-
Notifications
You must be signed in to change notification settings - Fork 6
/
dft.js
91 lines (75 loc) · 1.54 KB
/
dft.js
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
/**
* DFT in webgl
*/
var regl = require('regl')();
module.exports = function (N, data) {
var text = regl.texture({
width: N,
height: 1,
format: 'alpha',
type: 'float',
data: data
});
return regl({
vert: `
precision highp float;
attribute vec2 position;
void main() {
gl_Position = vec4(position, 0, 1);
}
`,
frag: `
precision highp float;
uniform sampler2D waveform;
uniform vec2 viewport;
const float N = ${N}.;
const float rate = 44100.;
const float pi2 = ${Math.PI*2};
const float pi = ${Math.PI};
//phasor/source run state
float distance;
float step;
//accumulated resonance energy for a source
vec2 energy;
//base frequency of a phasor
float frequency;
//get energy state of a phasor
vec2 phasor () {
return vec2(
cos(pi2 * distance * frequency),
sin(pi2 * distance * frequency)
);
}
//get energy state of a source
vec2 source () {
return vec2(
texture2D(waveform, vec2(distance, 0)).w
);
}
void main () {
energy = vec2(0);
distance = 0.;
step = 1./N;
frequency = N * 0.5 * gl_FragCoord.x / viewport.x;
// sum all input values masked by frequency values
for (float i = 0.; i < N; i++) {
energy += dot(phasor(), source());
distance += step;
}
gl_FragColor = vec4(vec3(length(energy / N) * 255.), 1);
}
`,
attributes: {
position: regl.buffer(
[-1,-1, -1,3, 3,-1]
)
},
uniforms: {
waveform: text,
viewport: function (a,b,stats) {
return [stats.width,stats.height];
}
},
count: 3
});
};