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LFO & Envelope

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Signal generators for modulation and animation. Both inherit from a common Signals base class that provides trigger/gate management.

Base Class: Signals

Manages attack/release instants from a boolean gate signal.

local Signals = lovjRequire("lib/signals/signals")
local sig = Signals:new()

sig:UpdateTrigger(gateOn)  -- call each frame with true/false
sig:isTriggerActive()      -- true while gate is held

Internally tracks atkInst (attack instant) and rlsInst (release instant) for envelope timing.

LFO

Free-running oscillator with multiple waveforms.

local Lfo = lovjRequire("lib/signals/lfo")
local lfo = Lfo:new(frequency, phase)

Waveforms

All waveforms return values in [-1, 1] and are gated by the trigger state (output is 0 when trigger is inactive).

Method Shape
Sine(t) Smooth sine wave
Square(t) Hard square wave
Triangle(t) Linear triangle
RampUp(t) Ascending sawtooth
RampDown(t) Descending sawtooth
Pulse(t, pw) Pulse with adjustable width (0-1)
RandomSH(t) Random sample-and-hold (new value each half-cycle) 
lfo:UpdateFreq(2.0)            -- change frequency
local val = lfo:Sine(t)        -- evaluate at time t

Shape Registry

Shapes are registered by name in Lfo.shapes. The modulator system looks them up via Lfo.shapeNames. To add a custom shape without modifying core code:

local Lfo = lovjRequire("lib/signals/lfo")

Lfo.registerShape("MyShape", function(self, t)
    local ph = math.fmod(self.frequency * (t + self.phase), 1)
    local y = -- your waveform math here, return [-1, 1]
    return y * SMath.b2n(self:isTriggerActive())
end)

Built-in shapes: Sine, Square, Triangle, RampUp, RampDown, SmoothRampUp, SmoothRampDown, Pulse, RandomSH.

Envelope

Linear ADSR (Attack-Decay-Sustain-Release) envelope.

local Envelope = lovjRequire("lib/signals/envelope")
local env = Envelope:new(attackTime, decayTime, sustainLevel, releaseTime)

Output

Returns values in [0, 1].

Method Description
Calculate(t) Composite ADSR output — use this one
Attack(t) Attack phase only
Decay(t, rlsCall) Decay phase only
Sustain(t) Sustain phase only
Release(t) Release phase only

Triggering

env:UpdateTrigger(gateOn)  -- true = gate on (attack), false = gate off (release)
local value = env:Calculate(t)

The envelope retriggers on each 0→1 gate transition.

Usage in Patches

local lfo = Lfo:new(1, 0)
local env = Envelope:new(0.1, 0.2, 0.5, 0.3)

function patch.update()
    patch:mainUpdate()
    local t = cfg_timers.globalTimer.T
    lfo:UpdateTrigger(true)
    env:UpdateTrigger(someTriggerCondition)
end

function patch.draw()
    local t = cfg_timers.globalTimer.T
    local wobble = lfo:Sine(t) * 20
    local brightness = env:Calculate(t)
    -- use wobble and brightness in drawing
end

Easing Curves

26 built-in easing curves are available for shaping transitions, morph interpolation, and sequencer per-step easing. See Easing & Interpolation for the full catalog and API.

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