Glossary

Short definitions for the terms you’ll encounter across guides and reference pages. Entries are alphabetical.

A

Accumulator — the single render target that every source and effect operates against during a frame. The chain walks top to bottom; sources composite onto the accumulator; effects transform it in place. See The Chain Model.

Action Button — a one-touch macro attached to a node’s parameter. Action buttons can snapshot-recall, step through values, or trigger spring-physics animations. See the Performing Live guide.

Ableton Link — a network protocol for sharing tempo and phase between music apps on a LAN. Lightbridge supports Link as a beat source, letting you sync to DJ software or live instruments automatically.

Auto Mode — the default output mode where parameter changes go to live immediately. Contrast with Hold Mode.

Auto Sync — a beat source that listens to the audio input and detects BPM automatically using a beat-tracking algorithm (BTT WASM module).

B

Bar — four beats in 4/4 time. The beat clock tracks the current bar index within the phrase.

Beat Clock — the shared tempo and phase source used by every beat-synced modulation. Anchor-based, so BPM changes don’t produce phase jumps. See Audio & Beat.

Beat Division — for beat-synced LFOs and beat sources, how many beats per cycle. 1 = quarter note, 4 = bar, 0.25 = sixteenth, and so on.

Beat LFO — informal term for an LFO source with a non-zero beat division. Not a separate source type — see lfo source in the Modulation concept.

Beat Source — either one of the four BPM sources (Fixed, Tap, Auto Sync, Ableton Link), or the “Beat” option in a modulation’s source selector, which reads the beat counter directly.

Blend Mode — how a source’s pixels combine with the accumulator. Nine modes available. See the Blend Modes reference.

BPM — beats per minute. Always clamped to [20, 300].

BTT — the beat tracking library Lightbridge uses for Auto Sync, compiled from C to WASM and run in a web worker.

C

Chain — the ordered list of nodes (sources, effects, and groups) that produces the composition. Nodes walk top-to-bottom into a single accumulator. See The Chain Model.

Chain Effect — an effect node placed directly in the chain, as opposed to being attached to a source. Applies to the entire accumulator from its position onward (or, inside a group, to that group’s sub-accumulator).

Chain Node — a single entry in the chain. Always either a source, an effect, or a group.

Colour Group — metadata on a parameter that identifies which logical colour it belongs to on its source. Params sharing a colour group are treated as one unit by the palette. Example values: color, bg, color1, color2.

Colour Role — metadata on a parameter identifying which component of an HSB colour it represents. Exactly one of h, s, b.

Composite — (verb) the step where a source’s pixels are blended into the accumulator using its blend mode and opacity.

Control Point — a vertex position on a projection mapping surface. Corner-pin has four; a subdivided mesh has (N+1) × (M+1).

Controller Mirror — the renderer UI panel that shows a live layout of your connected MIDI controller. Drag parameters onto controller elements to bind them.

Corner-Pin — a projection mapping surface with a single 1×1 mesh — four corners, no subdivisions. Good for flat screens; not for curved surfaces.

Curve — the response curve stage in a modulation. Sixteen presets plus custom editing. See Modulation Curves.

D

Delta Gating — a performance optimisation where overlays only push a new value if it changed by more than 1e-5. Applies to palette and modulation overlays.

Dual Canvas — the preview + live canvas pair in the main window. See Output Visuals.

Dumb Renderer — the output window’s role in the pipeline: it receives already-overlaid params from the main window via IPC and renders them, running no modulation or audio of its own.

E

Edge Blend — per-edge blend zones on a projection mapping surface, used for multi-projector overlap. Configurable width, gamma, and power.

Effect — a chain node that transforms the accumulator rather than producing new content. Has mix, no blendMode or opacity.

Envelope Follower — the audio-engineering name for Lightbridge’s Reactivity stage. See Reactivity.

F

Feedback — the temporal pass at the end of the chain that mixes the previous frame into the current one. Produces trails, echoes, and other temporal effects.

FFT — Fast Fourier Transform. The audio pipeline’s first step, converting time-domain audio into frequency-domain magnitudes that get reduced to the six bands.

Fixed BPM — a beat source where you type the tempo directly.

Focus Mode — a fullscreen view of the live canvas, triggered with F. Hides all panels for a clean view of the output.

Group — a chain node that contains its own mini-chain. Children render into a sub-accumulator and composite into the parent chain like a source, so effects inside a group are scoped to that group. Groups carry opacity and a blend mode, can nest up to four levels deep, and are entered via double-click (or Enter Group). See Groups.

H

Hold Mode — the output mode where the live canvas is frozen while you edit preview. Toggled with H; commit preview to live with G. See Performing Live.

HSB — hue, saturation, brightness — the colour model Lightbridge uses for swatches and colour params. (Not HSL; not RGB.)

Hue Offset — a per-palette global hue rotation applied to all swatches at overlay time. Modulate this to rotate the whole palette through the colour wheel.

I

IPC — inter-process communication, specifically between the Electron main process and renderer processes, and between renderer processes (main window ↔ output window ↔ mapping editor).

Input Rect — the normalized [0,1] region of the composition that a projection mapping surface samples from. Defaults to the full composition.

L

LFO — low-frequency oscillator. A modulation source that generates a ramp signal either at a Hertz rate (free-running) or a beat division (beat-synced).

Live Canvas — the output the audience sees. Paired with the preview canvas in the main window.

M

Mapping Editor — a separate window (?mapping=1) for editing projection mapping surfaces, opened from the Map button in the Output Mode Bar.

Mesh Divisions — how many cells a projection mapping surface is cut into. 1×1 is corner-pin; higher values produce more control points for curved surfaces.

MIDI CC — MIDI Continuous Controller. The main way to bind a physical knob or fader to a parameter in Lightbridge. CCs override every other layer in the priority chain.

Mix — the per-effect parameter in [0, 1] that crossfades between dry (accumulator unchanged) and wet (effect applied at full strength).

Modulation — a complete route from a signal source (audio, LFO, or beat) to a parameter, with shaping stages (curve, direction, range) baked in. Each parameter can have at most one modulation. Created via the right-click context menu on any parameter slider. See The Modulation System. In the engine source this is called a “ModSlot” for historical reasons.

Modulation — the process of driving a parameter with a time-varying signal instead of a fixed slider value. Tier 2 in the priority chain.

N

Node — see Chain Node.

O

Opacity — per-source composite strength in [0, 1]. 1.0 is fully opaque, 0.0 is invisible. Applies during the composite stage.

Output Config — the data model for projection mapping, containing one or more screens, each with one or more surfaces. Saved in the show file.

Output Screen — one entry in the output config, assigned to a physical display.

Output Surface — a single warped quad or mesh within a screen. Has control points, input rect, edge blend, brightness, and gamma.

Output Window — a secondary window that displays live content. Fed by the main window frame by frame. See Output Visuals.

Overlay — a function that takes chain nodes and returns a modified version with some layer’s values substituted in. The palette and modulation systems both run as overlays. See Parameter Priority.

P

Palette — the per-set colour system. Seven HSB swatches, channel bindings from source colour groups to swatches, and a master hue offset. See The Palette System.

Palette Channel — the binding from a source’s colour group to a specific swatch index (or Off).

Parameter Priority — the order in which the five layers (MIDI, Modulation, Palette, Slider, Default) are resolved to produce a final value. See reference.

ParamDef — a parameter’s definition: key, label, range, default, unit, colour metadata, extendability, etc. Lives in packages/engine/src/params/ParamDefs.ts.

Performance Set — a named collection of chain + parameters + modulations + palette + action buttons. A show file contains one or more sets. Switching sets is the primary live transition tool. See the Performance Sets guide.

Per-Source Effect — an effect attached to a specific source (via sourceEffects), applied before the source is composited onto the accumulator. Contrast with chain effects.

Phase — fractional position within a beat or a modulation cycle, in [0, 1).

Phase Lock — the property of beat-synced modulations that they align with the global beat grid rather than their own creation time. Two beat-synced LFOs started thirty seconds apart still hit beat zero together.

Phrase — eight bars (thirty-two beats). The highest-level structural unit tracked by the beat clock.

Preset — a saved parameter snapshot. Sources and effects have their own preset types; modulation curves also have presets.

Preview Canvas — the top canvas in the main window, where you build the next look while the live canvas plays. Auto mode keeps them in sync; hold mode freezes live while preview updates.

Pulse — a boolean that is true for exactly one frame on a beat boundary. Useful for triggers.

R

Range Mapping — the rangeMin / rangeMax stage at the end of a modulation, which scales the shaped [0, 1] signal into the parameter’s target range.

Reactivity — the audio-modulation stage that traces the overall loudness shape of an audio signal so a parameter driven by audio reacts to the swell of a sound rather than every tiny spike. Controlled by Reaction Speed / Decay Speed globally in the Reactivity Controls panel, or Attack / Release per-modulation inside the mod panel. Audio-engineering literature calls this an “envelope follower”; Lightbridge calls it reactivity to match the panel name.

Render Pipeline — the orchestrator in the graphics package that walks the chain, renders sources, applies effects, runs feedback, and outputs the final frame.

Resync — a hard reset of the beat clock to beat 1, bar 1, phrase 1. Separate from tap tempo.

S

Set — see Performance Set.

Show File — the single file (.lbshow, JSON format) that stores everything about your project: sets, chains, modulations, palettes, controller profiles, mapping, action buttons.

Slot — the engine’s internal name for a modulation. See Modulation.

Source — a chain node that generates content. Has blendMode, opacity, and optional sourceEffects. Ignores mix.

Source Effect — see Per-Source Effect.

Source Transform — the per-source translate/rotate/scale/zoom stage applied at the pipeline level via SourceTransform.ts. Params: t_x, t_y, t_rz, t_scale, t_zoom. Universal across all sources.

Spring Physics — the math CustomButton uses for smooth animated transitions: a critically-damped or lag-and-overshoot spring that moves a parameter toward a target value over time.

Sub-accumulator — the render target a group renders into. Identical model to the top-level accumulator, scoped to the group’s children, and handed back to the parent chain as a single image once the group’s walk ends. See The Chain Model.

Swatch — one entry in a palette. Holds a single {h, s, b} colour.

Syphon / Spout — GPU texture-sharing protocols for macOS and Windows respectively. Lightbridge scaffolds support via Electron’s useSharedTexture but the native addons are not yet shipped.

T

Tap Tempo — a beat source where you tap a button in rhythm with the music. Averages up to eight recent taps; history resets after a three-second gap. Does not reset phase.

Target — the parameter a modulation drives. Implicit — you right-click the parameter slider you want to modulate, and it becomes the target.

Total Beats — the monotonic count of fractional beats since the session started. Used by beat-synced LFOs for phase lock.

Transform — see Source Transform.

W

WASM — WebAssembly. Lightbridge ships BTT (beat tracking) as a WASM module loaded in a web worker for Auto Sync.

Related

• The Chain Model — the central concept most of these terms orbit.
• Parameter Priority — how the layers above interact.