The vr_standard shader used in SteamVR Home is a Physically Based Rendering (PBR) shader similar to shaders used in other modern game engines. It does however not conform to the spec/gloss or metal/rough workflows directly, so texture maps designed for other games or exported from texturing tools used may need to be modified before they can be used.

As always, any feedback and suggestions are appreciated.

More general information is available in the official Dev Wiki:
Materials, Details and Props, includes an overview about material creation.
Creating a Physics Prop, includes more information about shader parameters.

My old guide on Destinations PBR materials still applies here (some of the information may be outdated).
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=783210669


To properly test materials, make sure to use a testing map with map with properly set up lighting. Bake indirect lighting using light probe volumes and cubemaps.

Indirect specular reflections do not show up in the model and material editors when using world cubemaps. To quickly inspect them, the setting can be switched over to artist cubemaps for a default cloudy sky. Don't forget to switch back afterwards.

Use linear color profiles when working with non-color data such as gloss and reflectance maps.

Here is a list of the most commonly used maps in the shader.

Color
Equivalent to the Substance Painter Base Color map. This is the surface albedo of both the diffuse and specular lighting. On metallic materials the color of the metal is defined here.












Normal Map
An OpenGL style tangent space normal map with a positive green channel (+Y).














Reflectance
Describes the reflectivity of the material. This determines how much of the incoming light is reflected specularily and diffusely respectively. This is entirely determined by the type of the material, and there are lists available online of what values different materials should have. A good rule of thumb is between 0.05 - 0.1 for non-metallic materials and around 1 for pure metals. Values between that are uncommon apart for thin layers of corrosion or dirt on metals.






Gloss
Controls the smoothness of the surface. Wear and dirt are primarily applied here, so editing this can apply a lot of personality to the material. This should be the texture primarily edited when you want to adjust the reflections. This seems to come out glossier than in Substance Painter, so toning down the levels can help.









Metalness
Primarily affects the specular color, areas where this is enabled tint reflections from the Color map while unaffected areas have untinted reflections. Metallic areas should be white and non-metals should be black.












Ambient occlusion
Map describing how much the surface is occluded from ambient lighting. Mostly useful for models with unique geometry.

For metallic models or composite models with both metallic and non-metallic parts, the metal/rough workflow works the best. It is the standard shader for Substance Painter and it supports conversion to spec/gloss maps.

Create your material using the default maps of the pbr-metal-rough shader, as well as ambient occlusion if needed.




To export, create a new export configuration preset using the settings below. Note the file name postfixes used by the Workshop tools to filter textures by type.



Export the maps using a lossless format such as PNG or TGA.


The converted specularity and gloss maps do not match the ranges used in SteamVR Home, so to get proper results they need to get adjusted in an image editor.

The Reflectance map comes out compressed to the mid-ranges and needs to be stretched out to increase the contrast. Make sure non-metallic areas have a brightness around 0.05 to 0.1 and fully metallic areas around 1.



Original | Adjusted


The gloss map needs to be darkened from the Substance Painter output. This is highly subjective, so test and iterate on the result.



Original | Adjusted




Move the maps to a subdirectory of the materials directory of your add-on, and open/create a material. In the material editor enable the following options as needed:

Specular - Enables real time reflections and the Reflectance map.

In-Game Cube Map - Enables indirect Cubemap reflections.

Specular Cube Map Projection - Projects box cubemaps to the correct position in the world, very useful on items that are expected to move in the environment.

High Quality Gloss - Having this unchecked bakes the gloss and normal maps in the same texture.

Metalness Texture - If you made a metalness map that is more than a flat color.

Ambient Occlusion Texture - If you made an AO map.


If the maps have the same name/location as the material, they should get filled in automatically based on the postfix when the corresponding options are enabled.

If the model does not have any metallic or highly reflective parts, the specular/gloss workflow can be used instead. Substance Painter does not support converting spec/gloss materials to the necessary maps, but with low specular levels the diffuse and specular color maps can be used as the base texture and reflectance maps.

Create your material using the default maps of the pbr-spec-gloss shader, as well as ambient occlusion if needed.




To export, create a new export configuration preset using the settings below. Note the file name postfixes used by the Workshop tools to filter textures by type.



Export the maps using a lossless format such as PNG or TGA.


The specularity and gloss maps do not match the ranges used in SteamVR Home, so to get proper results they need to get adjusted in an image editor.

The Reflectance map comes out compressed to the mid-ranges and needs to be stretched out to increase the contrast. Make sure non-metallic areas have a brightness around 0.05 to 0.1 and fully metallic areas around 1.

Note that a reflectance map is not always required, a single value can be set in the Material editor.




Original | Adjusted



The gloss map needs to be darkened from the Substance Painter output. This is highly subjective, so test and iterate on the result.




Original | Adjusted



Importing the maps to the Workshop tools works the same as for the metal/rough material.