Documentation Index
Fetch the complete documentation index at: https://mintlify.com/mbeckham4-hub/Rudi-Foodi/llms.txt
Use this file to discover all available pages before exploring further.
Rudi Foodi has no audio files — all music and sound effects are synthesized in real time using the Web Audio API’s oscillators and gain nodes. The entire audio engine lives in a single audio state object, four persistent oscillator nodes, and a handful of functions that schedule frequency transitions and fire one-shot beeps. The result is a surprisingly musical score that adapts to the current level and Zoomies state without loading a single .mp3.
The audio Object
All audio state is held in one plain object defined near the top of the script:
const audio = {
ctx: null, // AudioContext, created on first user gesture
ready: false, // true after initAudio() runs
musicGain: null, // GainNode controlling music volume
bassOsc: null, // Persistent sine oscillator (bass root note)
padOsc1: null, // Persistent triangle oscillator (chord mid)
padOsc2: null, // Persistent triangle oscillator (chord top)
melodyOsc: null, // Persistent square oscillator (melody lead)
musicInterval: null, // setInterval ID for chord cycling
melodyInterval: null, // setTimeout ID for melody note sequencing
currentTheme: -1 // Index into musicThemes, -1 = stopped
};
fxGain node — sound effects connect directly to ctx.destination via per-beep gain nodes that are created and discarded on every call to beep().
initAudio()
Browser autoplay policy forbids creating an AudioContext before a user gesture. The game defers initialization with a one-time pointerdown listener:
window.addEventListener("pointerdown", initAudio, { once: true });
initAudio() creates the context, builds the four persistent oscillators, connects them all through musicGain to ctx.destination, and starts them running silently at near-zero gain:
function initAudio() {
if (audio.ready) return;
audio.ctx = new (window.AudioContext || window.webkitAudioContext)();
audio.musicGain = audio.ctx.createGain();
audio.musicGain.gain.value = 0.00001;
audio.musicGain.connect(audio.ctx.destination);
audio.bassOsc = audio.ctx.createOscillator(); // type: "sine"
audio.padOsc1 = audio.ctx.createOscillator(); // type: "triangle"
audio.padOsc2 = audio.ctx.createOscillator(); // type: "triangle"
audio.melodyOsc = audio.ctx.createOscillator(); // type: "square"
// ... set types, initial frequencies, connect to musicGain, start all
audio.ready = true;
}
setTargetAtTime() frequency ramps rather than start/stop cycles, which avoids click artifacts.
Music Themes
The musicThemes array contains 10 entries. Each entry describes a complete musical environment for a pair of levels:
const musicThemes = [
{
chords: [
[55, 146.83, 196], // chord 0: A1 – D3 – G3
[65.41, 174.61, 220], // chord 1: C2 – F3 – A3
[73.42, 196, 246.94], // chord 2: D2 – G3 – B3
[49, 130.81, 174.61] // chord 3: G1 – C3 – F3
],
melody: [220, 246.94, 261.63, 293.66, 261.63, 246.94, 220, 196],
speed: 520 // ms between melody note steps
},
// ... 9 more themes
];
speed controls the tempo in milliseconds between melody steps; faster themes (e.g., 250 ms) feel urgent and energetic, slower ones (e.g., 700 ms) feel atmospheric.
applyLevelMusic(level)
applyLevelMusic is called by spawnLevel whenever a new level begins. It selects the theme by level index (wrapping every 10 levels), checks if the theme is already playing to avoid unnecessary restarts, then sets up two independent timers:
function applyLevelMusic(level) {
if (!audio.ready) return;
const themeIndex = (level - 1) % musicThemes.length;
if (audio.currentTheme === themeIndex) return;
audio.currentTheme = themeIndex;
audio.musicGain.gain.setTargetAtTime(0.022, audio.ctx.currentTime, 0.08);
if (audio.musicInterval) clearInterval(audio.musicInterval);
if (audio.melodyInterval) clearInterval(audio.melodyInterval);
const data = musicThemes[themeIndex];
let chordIndex = 0, melodyIndex = 0;
// Chord cycle: setInterval at 2400ms
audio.musicInterval = setInterval(() => {
const chord = data.chords[chordIndex % data.chords.length];
chordIndex++;
audio.bassOsc.frequency.setTargetAtTime(chord[0], audio.ctx.currentTime, 0.5);
audio.padOsc1.frequency.setTargetAtTime(chord[1], audio.ctx.currentTime, 0.5);
audio.padOsc2.frequency.setTargetAtTime(chord[2], audio.ctx.currentTime, 0.5);
}, 2400);
// Melody: recursive setTimeout, tempo-aware
function tickMelody() {
if (audio.currentTheme !== themeIndex) return;
const note = data.melody[melodyIndex % data.melody.length];
melodyIndex++;
audio.melodyOsc.frequency.setTargetAtTime(note, audio.ctx.currentTime, 0.08);
audio.melodyInterval = setTimeout(tickMelody, zoomLocked ? data.speed * 0.48 : data.speed);
}
tickMelody();
}
When Zoomies is active, the melody timer fires at data.speed * 0.48 — slightly more than double speed. This creates an audible tempo surge that reinforces the frantic energy of a full-speed run.
setTargetAtTime time constant of 0.5 seconds, which produces a slow, smooth pitch glide between chords. The melody oscillator uses 0.08 seconds — a much faster attack — giving the lead a plucky, articulated feel.
beep(freq, duration, type, volume)
Sound effects use short-lived one-shot oscillator → gain pairs that connect directly to ctx.destination:
function beep(freq, duration, type, volume) {
if (!audio.ready) return;
const osc = audio.ctx.createOscillator();
const gain = audio.ctx.createGain();
osc.type = type || "sine";
osc.frequency.value = freq || 440;
gain.gain.value = volume || 0.06;
osc.connect(gain);
gain.connect(audio.ctx.destination);
osc.start();
gain.gain.exponentialRampToValueAtTime(0.001, audio.ctx.currentTime + (duration || 0.1));
osc.stop(audio.ctx.currentTime + (duration || 0.1));
}
osc.stop(), the browser garbage-collects both nodes automatically.
Sound Effect Reference
| Event | freq | duration | type | volume |
|---|
| Treat collected by Rudi | 340 | 0.08 | "triangle" | 0.05 |
| Treat collected by clone | 190 | 0.12 | "sine" | 0.04 |
| Game start | 330 | 0.08 | "triangle" | 0.08 |
| Zoomies on | 140 | 0.08 | "triangle" | 0.05 |
| Zoomies off | 90 | 0.08 | "triangle" | 0.05 |
| Fly-away start | 440 | 0.2 | "triangle" | 0.08 |
| Meteor incoming | 80 | 1.4 | "sawtooth" | 0.12 |
| Explosion | 18 | 2.8 | "sawtooth" | 0.24 |
stopMusic()
stopMusic() clears both timers, resets currentTheme, and ramps musicGain to near-zero with a fast exponential decay:
function stopMusic() {
if (!audio.ready) return;
if (audio.musicInterval) clearInterval(audio.musicInterval);
if (audio.melodyInterval) clearInterval(audio.melodyInterval);
audio.musicInterval = null;
audio.melodyInterval = null;
audio.currentTheme = -1;
audio.musicGain.gain.setTargetAtTime(0.00001, audio.ctx.currentTime, 0.04);
}
0.00001 (rather than 0) is required because exponentialRampToValueAtTime cannot target 0 — zero is not representable on an exponential curve. The time constant 0.04 produces a fast but audibly smooth fade-out.
stopMusic() is called when the player returns to the main menu via resetGameToMenu().