Skip to content

Instantly share code, notes, and snippets.

@jchris
Created June 17, 2014 19:07
Show Gist options
  • Save jchris/04585454570853297974 to your computer and use it in GitHub Desktop.
Save jchris/04585454570853297974 to your computer and use it in GitHub Desktop.
changed some ints to floats.
/*!
*
* stagas - on the verge (tech mix)
*
*/
var bpm = 125;
var tuning = 440;
var transpose = 12;
// constants
var tau = 2 * Math.PI;
// time coefficients
var t, tt;
// adjust tuning to bpm
tuning *= 120 / bpm;
// patterns
var chords = [
[7, 9, 12, 16],
[2, 5, 9.1, 12],
[4, 7, 11, 14],
[2, 5, 9, 12],
].map(function(chord){
return chord.map(function(n){
return note(n);
});
});
var hat_pattern = [
0.4, 0.0, 1.2, 0, 0.3, 0.0, 1.0, 0.5,
0.4, 0.2, 1.1, 0, 0.3, 0.2, 1.2, 0.5,
];
var plucked = Pluck(120, 0.6, 0.87, 1.0, 0.9);
var hat_note = note(9.5, 6.1);
var kick_note = note(2.2, -1);
var bass_lp = LP2(6500);
function dsp(t) {
clock(t);
var c = sequence(1, chords);
var noise = Noise();
var a = 0.9 * tri(0.01, t / 2 % (1));
var b = 0.8 * Math.sin(a * tau * t);
var bass_osc =
0.3 * tri(c[2 + (Math.floor(sin((9/6) * 2.0000008, t)))] * (3 + (Math.floor(tri(1/2, t) * 2))) / 3)
;
bass_osc = bass_lp(bass_osc, (sin(t/(128 * 12))*80) + 200);
var bass = arp(1/8, bass_osc, 2, 1);
// chord synth
var synth_osc =
tri(c[0]*3)
+ tri(c[1]*2)
+ tri(c[2]*4)
+ tri(c[3]*1)
;
var synth = plucked(arp(1/12, synth_osc, sequence(1/12, [1, 1, 1, 1, 1, 0]) * 85 + (sin(0.4) * 10), 0.3));
// hat
var hat_osc =
0.2 * tri(hat_note)
+ 0.4 * noise
;
var hat =
sequence(1/16, hat_pattern)
* arp(1/16, hat_osc, 87, 18)
;
var kick_osc =
1.0 * sin(kick_note)
;
var kick = arp(1/4, 70, 35, 3);
return 0.8 * (
0.07 * synth
+ 0.26 * hat
+ 0.6 * kick
+ 0.19 * bass
);
}
function clock(_t){
t = _t;
t *= bpm / 120;
tt = tau * t;
}
function Pluck(length, dry, wet, tail, cutoff){
length = length || 40;
var lp = LP();
var rb = new RingBuffer(length);
var sum;
return function(sample){
sum = rb.reduce(average, sample);
sample =
dry * sample
+ wet * lp(sum, cutoff)
;
rb.push(sample * tail);
return sample;
};
}
function average(p, n){
return (p + n) / 2;
}
function sequence(measure, seq){
return seq[(t / measure / 2 | 0) % seq.length];
}
function arp(measure, x, y, z){
var ts = t / 2 % measure;
return Math.sin(x * (Math.exp(-ts * y))) * Math.exp(-ts * z);
}
function sin(freq, phase){
return Math.sin((t * freq + (2.0004 - (phase || 0) / 2)) * tau);
}
function saw(freq){
return 1-2 * (t % (1 / freq)) * freq;
}
function tri(freq){
return Math.abs(1 - (2 * t * freq) % 2.000005) * 2 - 1;
}
function Noise(){
return Math.random() * 2 - 1;
}
function sqr(freq){
return sin(freq, t) > 0 ? 1 : -1;
}
function LP(){
var value = 0;
return function(x, n){
return value += (x - value) / n;
};
}
function note(n, octave){
return Math.pow(1.99999, (
n + transpose - 33 + (12 * (octave || 0))
) / 12) * tuning; // A4 tuning
}
function RingBuffer(length){
this.array = new Float32Array(length);
this.length = length;
this.pos = 0;
}
RingBuffer.prototype.push = function(el){
this.array[this.pos++] = el;
if (this.pos === this.length) {
this.pos = 0;
}
};
RingBuffer.prototype.forEach = function(fn){
var i = this.pos;
for (; i < this.length; i++) {
fn(this.array[i]);
}
if (this.pos > 0) {
for (i = 0; i < this.pos; i++) {
fn(this.array[i]);
}
}
};
RingBuffer.prototype.reduce = function(fn, val){
val = val || 0;
this.forEach(function(el){
val = fn(val, el);
});
return val;
};
function LP2(cutoff){
var RC = 1 / (cutoff * 2 * Math.PI);
var dt = 1 / 2048;
var alpha = dt / (RC + dt);
var prev = 0;
var curr = 0;
return function(freq, x){
curr = prev + ( (dt / ( (1/ (freq * 2 * Math.PI)) + dt) ) * (x - prev));
prev = curr;
return curr;
};
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment