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resources/app/client-esm/audio/convolver.mjs

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+import Sound from "./sound.mjs";
+
+/**
+ * A sound effect which applies a convolver filter.
+ * The convolver effect splits the input sound into two separate paths:
+ * 1. A "dry" node which is the original sound
+ * 2. A "wet" node which contains the result of the convolution
+ * This effect mixes between the dry and wet channels based on the intensity of the reverb effect.
+ * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/ConvolverNode}
+ * @alias foundry.audio.ConvolverFilterEffect
+ */
+export default class ConvolverEffect extends ConvolverNode {
+  /**
+   * A ConvolverEffect is constructed by passing the following parameters.
+   * @param {AudioContext} context      The audio context required by the ConvolverNode
+   * @param {object} [options]          Additional options which modify the ConvolverEffect behavior
+   * @param {string} [options.impulseResponsePath]  The file path to the impulse response buffer to use
+   * @param {number} [options.intensity]            The initial intensity of the effect
+   */
+  constructor(context, {impulseResponsePath="sounds/impulse-responses/ir-full.wav", intensity=5, ...options}={}) {
+    super(context, options);
+    this.#impulseResponsePath = impulseResponsePath;
+    this.#intensity = intensity;
+    this.#dryGain = context.createGain();
+    this.#wetGain = context.createGain();
+    this.update();
+  }
+
+  /**
+   * The identifier of the impulse response buffer currently used.
+   * The default impulse response function was generated using https://aldel.com/reverbgen/.
+   * @type {string}
+   */
+  #impulseResponsePath;
+
+  /**
+   * A GainNode which mixes base, non-convolved, audio playback into the final result.
+   * @type {GainNode}
+   */
+  #dryGain;
+
+  /**
+   * A GainNode which mixes convolved audio playback into the final result.
+   * @type {GainNode}
+   */
+  #wetGain;
+
+  /**
+   * Flag whether the impulse response buffer has been loaded to prevent duplicate load requests.
+   * @type {boolean}
+   */
+  #loaded = false;
+
+  /* -------------------------------------------- */
+
+  /**
+   * Adjust the intensity of the effect on a scale of 0 to 10.
+   * @type {number}
+   */
+  get intensity() {
+    return this.#intensity;
+  }
+
+  set intensity(value) {
+    this.update({intensity: value});
+  }
+
+  #intensity;
+
+  /* -------------------------------------------- */
+
+  /**
+   * Update the state of the effect node given the active flag and numeric intensity.
+   * @param {object} options            Options which are updated
+   * @param {number} [options.intensity]  A new effect intensity
+   */
+  update({intensity} = {}) {
+    if ( Number.isFinite(intensity) ) this.#intensity = Math.clamp(intensity, 1, 10);
+
+    // Load an impulse response buffer
+    if ( !this.#loaded ) {
+      const irSound = new Sound(this.#impulseResponsePath, {context: this.context});
+      this.#loaded = true;
+      irSound.load().then(s => this.buffer = s.buffer);
+    }
+
+    // Set mix of wet and dry gain based on reverb intensity
+    this.#wetGain.gain.value = 0.2 + Math.sqrt(this.#intensity / 10); // [0.2, 1.2]
+    this.#dryGain.gain.value = Math.sqrt((11 - this.#intensity) / 10);
+  }
+
+  /* -------------------------------------------- */
+
+  /** @override */
+  disconnect(...args) {
+    this.#wetGain.disconnect();
+    this.#dryGain.disconnect();
+    return super.disconnect(...args);
+  }
+
+  /* -------------------------------------------- */
+
+  /** @override */
+  connect(destinationNode, ...args) {
+    super.connect(this.#wetGain, ...args);
+    this.#dryGain.connect(destinationNode);
+    this.#wetGain.connect(destinationNode);
+    return destinationNode;
+  }
+
+  /* -------------------------------------------- */
+
+  /**
+   * Additional side effects performed when some other AudioNode connects to this one.
+   * This behavior is not supported by the base WebAudioAPI but is needed here for more complex effects.
+   * @param {AudioNode} sourceNode      An upstream source node that is connecting to this one
+   */
+  onConnectFrom(sourceNode) {
+    sourceNode.connect(this.#dryGain);
+  }
+}