input.baseFrequency = 40; // min=20, max=100, step=1
input.loopEveryNTicks = 180; // min=20, max=300, step=1
input.shepardType = 2; // min=0, max=2, step=1 (Up, Down, Both)

const octaves = 6;

for(let i = 0; i < octaves; i++) {
    const getFp = (t) => (octaves * (t % input.loopEveryNTicks)) / input.loopEveryNTicks;
    
    synth.def( class {
        constructor (options) {
            this.phaseUp = 0;
            this.phaseDown = 0;
        }
        
        process(note, env, tick, options) {
            let fp = (getFp(tick) + i) % octaves;
            
            let frequencyUp = input.baseFrequency * 2**fp;
            let frequencyDown = input.baseFrequency * 2**(octaves - fp);
            this.phaseUp += ditty.dt * frequencyUp;
            this.phaseDown += ditty.dt * frequencyDown;
            const waveUp = Math.sin( this.phaseUp * Math.PI * 2 );
            const waveDown = Math.sin( this.phaseDown * Math.PI * 2 );
            
            switch(input.shepardType) {
                case 0:
                    return [waveUp, waveUp];
                case 1: 
                    return [waveDown, waveDown];
            }
            return [waveUp, waveDown];
        }
    }).play(0, { env: one, amp: 
        () => Math.sin(
            getFp(ditty.tick + (i * (input.loopEveryNTicks / octaves)))/octaves * Math.PI
        )**6
    })
};