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Move musical timing into music extension

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and use the stackframe timer, which improves timing accuracy.
This commit is contained in:
Eric Rosenbaum 2017-11-09 17:41:37 -05:00
parent 3fa1599b90
commit db3b0ca204
1 changed files with 46 additions and 9 deletions
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55
src/blocks/scratch3_music.js
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@ -3,6 +3,7 @@ const BlockType = require('../extension-support/block-type');
const Clone = require('../util/clone');
const Cast = require('../util/cast');
const MathUtil = require('../util/math-util');
const Timer = require('../util/timer');
/**
* An array of drum names, used in the play drum block.
@ -70,6 +71,13 @@ class Scratch3MusicBlocks {
*/
this.runtime = runtime;
/**
* The current tempo in beats per minute. The tempo is a global property of the project,
* not a property of each sprite, so it is not stored in the MusicState object.
* @type {number}
*/
this.tempo = 60;
this.drumMenu = this._buildMenu(drumNames);
this.instrumentMenu = this._buildMenu(instrumentNames);
}
@ -272,11 +280,10 @@ class Scratch3MusicBlocks {
* @property {number} BEATS - the duration in beats of the rest.
* @return {Promise} - a promise which will resolve at the end of the duration.
*/
restForBeats (args) {
restForBeats (args, util) {
let beats = Cast.toNumber(args.BEATS);
beats = this._clampBeats(beats);
if (typeof this.runtime.audioEngine === 'undefined') return;
return this.runtime.audioEngine.waitForBeats(beats);
this._waitForBeats(beats, util);
}
/**
@ -315,6 +322,39 @@ class Scratch3MusicBlocks {
return this.runtime.audioEngine.instrumentPlayer.loadInstrument(musicState.currentInstrument);
}
/**
* Convert a number of beats to a number of seconds, using the current tempo.
* @param {number} beats - number of beats to convert to secs.
* @return {number} seconds - number of seconds `beats` will last.
* @private
*/
_beatsToSec (beats) {
return (60 / this.tempo) * beats;
}
/**
* Wait for some number of beats.
* @param {number} beats - number of beats to wait for.
* @param {object} util - utility object provided by the runtime.
* @private
*/
_waitForBeats (beats, util) {
if (util.stackFrame.timer) {
const timeElapsed = util.stackFrame.timer.timeElapsed();
if (timeElapsed < util.stackFrame.duration * 1000) {
util.yield();
}
} else {
util.stackFrame.timer = new Timer();
util.stackFrame.timer.start();
util.stackFrame.duration = this._beatsToSec(beats);
if (util.stackFrame.duration <= 0) {
return;
}
util.yield();
}
}
/**
* Clamp a duration in beats to the allowed min and max duration.
* @param {number} beats - a duration in beats.
@ -342,8 +382,7 @@ class Scratch3MusicBlocks {
*/
changeTempo (args) {
const change = Cast.toNumber(args.TEMPO);
if (typeof this.runtime.audioEngine === 'undefined') return;
const tempo = change + this.runtime.audioEngine.currentTempo;
const tempo = change + this.tempo;
this._updateTempo(tempo);
}
@ -354,8 +393,7 @@ class Scratch3MusicBlocks {
*/
_updateTempo (tempo) {
tempo = MathUtil.clamp(tempo, Scratch3MusicBlocks.TEMPO_RANGE.min, Scratch3MusicBlocks.TEMPO_RANGE.max);
if (typeof this.runtime.audioEngine === 'undefined') return;
this.runtime.audioEngine.setTempo(tempo);
this.tempo = tempo;
}
/**
@ -363,8 +401,7 @@ class Scratch3MusicBlocks {
* @return {number} - the current tempo, in beats per minute.
*/
getTempo () {
if (typeof this.runtime.audioEngine === 'undefined') return;
return this.runtime.audioEngine.currentTempo;
return this.tempo;
}
}