proper dry wet + pull out noise to extra file

packages/superdough/noise.mjs

@@ -0,0 +1,51 @@
+import { drywet } from './helpers.mjs';
+
+// expects one of noises as type
+export function getNoiseOscillator(type = 'white', t) {
+  const ac = getAudioContext();
+  const bufferSize = 2 * ac.sampleRate;
+  const noiseBuffer = ac.createBuffer(1, bufferSize, ac.sampleRate);
+  const output = noiseBuffer.getChannelData(0);
+  let lastOut = 0;
+  let b0, b1, b2, b3, b4, b5, b6;
+  b0 = b1 = b2 = b3 = b4 = b5 = b6 = 0.0;
+
+  for (let i = 0; i < bufferSize; i++) {
+    if (type === 'white') {
+      output[i] = Math.random() * 2 - 1;
+    } else if (type === 'brown') {
+      let white = Math.random() * 2 - 1;
+      output[i] = (lastOut + 0.02 * white) / 1.02;
+      lastOut = output[i];
+    } else if (type === 'pink') {
+      let white = Math.random() * 2 - 1;
+      b0 = 0.99886 * b0 + white * 0.0555179;
+      b1 = 0.99332 * b1 + white * 0.0750759;
+      b2 = 0.969 * b2 + white * 0.153852;
+      b3 = 0.8665 * b3 + white * 0.3104856;
+      b4 = 0.55 * b4 + white * 0.5329522;
+      b5 = -0.7616 * b5 - white * 0.016898;
+      output[i] = b0 + b1 + b2 + b3 + b4 + b5 + b6 + white * 0.5362;
+      output[i] *= 0.11;
+      b6 = white * 0.115926;
+    }
+  }
+
+  const o = ac.createBufferSource();
+  o.buffer = noiseBuffer;
+  o.loop = true;
+  o.start(t);
+  return {
+    node: o,
+    stop: (time) => o.stop(time),
+  };
+}
+
+export function getNoiseMix(inputNode, wet, t) {
+  const noiseOscillator = getNoiseOscillator('pink', t);
+  const noiseMix = drywet(inputNode, noiseOscillator.node, wet);
+  return {
+    node: noiseMix,
+    stop: (time) => noiseOscillator?.stop(time),
+  };
+}