Definitions

Definitions describe the types of objects in Railroader — cars, locomotives, props, loads, and more. Each definition specifies the properties and components that make up an object type.

Definitions.json

Definitions are declared in a Definitions.json file inside an asset pack. The file contains an array of definition entries:

[
  {
    "identifier": "my-pack/my-boxcar",
    "metadata": {
      "name": "My Boxcar",
      "description": "A custom boxcar.",
      "tags": ["freight"],
      "credits": "Author Name"
    },
    "definition": {
      "kind": "Car",
      "modelIdentifier": "./my-boxcar-model",
      "carType": "XM",
      ...
    }
  }
]

Each entry has:

Field	Type	Description
identifier	string	Unique ID in domain/name format
metadata	object	Display information (see below)
definition	object	The definition object, distinguished by kind

Metadata

Field	Type	Description
name	string	Display name
description	string	Short description
tags	string[]	Categorization tags
credits	string	Attribution

Base Fields

All definitions share these fields:

Field	Type	Default	Description
kind	string	—	Discriminator that selects the definition type
components	Component[]	[]	Components attached to this definition

Every other field comes from the kind — see each kind’s own page for its full field list.

Definition Types

Kind	Description
Car	Freight and non-powered rolling stock
SteamLocomotive	Steam-powered locomotive
ArticulatedSteamLocomotive	Articulated (Mallet) steam locomotive
DieselLocomotive	Diesel-electric locomotive
Prop	Scenery object placed in the world (buildings, masks)
Truck	Wheel truck / bogie
Load	Freight or cargo type
StaticLoadModel	Visual model for a load (static placement)
LinearLoadModel	Visual model for a load (linear repeating)
Material	Material override
Texture	Texture asset reference (e.g. builder photos)
CarStyle	Car paint scheme
ReportingMark	Declares that a railroad exists
Whistle	Steam whistle audio/model
Horn	Diesel horn audio/model
Bell	Locomotive bell audio

Inheritance

Some definitions extend others, inheriting all of their fields:

ObjectDefinition
├── Car
│   ├── SteamLocomotive
│   │   └── ArticulatedSteamLocomotive
│   └── DieselLocomotive
├── Prop
├── Truck
├── Load
├── StaticLoadModel
├── LinearLoadModel
├── Material
├── Texture
├── CarStyle
├── ReportingMark
├── Whistle
├── Horn
└── Bell

For field types like AssetReference, AnimationReference, and TransformReference that appear across multiple definitions, see Common Types.