// #13 Advanced Envelopes. DittyToy 2022.
// The MIT License.
//
// https://dittytoy.net/ditty/d0b9a59b10
//
// Create and use an envelope manually. You can create an envelope object using the create method on the envelope definition.
//
// Note that you have to sample the value property every frame to make sure the envelope is correctly updated.
//
// adsr      envelope: https://dittytoy.net/ditty/34e1600f63
// adsr2     envelope: https://dittytoy.net/ditty/0f2e4c2cdd
// segmented envelope: https://dittytoy.net/ditty/ce63852ccf
//
// https://dittytoy.net/syntax#envelopes
//

const osc = synth.def( 
    class {
            constructor(options) {
                this.phase = 0;
                this.hist0 = 0;
                this.hist1 = 0;
                
                // Create an adsr envelope for the low pass filter
                // Attack, decay and release in seconds. Duration in ticks. 
                this.lowPassEnv = adsr.create({attack: 0.05, decay: 0.15, sustain: .25, release: 0.1, duration: options.duration});
            }
            process(note, env, tick, options) {
                this.phase += midi_to_hz(note) * ditty.dt;
                
                let ret = this.phase % 1 - .5;

                // low pass filter, cutoff is based on lowPass envelope
                const alpha = clamp01(this.lowPassEnv.value * .5 ** 2);
                this.hist0 += alpha * (ret - this.hist0);
                this.hist1 += alpha * (this.hist0 - this.hist1);
                
                return this.hist1;
            }
    }, { attack: 0.01, release: 0.1, duration: 0.25 } );


loop( () => {
    for (let i=0; i<4; i++) {
        osc.play(c4, { attack: 0.01, release: 0.25,  duration: 0.125, amp: 1.0 });
        sleep( 0.25 );
    }

    osc.play(d4, { attack: 0.01, release: 0.25,  duration: 0.25 }); // attack and release in seconds, duration in ticks
    sleep(0.5); // sleep in ticks

    osc.play(f4, { attack: 0.01, release: 0.75,  duration: 0.25 });
    sleep(0.5);
}, { name: 'Advanced Envelopes' });