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Place, switch and make lamps

A lamp is an actor with a BP_LightComponent on it. The component owns the six settings of the lamp. It keeps them in sync for every player and drives every Light the actor carries. You can place the shipped lamps, switch any of them from gameplay, or build your own.

  • The lamps: Content/MPFriendslop/Blueprints/Environments/Lights/Childs/
  • The base class: Content/MPFriendslop/Blueprints/Environments/Lights/BP_LightBase
  • The component: Content/MPFriendslop/Blueprints/ActorComponents/BP_LightComponent
  • The interface: Content/MPFriendslop/Blueprints/Interfaces/BPI_Light

The lamps that ship

Blueprint Mesh Light
BP_CeilingLight_01 SM_CeilingLight_01, a 60 x 60 cm panel One Rect Light
BP_CeilingLight_02 SM_CeilingLight_02, a 120 cm bar One Rect Light
BP_CeilingLight_03 SM_CeilingLight_03, a 100 cm bar One Point Light
BP_FloorNeon_01 SM_FloorNeon_01 One Point Light
BP_FloorNeon_02 SM_FloorNeon_02 One Rect Light
BP_FloorNeon_03 SM_FloorNeon_03 Two Point Lights, Light and UpperLight

The ceiling lamps have their pivot at the fixing point, so they go straight against the ceiling, at Z 300 on the kit. The floor neons have their pivot at the bottom centre and stand on the floor. Every Light is Movable and casts shadows.

Place a lamp

  1. Drag one of the six Blueprints into the level.
  2. Select it and click BP_LightComponent in the Components panel.
  3. Set the fields of Settings|Lighting.
  4. Press Play to judge the result.
Field What it does Default
Is Light Active Off hides every Light of the lamp on
Strength Brightness. Each Light gets Strength x 200 lumens 5, so 1000 lumens
Is Blinking The lamp flickers on and off while it is active off
Blinking Interval Length of one on or off phase, in seconds 1
Blink Randomness 0 gives a steady rhythm. 1 gives the most irregular phases, so lamps drift out of step 0.2
Light Color Colour of every Light of the lamp white

A room of flickering lamps looks best with a short interval and Blink Randomness at 1, so the lamps do not flicker in step. The rooms in Maps/Modules/ use 0.3 seconds.

Warning

The lamp applies its settings when the game starts, not in the editor. The viewport shows the Intensity of the Light component itself, so a level can look black in the editor and be lit in game. If you want the editor to match, also set Intensity on the Light component of that lamp to Strength x 200.

When the whole level is too dark or too bright, do not touch the lamps one by one. Change the locked exposure first, then the fog, as described in How levels are built.

Switch a lamp from gameplay

Every lamp implements BPI_Light. Its six messages match the six fields: SetLightActive, SetStrength, SetBlinking, SetBlinkingInterval, SetBlinkRandomness and SetLightColor. Each takes one input, Value. A power cut, an alarm or a quest step can drive any lamp through the interface without knowing its class.

The same six functions exist on BP_LightComponent itself, if you already hold a reference to the component.

Dispatcher Fires on When
OnLightStateChanged every player A setting changes, or the lamp flickers on or off

Bind OnLightStateChanged for a buzz sound, a spark effect or a HUD icon. It has no parameters: read the fields of the component to know the new state.

The lamps do not implement BPI_Activatable when they ship, so a button or a lever cannot switch them as they are. The recipe to add it is in Make your own door, switch or lever.

Make your own lamp

  1. Right click BP_LightBase, then Create Child Blueprint Class.
  2. Add a Static Mesh component with your fixture.
  3. Add one or more Light components: Point, Rect or Spot.
  4. On each Light, set Intensity Units to Lumens and Mobility to Movable.

You do not wire anything. BP_LightComponent finds every Light of its actor on its own, so a lamp with three Lights switches all three. The Lumens unit matters: it is what makes Strength x 200 mean the same brightness on your lamp as on the shipped ones.

For a lens that glows with the lamp, put MI_LightDiffuser on the lens slot of your mesh. The component writes Strength into the LightStrength parameter and Light Color into the EmissiveColor parameter of every material of the actor, so the lens dims, changes colour and goes dark with the Lights. A material of your own glows the same way if it has those two parameters. The scalar name is Scalar Parameter Name on BP_LightComponent, in Settings|Materials.

The component works on any actor, not only on children of BP_LightBase. Add a BP_LightComponent to a vending machine or a computer and it drives the lights of that actor. Only children of BP_LightBase answer BPI_Light, though: on another actor, call the functions of the component, or add the interface yourself.

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