1 files changed, 97 insertions, 0 deletions
diff --git a/client/lib/bandpass.js b/client/lib/bandpass.js
new file mode 100644
index 0000000..3e1ed16
--- /dev/null
+++ b/client/lib/bandpass.js
@@ -0,0 +1,97 @@
+/**
+ * Bandpassed noise organ
+ * @module lib/bandpass.js;
+ */
+
+import Tone from "tone";
+import { roundInterval } from "./util";
+
+let root = 440;
+
+let oscillators = {};
+let output;
+let lastPlayed;
+let noise;
+
+function load(out) {
+  output = out;
+}
+function isPlaying(interval) {
+  const rounded = roundInterval(interval);
+  const osc = oscillators[rounded];
+  return osc && osc.playing;
+}
+function play(interval) {
+  if (!output) {
+    return;
+  }
+  if (!noise) {
+    noise = new Tone.Noise().start();
+  }
+  const rounded = roundInterval(interval);
+  const osc = (oscillators[rounded] = oscillators[rounded] || {});
+  if (!osc.el) {
+    osc.interval = interval;
+    osc.el = new Tone.Filter(interval * root, "bandpass");
+    osc.el.Q.value = 100;
+  }
+  noise.connect(osc.el);
+  osc.el.connect(output);
+  osc.playing = true;
+  lastPlayed = osc;
+  return osc;
+}
+
+function pause(interval) {
+  const rounded = roundInterval(interval);
+  if (!oscillators[rounded]) return;
+  const osc = (oscillators[rounded] = oscillators[rounded] || {});
+  osc.el.disconnect(output);
+  noise.disconnect(osc.el);
+  osc.playing = false;
+  return osc;
+}
+function toggle(interval) {
+  const rounded = roundInterval(interval);
+  const osc = (oscillators[rounded] = oscillators[rounded] || {});
+  if (osc && osc.playing) {
+    pause(interval);
+  } else {
+    play(interval);
+  }
+}
+
+function setRoot(newRoot) {
+  root = newRoot;
+  for (const osc of Object.values(oscillators)) {
+    osc.el.frequency.value = osc.interval * newRoot;
+  }
+}
+function stop() {
+  for (const osc of Object.values(oscillators)) {
+    if (!osc.playing) {
+      continue;
+    }
+    osc.el.disconnect(output);
+    noise.disconnect(osc.el);
+    osc.playing = false;
+    delete osc.el;
+  }
+  oscillators = {};
+}
+function getPlaying() {
+  return Object.values(oscillators)
+    .filter((osc) => osc.playing)
+    .map((osc) => osc.interval);
+}
+
+export default {
+  load,
+  isPlaying,
+  getPlaying,
+  play,
+  pause,
+  toggle,
+  stop,
+  setRoot,
+};