constructor(n, r, ix=0, iy=0) {

    this.xs = [[ix, iy]];

    while(this.xs.length < n) {

      this.xs.push([ix,iy]);

    }

    this.r = r;

  }

  move(x,y) {

    this.xs[0][0] = x;

    this.xs[0][1] = y;

    for(let i = 0; i < this.xs.length - 1; i++) {

      const dx = this.xs[i][0] - this.xs[i+1][0];

      const dy = this.xs[i][1] - this.xs[i+1][1];

      const d2 = dx*dx + dy*dy;

      if(d2 > this.r * this.r) {

        const a = Math.atan2(dy, dx);

        this.xs[i+1][0] = -Math.cos(a) * this.r + this.xs[i][0];

        this.xs[i+1][1] = -Math.sin(a) * this.r + this.xs[i][1];

      }

    }

  }

  render() {

    stroke(255);

    let first = true;

    let ix, iy;

    for(const [x,y] of this.xs) {

      if(first) {

        ix = x;

        iy = y;

        first = false;

      } else {

        line(ix, iy, x, y);

        ix = x;

        iy = y;

      }

    }

  }

}

const s = new DotString(100, 3)

function setup() {

  createCanvas(600, 600);

}

​

let tx, ty, t, cx = 0, cy = 0;

function randTarget() {

  tx = Math.random() * 600;

  ty = Math.random() * 600;

  t = Math.floor(Math.random() * 12 + 6);

}

randTarget();

function draw() {

  background(0);

  if(t == 0) randTarget();

  else t--;

  cx += (tx - cx)/25;

  cy += (ty - cy)/25;

  s.move(cx, cy);

  s.render();

}

​