add superdough package

packages/superdough/helpers.mjs

@@ -0,0 +1,70 @@
+import { getAudioContext } from './superdough.mjs';
+
+export function gainNode(value) {
+  const node = getAudioContext().createGain();
+  node.gain.value = value;
+  return node;
+}
+
+export const getOscillator = ({ s, freq, t }) => {
+  // make oscillator
+  const o = getAudioContext().createOscillator();
+  o.type = s || 'triangle';
+  o.frequency.value = Number(freq);
+  o.start(t);
+  //o.stop(t + duration + release);
+  const stop = (time) => o.stop(time);
+  return { node: o, stop };
+};
+
+// alternative to getADSR returning the gain node and a stop handle to trigger the release anytime in the future
+export const getEnvelope = (attack, decay, sustain, release, velocity, begin) => {
+  const gainNode = getAudioContext().createGain();
+  gainNode.gain.setValueAtTime(0, begin);
+  gainNode.gain.linearRampToValueAtTime(velocity, begin + attack); // attack
+  gainNode.gain.linearRampToValueAtTime(sustain * velocity, begin + attack + decay); // sustain start
+  // sustain end
+  return {
+    node: gainNode,
+    stop: (t) => {
+      //if (typeof gainNode.gain.cancelAndHoldAtTime === 'function') {
+      // gainNode.gain.cancelAndHoldAtTime(t); // this seems to release instantly....
+      // see https://discord.com/channels/779427371270275082/937365093082079272/1086053607360712735
+      //} else {
+      // firefox: this will glitch when the sustain has not been reached yet at the time of release
+      gainNode.gain.setValueAtTime(sustain * velocity, t);
+      //}
+      gainNode.gain.linearRampToValueAtTime(0, t + release);
+    },
+  };
+};
+
+export const getADSR = (attack, decay, sustain, release, velocity, begin, end) => {
+  const gainNode = getAudioContext().createGain();
+  gainNode.gain.setValueAtTime(0, begin);
+  gainNode.gain.linearRampToValueAtTime(velocity, begin + attack); // attack
+  gainNode.gain.linearRampToValueAtTime(sustain * velocity, begin + attack + decay); // sustain start
+  gainNode.gain.setValueAtTime(sustain * velocity, end); // sustain end
+  gainNode.gain.linearRampToValueAtTime(0, end + release); // release
+  // for some reason, using exponential ramping creates little cracklings
+  /* let t = begin;
+  gainNode.gain.setValueAtTime(0, t);
+  gainNode.gain.exponentialRampToValueAtTime(velocity, (t += attack));
+  const sustainGain = Math.max(sustain * velocity, 0.001);
+  gainNode.gain.exponentialRampToValueAtTime(sustainGain, (t += decay));
+  if (end - begin < attack + decay) {
+    gainNode.gain.cancelAndHoldAtTime(end);
+  } else {
+    gainNode.gain.setValueAtTime(sustainGain, end);
+  }
+  gainNode.gain.exponentialRampToValueAtTime(0.001, end + release); // release */
+  return gainNode;
+};
+
+export const getFilter = (type, frequency, Q) => {
+  const filter = getAudioContext().createBiquadFilter();
+  filter.type = type;
+  filter.frequency.value = frequency;
+  filter.Q.value = Q;
+  return filter;
+};