Components

Components add features to definitions — visual details, interactive controls, sounds, lights, and more. They are listed in a definition’s components, keyed by component id.

Base Fields

All components share these fields:

Field	Type	Default	Description
`kind`	string	—	Discriminator that selects the component type
`name`	string	—	Component name (used for identification)
`transform`	Transform	identity	Position, rotation, and scale
`parent`	TransformReference	`null`	Parent transform in the model hierarchy
`enabled`	bool	`true`	Whether the component is active

Transform

Field	Type	Default	Description
`position`	float[3]	`[0, 0, 0]`	Position offset [x, y, z]
`rotation`	float[4]	`[0, 0, 0, 1]`	Rotation quaternion [x, y, z, w]
`scale`	float[3]	`[1, 1, 1]`	Scale multiplier [x, y, z]

Component Ids

A component’s id is its name within the definition it belongs to, and it is what the Definition Editor labels the component with in its list. Set it in the Id field at the top of the component inspector; the editor starts you with one derived from the component’s name and rejects a rename that collides with another component in the same definition.

Ids are how a style rule names one specific component ("Decal#left-number-board") and how a Relay script looks one up, so an id can only include the same characters as a style class — see Names Within a Definition.

Example

{
  "kind": "Car",
  "components": [
    {
      "kind": "Ladder",
      "height": 4.0,
      "name": "Ladder",
      "transform": {
        "position": [1.3, 0.0, 6.5],
        "rotation": [0.0, 0.0, 0.0, 1.0],
        "scale": [1.0, 1.0, 1.0]
      },
      "parent": null,
      "enabled": true
    }
  ]
}

Availability

Each component is available on certain definition types:

Availability	Definitions
Car	Car definitions only (Car, SteamLocomotive, DieselLocomotive, etc.)
Prop	Prop definitions only
Truck	Truck definitions only (wheel trucks/bogies attached to a car)
Any	Car, prop, and truck definitions

Component Reference

Kind	Availability	Description
`AggregateLoadModel`	Car	Animated aggregate load visual (coal, gravel)
`AimConstraint`	Car	Rotates a transform to aim at another (experimental)
`Bell`	Car	Locomotive bell
`Chuff`	Car	Steam exhaust chuff effect
`ClassLight`	Car	Classification light
`Compressor`	Car	Air compressor
`CylinderCock`	Car	Steam cylinder cock effect
`Decal`	Car	Text decal (road numbers, data, etc.)
`DetailModel`	Car, Prop	Additional detail model
`DieselExhaust`	Car	Diesel exhaust smoke
`Dynamo`	Car	Electrical generator
`FireboxEffect`	Car	Firebox glow effect
`Gauge`	Car	Cab gauge instrument
`Headlight`	Car	Headlight
`Horn`	Car	Diesel horn
`Ladder`	Any	Climbable ladder
`LightFixture`	Any	Switchable light fixture
`LoadAnimation`	Car	Animation triggered by load state
`LoadModel`	Car	Load-dependent detail model
`LoadModelVolume`	Car	Bounding volume for load models
`LoadTarget`	Car	Interaction target for loading/unloading
`RectangleMapMask`	Prop	Rectangular terrain mask
`CircleMapMask`	Prop	Circular terrain mask
`MarkerLight`	Car	Marker / tail light
`PrefabControl`	Car	Built-in prefab control (brake stand, etc.)
`PropertyAnimation`	Car	Animation posed by a car property (reverser, throttle)
`RadialControl`	Car	Rotary cab control
`RendererGroup`	Car, Truck, Prop	Material / style assignment for renderers
`Script`	Any	Relay script attachment
`Seat`	Any	Occupiable seat
`ToggleAnimation`	Any	Toggle-activated animation
`ToggleControl`	Car	Toggle cab control
`Whistle`	Car	Steam whistle