Shaders

Railroader provides several shaders for use in asset packs. These are distributed in the shared asset pack and are available to all mods. The ADK includes a copy of this pack so your materials can use them; see Shared Assets.

We strongly recommend using the provided shaders rather than URP/Lit. The provided shaders are shared across all asset packs, so using them keeps your asset pack smaller by avoiding bundling duplicate shader code. Using a common set of shaders also improves rendering performance, as shared shaders batch more efficiently. Finally, the provided shaders are tuned for Railroader’s visual style, for a consistent appearance across the game.

Shader Overview

Shader	Use Case
Standard Car Shader	Rolling stock (cars, locomotives)
Standard Environment Shader	Scenery and structures
Standard Shader	Simple objects without wear or UV1 features
Aggregate Shader Stochastic	Ground/ballast with stochastic tiling

The Car, Environment, and Standard shaders are each available in Metallic and Specular variants. The metallic workflow is recommended for new content.

Texture Import Settings

Texture	sRGB	Import Type
MainTex / BaseMap	Yes	Default
Normal Map	No	Normal map
MetallicGlossMap	No	Default
Specular Map	Yes	Default
OcclusionMap	No	Default

Textures containing non-color data (normals, metallic, AO, smoothness) must be imported as Linear (sRGB unchecked). Base color / diffuse textures and the Specular Map use sRGB, since both hold color. The Specular Map’s alpha carries smoothness, which is unaffected — Unity never applies the sRGB curve to an alpha channel.

For how to produce these maps out of Substance 3D Painter with the right channels in the right places, see Texturing Workflow.

Car Shaders

The car shaders are the simplest option for rolling stock. At runtime, Railroader replaces these shaders with builtin versions and applies wear automatically based on car condition. You do not need to configure wear properties on car materials.

Standard Car Shader Metallic

Texture	Channel Mapping
MainTex	RGB = Base color
Normal Map	Tangent-space normal
MetallicGlossMap	R = Metallic, G = Ambient occlusion, A = Smoothness

Properties:

Property	Type	Default	Description
Base Color	Color	—	Tint multiplied with MainTex
Smoothness	Float	0.92	Multiplied with MetallicGlossMap alpha

Standard Car Shader Specular

Texture	Channel Mapping
MainTex	RGB = Base color
Normal Map	Tangent-space normal
Specular Map	RGB = Specular color, A = Smoothness
OcclusionMap	G = Ambient occlusion

Properties:

Property	Type	Default	Description
Base Color	Color	—	Tint multiplied with MainTex
Smoothness	Float	0.92	Multiplied with Specular Map alpha

Environment Shaders

The environment shaders add weathering and color variation features for scenery and structures. They are more expensive than the car or standard shaders due to additional texture samples.

Common Environment Features

Both environment shader variants share these features on top of the base PBR inputs:

Wear System: Applies a weathering/aging effect using a triplanar-projected noise texture. The wear intensity is controlled by the Wear property (0 = pristine, 1 = full wear).

Noise Color Pattern: Adds subtle per-object color variation using object-space position to sample a noise texture, mapped through a gradient. This prevents identical objects from looking like copies.

UV1 System: Uses the secondary UV channel (UV1) to blend a tint color and modify ambient occlusion. Controlled by influence properties (default 0 = disabled).

Standard Environment Metallic

Texture	Channel Mapping
MainTex	RGB = Base color
Normal Map	Tangent-space normal
MetallicGlossMap	R = Metallic, G = Ambient occlusion, A = Smoothness
WearNoise	R = Wear pattern (triplanar sampled)
Noise texture	R = Color variation pattern (embedded, not a property)

Properties:

Property	Type	Default	Description
Base Color	Color	—	Tint multiplied with MainTex
Smoothness	Float	0.92	Multiplied with MetallicGlossMap alpha
Tiling	Vector	—	UV tiling for all texture samples
Offset	Vector	—	UV offset for all texture samples
Wear	Float	1	Wear intensity (0 = none, 1 = full)
WearNoise	Texture2D	—	Noise texture for wear pattern
WearColor	Color	—	Color of worn areas
WearNoiseEdge1	Float	0.4	Smoothstep lower edge for wear pattern
WearNoiseEdge2	Float	0.6	Smoothstep upper edge for wear pattern
WearTile	Float	0.04	Triplanar tiling scale for wear noise
WearOcclusionInfluence	Float	1	How much wear darkens ambient occlusion
UV1DiffuseColor	Color	—	Tint color applied via UV1
UV1DiffuseInfluence	Float	0	Strength of UV1 diffuse tint (0 = disabled)
UV1AOInfluence	Float	0	Strength of UV1 ambient occlusion blend (0 = disabled)
UV1Sharpness	Float	0.5	Sharpness of UV1 edge detection

Standard Environment Specular

Texture	Channel Mapping
MainTex	RGB = Base color
Normal Map	Tangent-space normal
Specular Map	RGB = Specular color, A = Smoothness
OcclusionMap	G = Ambient occlusion
WearNoise	R = Wear pattern (triplanar sampled)
Noise texture	R = Color variation pattern (embedded, not a property)

Properties: Same as Environment Metallic above, except uses Specular Map and OcclusionMap instead of MetallicGlossMap.

Standard Shaders

The standard shaders are simple PBR shaders with no wear, noise, or UV1 features. Use these for objects that don’t need weathering effects.

Standard Metallic Shader

Texture	Channel Mapping
MainTex	RGB = Base color
Normal Map	Tangent-space normal
Metallic Gloss Map	R = Metallic, G = Ambient occlusion, A = Smoothness

Properties:

Property	Type	Default	Description
Base Color	Color	—	Tint multiplied with MainTex
Glossiness	Float	0.9	Multiplied with Metallic Gloss Map alpha

Standard Specular Shader

Texture	Channel Mapping
MainTex	RGB = Base color
Normal Map	Tangent-space normal
Specular Map	RGB = Specular color, A = Smoothness
OcclusionMap	G = Ambient occlusion

Properties:

Property	Type	Default	Description
Base Color	Color	—	Tint multiplied with MainTex
Spec Color	Color	—	Tint multiplied with Specular Map RGB
Smoothness	Float	0.92	Multiplied with Specular Map alpha
Tiling	Vector	—	UV tiling for all texture samples
Offset	Vector	—	UV offset for all texture samples

Aggregate Shader Stochastic

A specialized shader for ground surfaces (ballast, gravel, dirt) that uses stochastic texture sampling to break up visible tiling patterns.

Textures:

Texture	Channel Mapping
BaseMap	RGB = Base color
MetallicGlossMap	R = Metallic, A = Smoothness
BumpMap	Normal map
OcclusionMap	R = Ambient occlusion
Height	Height map (stochastic blend weights)

Properties:

Property	Type	Default	Description
Color	Color	—	Base color tint
Tiling	Vector	(1, 3.24)	UV tiling
NormalLevel	Float	1	Normal map strength
StochasticContrast	Float	0.15	Contrast for stochastic blending (0.01–0.99)
StochasticScale	Float	1	Scale of stochastic pattern (0–2)

Texture Channel Packing Summary

Quick reference for how each shader packs data into texture channels.

Normal maps must be in Unity/OpenGL/Y+ format. More information here.

Metallic Workflow Shaders

Channel	MetallicGlossMap
R	Metallic
G	AO
B	—
A	Smoothness

Specular Workflow Shaders

Channel	Specular Map	OcclusionMap
R	Specular color	—
G	Specular color	AO
B	Specular color	—
A	Smoothness	—