Fader

Based on game build 714014 | Last updated: 2026-03-03

Overview

Fader is a lightweight component that performs linear value interpolation over time. It is typically attached to entities that need smooth transitions of numeric properties (e.g., opacity, scale, sound volume) via custom setter functions. The component tracks one or more concurrent fade operations, updates them each frame, and cleans up completed fades automatically.

It does not manage rendering or physics directly—instead, it delegates the actual value assignment to a provided setter function, enabling integration with arbitrary property systems.

Usage example

local inst = CreateEntity()
inst:AddComponent("fader")

-- Fade an entity's alpha from 1.0 to 0.0 over 2 seconds
local setter = function(val, target)
    target.Transform:SetHide(true)
    target.AnimState:SetMultAlpha(val)
end

inst.components.fader:Fade(1.0, 0.0, 2.0, setter)

Dependencies & tags

Components used: None
Tags: None identified.

Properties

Property	Type	Default Value	Description
values	table	{}	Array of active fade operations; each entry contains interpolation state.
numvals	number	0	Count of active fade operations.

Main functions

Fade(startval, endval, time, setter, atend, id)

• Description: Starts a new fade operation, interpolating from startval to endval over time seconds. Updates the value via setter(val, inst) each frame, and optionally calls atend(inst, val) when complete.
• Parameters:
  • startval (number) — initial value of the fade.
  • endval (number) — target value at the end of the fade.
  • time (number) — duration in seconds.
  • setter (function) — callback taking (val, inst) to apply the interpolated value.
  • atend (function, optional) — callback taking (inst, final_val) fired when fade completes.
  • id (number or string, optional) — user-defined identifier; defaults to 1-based index.
• Returns: number — the assigned fade ID (either provided or auto-incremented).
• Error states: None.

StopAll()

• Description: Immediately finishes all active fades by setting all values to their endval, triggers each atend callback (if any), clears the fade queue, and stops component updates.
• Parameters: None.
• Returns: Nothing.

OnUpdate(dt)

• Description: Internal frame update handler invoked by the engine. Advances all active fades by dt seconds, updates via setter, and removes completed fades.
• Parameters: dt (number) — time elapsed since last frame.
• Returns: Nothing.

Events & listeners

• Listens to: None
• Pushes: None