| /** | |
| * @param {number} frequency | |
| * @param {number} [duration] in seconds | |
| * @param {number} [wavetype] 0 (sine), 1 (triangle), 2 (saw), 3 (tan), 4 (noise) or 5 (square) | |
| * @param {number} [volume] | |
| */ | |
| function beep(frequency, duration = 0.1, wavetype = 1, volume = .5) { | |
| sfx([, 0, frequency, 0.01, duration, 0.01, wavetype], 0, volume) | |
| } | |
| /** | |
| * Get frequency of a note on a musical scale | |
| * | |
| * @param {number} semitoneOffset - How many semitones away from the root note | |
| * @param {number} [rootFrequency=220] - Frequency at semitone offset 0 | |
| * @returns {number} - The frequency of the note | |
| */ | |
| function notefreq(semitoneOffset, rootFrequency = 220) { | |
| return rootFrequency * (2 ** (semitoneOffset/12)); | |
| } | |
| /** | |
| * @param {number[][]} notes | |
| * @param {number} [gap] seconds between each note | |
| */ | |
| function melody(notes, gap = 0.1) { | |
| for (let i = 0; i < notes.length; i++) { | |
| const note = notes[i] || [0] | |
| let t = T + i * gap | |
| const handler = (dt) => { | |
| if (T >= t) { | |
| beep(...note) | |
| unlisten('update', handler) | |
| } | |
| } | |
| listen('update', handler) | |
| } | |
| } |
beep(440, 0.5) // play the frequency 440Hz for 0.5 secondmelody(
[
[notefreq(12), 0.1, 0, 0.3], // note=A, dur=0.1, wave=sine, volume=0.3
[notefreq(14), 0.1, 0, 0.5], // note=B, dur=0.1, wave=sine, volume=0.5
[notefreq(15), 0.1, 0, 0.6], // note=C, dur=0.1, wave=sine, volume=0.6
],
0.25 // wait 0.25 seconds between each note
)
Live Demo