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var midiLoaded = false;
function loadMIDI() {
MIDI.loadPlugin({
soundfontUrl: "/static/trading-in-the-rain/soundfont/",
instrument: "acoustic_grand_piano",
onprogress: (state, progress) => {
console.log("MIDI loading...", progress*100, "%");
},
onsuccess: () => {
console.log("MIDI is ready to be used");
MIDI.setVolume(0, 127);
midiLoaded = true;
},
});
}
function MusicBox(priceDist, volumeDist) {
this.priceDist = priceDist;
this.volumeDist = volumeDist;
// clamp the keyboard so we're not using the very low notes, they don't sound
// good.
const noteRange = {
//low: 21,
//low: 36, // C2
low: 60, // C4, middle C
high: 108
};
function makeScale(tpl) {
tplObj = {};
for (i in tpl) {
tplObj[tpl[i]] = true;
}
let scale = [];
for (let note=noteRange.low; note<=noteRange.high; note++) {
let key = MIDI.noteToKey[note].replace(/\d+$/, "");
if (tplObj[key]) {
scale.push(note);
}
}
return scale;
}
//this.scale = makeScale(["C", "D", "E", "F", "G", "A", "B"]); // cMajor
//this.scale = makeScale(["D", "E", "Gb", "G", "A", "Db"]); //dMajor
//this.scale = makeScale(["C", "D", "E", "G", "A"]); // cMajor pentatonic
this.scale = makeScale(["F", "G", "A", "C", "D"]); // fMajor pentatonic
this.playNote = (note, holdFor) => {
if (!midiLoaded) return;
let velocity = 127;
MIDI.noteOn(0, note, velocity, 0);
MIDI.noteOff(0, note, holdFor);
};
this.playTrades = (trades) => {
if (this.priceDist.length == 0) return;
for (let i in trades) {
let noteIdx = this.priceDist.distribute(trades[i].price, 0, this.scale.length-1);
noteIdx = Math.round(noteIdx);
let holdFor = 0.25 + this.volumeDist.distribute(trades[i].volume, 0, 1.75);
let note = this.scale[noteIdx];
this.playNote(note, holdFor);
}
};
}
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