1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
/**
* Relabi event generator
*/
import * as Tone from "tone";
import RelabiCanvas from "./canvas";
const TWO_PI = 2 * Math.PI;
/**
* Wave functions
*/
const WAVE_SHAPES = {
sine: Math.cos,
triangle: (time) =>
(4 / TWO_PI) *
Math.abs(
((((time - TWO_PI / 4) % TWO_PI) + TWO_PI) % TWO_PI) - TWO_PI / 2
) -
1,
square: (time) => (time % TWO_PI < Math.PI ? 1 : -1),
saw: (time) => ((time % TWO_PI) - Math.PI) / Math.PI,
};
/**
* Relabi generator
*/
export default class Relabi {
/**
* Initialize generator
*/
constructor({ waves, bounds, parent }) {
this.updateTime = 1;
this.steps = 50;
this.waves = waves || [
{ shape: "triangle", frequency: randrange(0.5, 1.5) },
{ shape: "triangle", frequency: randrange(0.75, 2.25) },
{ shape: "triangle", frequency: randrange(1, 3) },
{ shape: "triangle", frequency: randrange(2, 4) },
];
this.bounds = bounds;
this.previousValue = null;
this.canvas = new RelabiCanvas({ relabi: this, parent });
}
/**
* Start the generator
*/
start() {
console.log("Start Relabi");
this.stop();
this.clock = new Tone.Clock((time) => {
const values = this.generate(time);
const notes = this.play(values);
this.canvas.append(time, values, notes);
}, this.updateTime);
this.clock.start();
}
/**
* Stop the generator and reset it
*/
stop() {
if (this.clock) {
this.clock.stop();
this.clock.dispose();
}
}
/**
* Generate relabi events
*/
generate(time) {
const waveCount = this.waves.length;
let index;
let step;
let value;
let values = [];
// Overshoot the line slightly each time
let stepCount = this.steps + 20;
// Generate several events per second
for (step = 0; step < stepCount; step += 1) {
// Time offset for this event
const timeOffset = time + (step * this.updateTime) / this.steps;
// Initialize value
value = 0;
// Compute the wave functions for this event
for (index = 0; index < waveCount; index += 1) {
const wave = this.waves[index];
value += WAVE_SHAPES[wave.shape](timeOffset * wave.frequency);
}
// Scale to [-1, 1]
value /= waveCount;
values.push([timeOffset, value]);
}
return values;
}
/**
* Schedule relabi events
*/
play(values) {
const boundsCount = this.bounds.length;
let previousValue = this.previousValue;
let index;
let step;
let noteCount = 0;
const notes = [];
for (step = 0; step < this.steps; step += 1) {
// Get the next value
const [time, value] = values[step];
// Compute whether we crossed a boundary, and which direction
for (index = 0; index < boundsCount; index += 1) {
const bound = this.bounds[index];
if (
value < bound.level &&
bound.level < previousValue &&
previousValue !== null
) {
// Going down
this.trigger(time, bound.sounds[0]);
notes.push([time, bound.level, true]);
noteCount += 1;
} else if (
value > bound.level &&
bound.level > previousValue &&
previousValue !== null
) {
// Going up
this.trigger(time, bound.sounds[1]);
notes.push([time, bound.level, false]);
noteCount += 1;
}
}
// Update the previous value
previousValue = value;
}
// Store the latest value
this.previousValue = previousValue;
// Return the notes
return notes;
}
/**
* Trigger an event
*/
trigger(time, sound) {
// console.log("trigger index", index, time);
sound.instrument.play(time, sound);
}
}
|
