basemapalphaphongmask or $basemapluminancephongmask will override it.

$bumpmap <texture>

Phong requires mask. The alpha channel of a bump map acts as a Phong mask by default.

$basemapalphaphongmask <boolean> (in all games since )

 Shader(s): VertexLitGeneric

Use $basetexture's alpha channel as the Phong mask instead of $bumpmap's alpha channel.

Warning:Using this with $normalmapalphaenvmapmask will override the mask used for $envmap to be the contents of the $basetexture's alpha channel!

Warning: Garry's Mod Using this with $normalmapalphaenvmapmask and $envmap renders in $envmap and $phong be masked by both $basemapalphaphongmask alpha channel and $normalmapalphaenvmapmask alpha channel.

$basemapluminancephongmask <boolean> (in all games since )

 Shader(s): VertexLitGeneric

Mask phong intensity based on the brightness of the $basetexture.

Bug:Basetexture Luminance will replace the mask used for $envmap, if $normalmapalphaenvmapmask is used.  [todo tested in ?]

Bug:Doesn't work in Garry's Mod.  [todo tested in ?]

$phongexponent and $phongexponent2 <integer>

A global exponent value. Overrides an exponent mask if present.

$phongexponent2 is for WorldVertexTransition's second material in CS:GO engine branch.

$phongexponenttexture <texture>

 Shader(s): VertexLitGeneric

A per-texel exponent map. In an exponent map:

• Red channel: Exponent mask (size of highlight, 0-255, where a value of 0 is a large highlight, 255 small.)
• Green channel: Albedo tint mask (only if $phongalbedotint 1, 0-255, where a value of 0 is no tint, 255 full tint.)
• Blue channel: Nothing.
• Alpha channel: $rimlight mask (only if $rimmask 1.)

Note:LightmappedGeneric and WorldVertexTransition do not have support for $phongexponenttexture. You must use $phongexponent instead.

$phongexponentfactor <float> (only in )

 Shader(s): VertexLitGeneric

Multiply the exponent from the $phongexponenttexture by this amount.

Tip: The default value of this parameter is "0.0". However, a more reasonable default value would be "149.0"

$invertphongmask <boolean> (in all games since )

 Shader(s): VertexLitGeneric

Invert the value of the phong mask.

Bug:In s and s Shadercode, using this parameter will invert the mask used for $envmap, not the one used for $phong!   [todo tested in ?]

Confirm: Is this the case for all branches?

$forcephong <boolean> (in all games since )

 Shader(s): VertexLitGeneric

Force phong shading on phong-using materials even at low GPU levels when mat_phong is disabled.

$diffuseexp <float> (only in )

 Shader(s): VertexLitGeneric, Infected

Diffuse exponent used for dynamic lights only.

Note:have this with $halflambert greatly decrease it effect.

$shinyblood <integer> (only in )

 Shader(s): VertexLitGeneric, Infected

Derive phong mask from areas that are more red than others. Only when variation is disabled.

$shinybloodexponent <integer> (only in )

 Shader(s): VertexLitGeneric, Infected

Exponent for the above.

Brightness

$phongboost <float>

 Shader(s): VertexLitGeneric, LightmappedGeneric((only in ))

Phong brightness factor. Larger values create a more intense highlight, useful for surfaces like metal and glass.

Tip:A phong boost of zero is visually identical to no phong, and can be used to work around certain shader parameter combinations that require phong (ex $lightwarptexture).

$phongfresnelranges <matrix>

 Shader(s): VertexLitGeneric, LightmappedGeneric((only in ))

See Phong Fresnel ranges. Default is "[0 0.5 1]".

Note:$envmap is also affected by these fresnel ranges if both it and Phong are enabled in a material.

Note: drives the x component of a phongwarptexture if specified.

$phongdisablehalflambert <boolean> (in all games since ) (also in ,)

 Shader(s): VertexLitGeneric

Disables forced half-lambertian shading on Phong materials.

Note:This parameter is effectively forced on in CS:GO engine branch due to $halflambert being disabled.

Tip:In games without this command, the effect can be simulated by using the $lightwarptexture found here.

Colors

$phongalbedotint <boolean> (in all games since )

 Shader(s): VertexLitGeneric

Tints the phong reflection by the color of the $basetexture. The amount of tint is defined by the green channel of $phongexponenttexture. A $phongexponenttexture must be specified in order for $phongalbedotint to work.

Warning:$phongalbedotint cannot be used with $phongtint. The latter will disable the effect.

Note:$phongalbedotint works by multiplying the $basetexture over the reflection, without darkening the albedo. The reflection will get dimmer as a result, so account for this in the phong mask or with $phongboost.

Note:$phongalbedotint will tint highlights by the original color of the $basetexture even when the material is tinted by $color2 or rendercolor.

An example model showing how AlbedoTint appears on a model.

$phongalbedoboost <float> (in all games since ) (also in )

 Shader(s): VertexLitGeneric

Phong albedo overbrightening factor. Ranges 0-255.

Note: This will multiply the tint that is being applied to phong from $phongalbedotint.

Bug: This does not work when using $detail.   [todo tested in ?]

The Hunter without and with its $phongwarptexture, showing how it affects the Phong reflection.

$phongtint <RGB matrix> (in all games since )

 Shader(s): VertexLitGeneric

Color tint of the phong reflection.

Warning:This will override $phongalbedotint if both are used.

Note: Also tints $rimlight

Breakdown of the $phongwarptexture: computed coordinates, texture and result

$phongwarptexture <texture> (in all games since )

 Shader(s): VertexLitGeneric

Used to create an iridescence effect, as seen on Episode Two's Hunters.

The highlight is multiplied with a texture. The coordinates of the sampled pixel are as follows:

x: 1 - (distance to the center of the highlight)

y: 1 - (fresnel component as computed by Phong Fresnel ranges)

Note:Disables the initial phongfresnelranges masking

Bug:Does not work in Left 4 Dead 2.  [todo tested in ?]

Brush phong in Counter-Strike: Global Offensive using tile/hr_t/inferno/tile_a. Note the complete absence of the reflection in the shaded area.

Brush Shader Parameters

(only in )(also in )

$phongmaskcontrastbrightness and $phongmaskcontrastbrightness2 <vector2>

 Shader(s): LightmappedGeneric, WorldVertexTransition

The first value controls the contrast level between light and dark areas in the mask, and the second value controls the overall brightness.

$phongmaskcontrastbrightness2 is for WorldVertexTransition's second material.

Todo: Find out the range of both values.

$phongamount and $phongamount2 <vector4>

 Shader(s): LightmappedGeneric, WorldVertexTransition

The first 3 values control the color tint, and the fourth value controls the brightness. The fourth value can go beyond 1, but affects the brightness of the whole texture, not just the highlight.

$phongamount2 is for WorldVertexTransition's second material.

$phongbasetint and $phongbasetint2 <float>

 Shader(s): LightmappedGeneric, WorldVertexTransition

Allows the $basetexture and/or $basetexture2 to tint the color of the Phong highlight.

Console Commands

Cvar/Command	Parameters or default value	Descriptor	Effect
mat_phong	1	bool	Disable or enable phong shading. Bug:Doesn't work in Counter-Strike: Global Offensive branch.  (tested in: )

Notes

Note:Phong shading for LightmappedGeneric and WorldVertexTransition is only available in . It requires the material to be lit by the sunlight from a env_cascade_light entity to work properly and uses the dynamic shadows generated by it as a mask on top of the traditional phong masking. ((in all games since ) env_projectedtexture also affects brushes with phong enabled)

Bug: Garry's Mod reads lighting direction for brush phong from env_sun instead; maps with multiple suns may not get accurate phong reflections on brushes.

Note:Phong shading for LightmappedGeneric is also available in Mapbase, but it is implemented differently.

Important:In all Source Engine games since Source 2007 (until ) enabling this shader will also enable $halflambert automatically (including gbuffer's halflambert in Black Mesa), unless $phongdisablehalflambert(in all games since ) is used. This effect isn't physically accurate, so it should be disabled if possible in most cases.

Bug:Phong reflection vectors are broken on static props with vertex lighting.  (tested in: ,)

Tip:Use new specular shader in Black Mesa as an alternative of phong on brushes.

See also

• Phong materials
• $envmap (environment map)
• $lightwarptexture
• $rimlight

External links

•  A comprehensive YouTube video on how phong materials work in Source
• $Phong on brushes*: The Hacky Way - A TF2maps.net guide on how to fake $Phong on brushes for games prior to CS:GO. Can also be used to fake phong on static props which are lit per-vertex, without falling back to lower-quality point lighting on the main prop
• SubstancePainter Source Engine Complex Phong Shader