// TB303-like synth.
// 2022/12/4, srtuss
// patterns are encoded as 4 values per step: note,rest,slide,accent (rests are not implemented)
var patterns = [
[f3,1,1,0,f2,1,0,0,ds2,1,1,0,c2,1,0,0,f2,1,1,0,f3,1,1,0,f3,1,0,0,f3,1,0,0,f2,1,0,0,f3,1,1,0,c2,1,0,0,ds3,1,0,0,f3,1,1,0,c3,1,0,0,ds3,1,0,0,f3,1,0,0],
[a3,1,1,1,a3,1,0,0,a3,1,0,0,a3,1,1,0,a2,1,0,0,a4,1,0,0,a3,1,1,0,a2,1,0,0,a3,1,0,1,a3,1,1,0,a2,1,0,0,c4,1,1,0,a2,1,0,0,c3,1,0,0,a2,1,0,0,a3,1,0,0],
[c2,1,1,0,c3,1,0,0,c4,1,0,0,c3,1,0,0,c2,1,0,0,c4,1,1,0,c3,1,1,0,c3,1,0,0],
[c3,1,1,1,c3,1,0,0,c4,1,0,0,c3,1,1,1,c4,1,0,0,c3,1,0,0,c4,1,1,0,c3,1,0,0]
];
const pblep = (t, dt) => {
if(t < dt) {
t /= dt;
return t + t - t * t - 1;
}
else if (t > 1 - dt) {
t = (t - 1) / dt;
return t * t + t + t + 1;
}
return 0;
}
input.gate=.58; // min=.1,max=1,step=.02
input.tune=-18; // min=-24,max=24,step=.01
input.waveform=0;
input.cutoff=0.28;
input.resonance=0.6;
input.envmod=0;
input.decay=0;
input.overdrive=0;
input.pattern = 1; // min=0, max=3, step=1 (bad square, synthetic b*tch, chainsaw, flying)
input.echo = .8; // value=.8
ditty.bpm = 138;
class SVFilter {
constructor() {
this.lastLp = 0;
this.lastHp = 0;
this.lastBp = 0;
this.kf = 0.1;
this.kq = .1;
}
process(input) {
var lp = this.lastLp + this.kf * this.lastBp;
var hp = input - lp - this.kq * this.lastBp;
var bp = this.lastBp + this.kf * hp;
this.lastLp = lp;
this.lastHp = hp;
this.lastBp = bp;
return lp;
}
}
class SVFilter2 {
constructor() {
this.f = [new SVFilter(), new SVFilter()];
this.lastLp = 0;
this.kf = 0.1;
this.kq = .3;
}
process(input) {
this.f[0].kf = this.kf;
this.f[0].kq = this.kq;
this.f[1].kf = this.kf;
this.f[1].kq = this.kq;
this.f[0].process(input);
this.f[1].process(this.f[0].lastLp);
this.lastLp = this.f[1].lastLp;
return this.lastLp;
}
}
class Convol {
constructor() {
this.kernel = [0.013475, 0.097598, 0.235621, 0.306612, 0.235621, 0.097598, 0.013475];
this.taps = new Float32Array(this.kernel.length);
}
process(v) {
var n = this.kernel.length;
var t = this.taps;
for(var i = n-1; i > 0; --i)
t[i] = t[i-1];
t[0] = v;
var o = 0;
for(var i = 0; i < n; ++i)
o += this.kernel[i] * t[i];
return o;
}
}
class TbVoice {
constructor(opt) {
this.ph = 0;
this.dtph = .001;
this.flt = new SVFilter2();
this.tclk = 0;
this.dtclk = ditty.bpm / 60 * 4 * ditty.dt;
this.clkidx = 0;
this.sqidx = 0;
this.lastgate = 0;
this.venv = 0;
this.fenv = 0;
this.slide = 0;
this.note = 0;
this.notecap = 0;
this.att = 0;
this.accent = 0;
this.aenv = 0;
this.us = new Convol();
this.ds = new Convol();
}
seqstep() {
var patdata = patterns[input.pattern];
var pl = patdata.length>>2;
this.sqidx %= pl;
this.slide = patdata[this.sqidx*4+2];
this.xslide = patdata[((this.sqidx+pl-1)%pl)*4+2];
this.note = patdata[this.sqidx*4] + input.tune;
this.accent = patdata[this.sqidx*4+3];
this.sqidx++;
this.sqidx %= pl;
}
process(note, env, tick, opt) {
while(this.tclk >= 1) {
this.tclk -= 1;
this.seqstep();
}
var gate = this.tclk < input.gate || this.slide;
this.tclk += this.dtclk;
if(gate) {
if(!this.lastgate) {
this.fenv = 1;
this.att = 0;
this.aenv = this.accent;
}
this.venv = 1;
this.att = Math.min(this.att+ditty.dt/.0005, 1);
}
this.lastgate = gate;
if(this.xslide) {
this.notecap += (this.note - this.notecap) * .0005;
}
else {
this.notecap = this.note;
}
this.dtph = midi_to_hz(this.notecap) * ditty.dt;
this.venv *= .995;
this.fenv *= Math.exp(-(1-input.decay) * .004);
var blep0 = pblep(this.ph, this.dtph);
var saw = this.ph * 2 - 1 - blep0;
var pw = Math.max(.5, input.waveform)*.95;
var square = (this.ph > pw ? 1 : -1) + pblep((this.ph-pw+1)%1, this.dtph) - blep0;
var v = lerp(saw, square, clamp01(input.waveform * 2));
this.flt.kq = 1 - input.resonance * .9 - this.aenv * .1;
this.flt.kf = 2 ** Math.min(0, input.cutoff * 7 - 7 + this.fenv * input.envmod * 5 + this.aenv * .4);
this.flt.process(v);
v = this.flt.process(v);
this.ph += this.dtph;
while(this.ph >= 1) {
this.ph -= 1;
}
v = v * this.venv * this.att * (this.aenv + 1);
this.aenv *= .9995;
v *= .5;
if(input.overdrive > 0) {
var e = [0, 0, 0, 0];
e[0] = this.us.process(v*4);
e[1] = this.us.process(0);
e[2] = this.us.process(0);
e[3] = this.us.process(0);
for(var i = 0; i < 4; ++i) {
e[i] = clamp(e[i] * (1+input.overdrive*8), -1, 1);
}
this.ds.process(e[0]);
this.ds.process(e[1]);
this.ds.process(e[2]);
v = this.ds.process(e[3]);
}
return v;
}
}
class Delayline {
constructor(n) {
this.n = ~~n;
this.p = 0;
this.lastOutput = 0;
this.data = new Float32Array(n);
}
clock(input) {
this.lastOutput = this.data[this.p];
this.data[this.p] = input;
if(++this.p >= this.n) {
this.p = 0;
}
}
tap(offset) {
var x = this.p - offset - 1;
x %= this.n;
if(x < 0) {
x += this.n;
}
return this.data[x];
}
}
const stereoEcho = filter.def(class {
constructor(options) {
this.lastOutput = [0, 0];
var time = 60 / ditty.bpm;
//time *= 3 / 4;
time /= 2;
var n = Math.floor(time / ditty.dt);
this.delay = [new Delayline(n), new Delayline(n)];
this.dside = new Delayline(500);
this.kfbl = .4;
this.kfbr = .7;
}
process(inv, options) {
this.dside.clock(inv[0]);
var new0 = (this.dside.lastOutput + this.delay[1].lastOutput) * this.kfbl;
var new1 = (inv[1] + this.delay[0].lastOutput) * this.kfbr;
this.lastOutput[0] = inv[0] + this.delay[0].lastOutput * input.echo;
this.lastOutput[1] = inv[1] + this.delay[1].lastOutput * input.echo;
this.delay[0].clock(new0);
this.delay[1].clock(new1);
return this.lastOutput;
}
});
const tbvoice = synth.def(TbVoice);
loop( () => {
tbvoice.play(c0, {duration:600, release:.1, amp: .25});
sleep(600);
}, { name: 'acid' }).connect(stereoEcho.create());
