Add a basic selection of instruments from the MIDI and chiptune categories

src/audio.ts

@@ -0,0 +1,71 @@
+import * as tone from "tone";
+import { assertNever, notes } from "./index";
+import { instrumentData } from "./data";
+
+function setSamplerRelease(sampler: tone.Sampler, instrument: string) {
+    const instrumentDuration = instrumentData[instrument]["duration"];
+
+    switch (instrumentDuration) {
+        case "instant":
+            sampler.release = 0.05;
+            break;
+        case "mini":
+            sampler.release = 0.125;
+            break;
+        case "short":
+            sampler.release = 0.25;
+            break;
+        case "mid":
+            sampler.release = 0.4;
+            break;
+        case "long":
+            sampler.release = 1;
+            break;
+        case "extended":
+            sampler.release = 1.5;
+            break;
+        case "mega":
+            sampler.release = 5;
+            break;
+        case "constant":
+            sampler.release = 30;
+            break;
+        case "infinite":
+            sampler.release = 0.1;
+            break;
+        default:
+            assertNever(instrumentDuration);
+    }
+}
+
+function setSamplerCurve(sampler: tone.Sampler) {
+    (sampler as any).curve = "linear";
+}
+
+export function getSampler(
+    instrument: string,
+    extension: string = "ogg",
+    baseUrl: string = "/bosca-ceoil-js/audio/"
+): tone.Sampler {
+    let samples: { [key: string]: string } = {};
+    for (const note of notes) {
+        samples[note] = `${instrument}/${note.toLowerCase()}.${extension}`;
+    }
+    let sampler = new tone.Sampler(samples, undefined, baseUrl);
+    setSamplerCurve(sampler);
+    setSamplerRelease(sampler, instrument);
+    return sampler;
+}
+
+export function changeSampler(
+    sampler: tone.Sampler,
+    instrument: string,
+    extension: string = "ogg",
+): tone.Sampler {
+    for (const note of notes) {
+        sampler.add(note, `${instrument}/${note.toLowerCase()}.${extension}`);
+    }
+    setSamplerCurve(sampler);
+    setSamplerRelease(sampler, instrument);
+    return sampler;
+}

src/data.ts

@@ -0,0 +1,3 @@
+import { InstrumentData } from "./index";
+
+export const instrumentData: InstrumentData = require("../instruments.yaml");

src/index.ts

@@ -1,17 +1,22 @@
-import * as tone from 'tone';
-
-const notes = ["C1", "C2", "C3", "C4", "C5", "C6", "C7", "C8", "C9"];
-
-export function getSampler(
-    instrument: string,
-    extension: string = "flac",
-    baseUrl: string = "/bosca-ceoil-js/audio/"
-): tone.Sampler {
-    let samples: { [key: string]: string } = {};
-    for (const note of notes) {
-        samples[note] = `${instrument}/${note.toLowerCase()}.${extension}`;
-    }
-    let sampler = new tone.Sampler(samples, undefined, baseUrl);
-    (sampler as any).curve = "linear";
-    return sampler;
+export function assertNever(x: never): never {
+    throw new Error(`Unexhaustive condition leading to value: ${x}`);
 }
+
+// Durations:
+// - Constant means that the sound plays for the same amount of time
+//   regardless of the length of the note in Bosca Ceoil.
+// - Infinite means that the sound plays for however arbitrarily long
+//   the Bosca Ceoil note is.
+// - The others are finite times, meaning that the sound will play up to
+//   a max time, but after that point, it will go silent regardless of how
+//   long the note is in Bosca Ceoil.
+export interface Instrument {
+    index: number;
+    duration: "instant" | "mini" | "short" | "mid" | "long" | "extended" | "mega" | "constant" | "infinite";
+    release: number;
+    category: Array<string>;
+}
+
+export type InstrumentData = { [key: string]: Instrument };
+
+export const notes = ["C1", "C2", "C3", "C4", "C5", "C6", "C7", "C8", "C9"];

src/player.ts

@@ -1,5 +1,5 @@
 import * as tone from 'tone';
-import { getSampler } from "./index";
+import { changeSampler, getSampler } from "./audio";
 const dialogPolyfill = require("dialog-polyfill");
 
 let playing = false;
@@ -25,6 +25,7 @@ interface Note {
     scheduledEvent: number | null;
 }
 
+let instrumentName = "midi.piano1";
 let sampler = getSampler("midi.piano1");
 let patterns: { [key: number]: { [key: string]: Array<Note> } } = {};
 for (const chord of chords) {
@@ -54,6 +55,20 @@ function resumeAudioContext() {
     }
 }
 
+// mdl-selectfield doesn't play nice with custom onchange event listeners,
+// so we use this to handle instrument changes instead.
+function setInstrumentLoop(instrumentField: HTMLSelectElement) {
+    setInstrument(instrumentField);
+    setTimeout(() => { setInstrumentLoop(instrumentField); }, 250);
+}
+
+function setInstrument(instrumentField: HTMLSelectElement) {
+    if (instrumentName !== instrumentField.value) {
+        instrumentName = instrumentField.value;
+        changeSampler(sampler, instrumentField.value);
+    }
+}
+
 function setBpm() {
     let bpmField = document.getElementById("bpm");
     if (bpmField !== null && bpmField instanceof HTMLInputElement) {
@@ -247,6 +262,11 @@ function onLoad() {
         }
     }
 
+    let instrumentField = document.getElementById("instruments");
+    if (instrumentField !== null && instrumentField instanceof HTMLSelectElement) {
+        setInstrumentLoop(instrumentField);
+    }
+
     let bpmField = document.getElementById("bpm");
     if (bpmField !== null) {
         bpmField.addEventListener("change", setBpm);