homepage/content/toys/starship/starship.js

64 lines
1.7 KiB
JavaScript

function whiteNoise(audioCtx) {
var bufferSize = 17 * audioCtx.sampleRate,
noiseBuffer = audioCtx.createBuffer(1, bufferSize, audioCtx.sampleRate),
output = noiseBuffer.getChannelData(0);
for (var i = 0; i < bufferSize; i++) {
output[i] = Math.random() * 2 - 1;
}
var whiteNoise = audioCtx.createBufferSource();
whiteNoise.buffer = noiseBuffer;
whiteNoise.loop = true;
whiteNoise.start(0);
return whiteNoise;
}
function bandpassFilter(audioCtx, freq, gain) {
var filt = audioCtx.createBiquadFilter();
filt.type = "bandpass";
filt.frequency.value = freq;
filt.gain.value = gain;
return filt;
}
function init() {
var audioCtx = new window.AudioContext();
var synth = whiteNoise(audioCtx);
var filterA = bandpassFilter(audioCtx, 100, 20);
var filterB = bandpassFilter(audioCtx, 50, 20);
var gainA = audioCtx.createGain();
whiteNoise(audioCtx).connect(filterA);
filterA.connect(filterB);
filterB.connect(gainA);
gainA.connect(audioCtx.destination);
audioCtx.suspend();
function setFade() {
var faderPos = document.querySelector("#fader").value;
gainA.gain.value = faderPos;
}
document.querySelector("#fader").addEventListener("input", setFade);
setFade();
let play = document.querySelector("#play");
play.addEventListener("click", e => {
if (audioCtx.state == "running") {
audioCtx.suspend();
play.textContent = "▶️️";
} else {
audioCtx.resume();
play.textContent = "⏸️";
}
});
if ("serviceWorker" in navigator) {
navigator.serviceWorker.register("sw.js");
}
}
if (document.readyState === "loading") {
document.addEventListener("DOMContentLoaded", init);
} else {
init();
}