add superdough package

packages/superdough/feedbackdelay.mjs

@@ -0,0 +1,31 @@
+if (typeof DelayNode !== 'undefined') {
+  class FeedbackDelayNode extends DelayNode {
+    constructor(ac, wet, time, feedback) {
+      super(ac);
+      wet = Math.abs(wet);
+      this.delayTime.value = time;
+
+      const feedbackGain = ac.createGain();
+      feedbackGain.gain.value = Math.min(Math.abs(feedback), 0.995);
+      this.feedback = feedbackGain.gain;
+
+      const delayGain = ac.createGain();
+      delayGain.gain.value = wet;
+      this.delayGain = delayGain;
+
+      this.connect(feedbackGain);
+      this.connect(delayGain);
+      feedbackGain.connect(this);
+
+      this.connect = (target) => delayGain.connect(target);
+      return this;
+    }
+    start(t) {
+      this.delayGain.gain.setValueAtTime(this.delayGain.gain.value, t + this.delayTime.value);
+    }
+  }
+
+  AudioContext.prototype.createFeedbackDelay = function (wet, time, feedback) {
+    return new FeedbackDelayNode(this, wet, time, feedback);
+  };
+}