WorldVertexTransition

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Application without and with $blendmodulatetexture.

WorldVertexTransition is a pixel shader available in all Source games. It is a shader functionally similar to LightmappedGeneric primarily used to perform a per-vertex linear blend between two textures on a displacement surface. Many of the parameter definitions for the secondary material are the same as the first material except with a "2" at the end. ex: $basetexture2

You can choose which texture you would like to appear on a vertex using Hammer's alpha painting tool. The blend is normally a linear gradient, but you can control the blend on a per-pixel basis by specifying $blendmodulatetexture in the material.

Important:In Black Mesa this shader was missed in the deferred renderer update. Instead, use LightmappedGeneric, which, in Black Mesa, has all the features of WorldVertexTransition.

Caveats

Note:You can also use $vertexalpha to create a material that fades out. This uses the first $basetexture then fades out with the blend. Unfortunately, it is treated the same as a material with $translucent and can have sorting issues with other transparency objects.

Note:This shader now only works on displacements. If used on a regular brush, VBSP will generate and pack a LightmappedGeneric version of the material automatically, discarding the secondary texture.

Note:The shader LightmappedGeneric does texture blending as well and supports many of the same features as this shader.

Confirm:Does WorldVertexTransition support any features that LightmappedGeneric does not?

Bug:$blendmodulatetexture does not display in hammer despite the shader LightmappedGeneric displaying it correctly. Instead it displays a linear blend. This has been fixed in   [todo tested in?]

Todo: This shader was significantly upgraded in with new parameters, a new layer blending mode, drop shadows, and support for layer-specific detail textures and specular masks. Document these.

Example

WorldVertexTransition
{
	$basetexture nature/dirtfloor006a
	$surfaceprop dirt

	$basetexture2 nature/rockfloor005a
	$surfaceprop2 rock

	%tooltexture nature/blendrockgrass004a_tooltexture
}

• Some visual effects can be selectively applied to one sub-material or the other. See the relevant articles for more details.
• The Hammer material browser won't be able to display a preview of the material unless it's given a %tooltexture.

Supported Parameters

$basetexture <texture>

The first texture in the blend.

$basetexture2 <texture>

The second texture to blend to.

$bumpmap <texture>

bumpmap for the first texture.

$bumpmap2 <texture>

bumpmap for the second texture.

$blendmodulatetexture <texture> (in all games since )

Modulate the blending between materials using a special texture.

$detail <texture>

Detail texturing. Applies the same detail texture to both materials. In , each layer can use their own detail texture.

$envmap <texture>

Specular reflections. In , each layer can have their own specular mask.

Todo: Might disable $blendmodulatetexture if both are used.

$lightwarptexture <texture> (in all games since )

Per-texel color modification via a warp texture. Applies the lightwarp to both materials.

$seamless_scale <float> (in all games since )

Mitigation for displacement texture stretching.

$selfillum <boolean>

Self-illumination. Applies the self-illumination to both materials.

Todo: Might disable $blendmodulatetexture if both are used.

$ssbump <boolean> (in all games since )

Self-shadowing bumpmapping. If two bumpmaps are used, both must be self-shadowing bumpmaps in order for this to work properly.

$translucent <boolean>

$alpha <float>

Expensive and cheap transparency^[Clarify]. Applies the transparency to both materials.

$vertexalpha <boolean>

Causes the material to blend between the primary texture and full transparency. Automatically marks the material as $translucent. Requires $vertexcolor to be set to 1.

$additive <boolean>

Adds the color of the pixels on the surface with the pixels of objects behind it.

$phong <boolean> (only in )

Diffuse reflections.

$phong_exp <float> (only in )

Confirm:Is this for LW's Blinn–Phong reflections?

$phong_exp2 <float> (only in )

Confirm:Is this for LW's Blinn–Phong reflections?

$layertint1 <color255> (only in )

SRGB tint layer 1.

$layertint2 <color255> (only in })

SRGB tint layer 2.

[[%detailtype|%detailtype]] <string>

Specifies what Detail props to spawn on the material. The string should be the name of a detail type outlined in "detail.vbsp" or your specified .vbsp file.

Note:On some materials, the sprites only show up on $basetexture, but not on $basetexture2. This may also happen when you make your own blend material using rocks and grass. If rock is $basetexture, only the rock will have grass sprites, which looks odd.

See also

• LightmappedGeneric, the standard shader for lightmapped surfaces.
• Lightmapped_4WayBlend, an upgraded displacement blend shader for .
• LightmappedTwoTexture, a brush shader that multiplies a texture on top of another one.
• WorldTwoTextureBlend, a brush shader that applies a texture on top of another one using $detail.
• Displacement, the surface type this shader is used on.