let spacing = 15;

​

let start = [];

let vel = [];

​

let angle = 0;

​

​

function setup() {

  createCanvas(400, 400);

  angleMode(DEGREES);

  for (let i=0; i<count; i++){

    start[i] = 0; 

    vel[i] =(i+1) * 0.5;

  }

}

​

function draw() {

  background(20);

  translate(width/2, height/2);

  noFill();

  strokeWeight(4);

  for (let i=0; i<count; i++){

    stroke(200, 120*(i/count), 0);

    // stroke(120*(i/count), 120, 120);

    start[i] = constrain(start[i], 0, 180); 

    arc(0, 0, (i+1)*spacing, (i+1)*spacing, angle + (-180), angle + (-180 + start[i]));

    arc(0, 0, (i+1)*spacing, (i+1)*spacing, angle + 0, angle + start[i]);

    if (start[i] <= 0){

      vel[i] = vel[i] * -1;

    } else if (start[i] >= 180) {

      vel[i] = vel[i] * -1;

    }

    start[i] = start[i] + vel[i];

    angle = angle + 0.1;

​

  }

​

}

​