$flesh

The flesh shader in action.

New in the Orange Box: inside-your-body rendering effects!

While it was only used during the cutscene in Half-Life 2: Episode Two where Alyx is revived, it is pretty versatile due to its amount of parameters.

It displays a second rendering pass on top of the base material which can be blended by adding point_flesh_effect_target entities. When your model gets close to the sphere of these entities, the flesh will start to appear.

Note:The flesh effects will only work when using VertexLitGeneric as your material's shader. Due to this, it only works on models.

Usage

In addition to specifying the essential shader parameters for a VertexLitGeneric material, you have to ensure that your material defines a proxy as such:

 "Proxies"
 {
     "FleshInterior"
     {
     }
 }

This is required to make the shader work, as it has to interact with the world and needs to also animate and update in real-time.

Bug:This shader does not get illuminated from dynamic lighting of Source Filmmaker or env_projectedtexture. Ensure that the map lighting suffices and the player can not use their flashlight (or the map doesn't use this kind of lighting) when a model with this material is shown.  [todo tested in ?]

Shader Parameters

The following shader parameters allow you to enable and control the flesh effect:

$fleshinteriorenabled <bool>

Enables or disables the flesh effect for the material.

$fleshinteriortexture <texture>

The texture used as a base for rendering the flesh. Its alpha value functions as a mask, whereas a higher alpha value (visible) result in that part of the texture showing flesh when an effect target comes close.

$fleshnormaltexture <texture>

Normal map for the flesh effect.

$fleshbordertexture1d <texture>

A texture similar to those used by $lightwarptexture.

Todo: Where on the texture is the "inside" or "outside" of the border effect?

Note:Even when using a fully white border texture and tint, a black tint can still be seen on the border. This is a limitation of the shader and can not be changed.

$fleshsubsurfacetexture <texture>

A texture which is multiplied with the $fleshinteriortexture texture. Use a fully white texture (e.g. vgui/white) to skip this rendering pass.

$fleshsubsurfacetint "[<red float> <green float> <blue float>]"

Allows tinting the $fleshsubsurfacetexture. Default is "[1 1 1]".

$fleshinteriornoisetexture <texture>

Used on the border of the flesh effect, adding a distortion effect on the transition between exterior and interior. Scrolls based on the value of $fleshscrollspeed.

$fleshscrollspeed <float>

Determines how fast the $fleshinteriornoisetexture should scroll.

$fleshbordernoisescale <float>

Changes the scale of the $fleshinteriornoisetexture.

$fleshborderwidth <float>

Determines the width of the border transition between interior and exterior. May change from which camera angles the effect is visible, as well. Must be greater than 0.

$fleshbordersoftness <normal>

Changes how soft the transition between interior and exterior is. Values must be bigger than 0 but no higher than 0.5.

$fleshbordertint "[<red float> <green float> <blue float>]"

Allows tinting the effect border. Default is "[1 1 1]".

$fleshcubetexture <texture>

The cubemap texture to use for reflections on the flesh interior. Accepts values similar to $envmap (including env_cubemap).

$fleshglossbrightness <float>

Changes the strength or brightness of the cubemap reflection (if $fleshcubetexture is specified).

Debugging

Some shader parameters were included to allow for easier debugging, but don't have much use otherwise:

$fleshglobalopacity <normal>

Opacity of the entire flesh effect. Essentially a $alpha for the entire effect.

Note:Since this effect is rendered as a second pass on top of the existing material, you can *not* see through the material when setting this to values less than one. You will instead be seeing the original material behind the flesh effect.

$fleshdebugforcefleshon <bool>

If set to 1, shows the flesh rendering pass on the entire model, regardless of the mask specified on the $fleshinteriortexture or the effect targets.

$flesheffectcenterradius<1/2/3/4> "[<x float> <y float> <z float> <radius float>]"

If any of these shader parameters are specified, a flesh effect target is created at the specified location (

Todo: using local or world coordinates?

) using the specified radius. This functions the same as adding a point_flesh_effect_target entity.

Todo: Can you have more than four point_flesh_effect_target entities? If not, will these parameters interfere with those entities / override their settings?