let scl;

let cols;

let rows;

​

let zoff;

​

let fr;

​

let particles = [];

​

let flowField = [];

​

function setup() {

  createCanvas(600, 600);

  zoff = 0;

  scl = 10;

  inc = 0.1;

  cols = floor(width / scl);

  rows = floor(height / scl);

  fr = createP();

​

  for (let i = 0; i < 2000; i++) {

    particles[i] = new Particle();

  }

  background(220);

}

​

function draw() {

  let yoff = 0;

  for (let y = 0; y < rows; y++) {

    let xoff = 0;

    for (let x = 0; x < cols; x++) {

      let index = (x + y * cols);

      let angle = noise(xoff, yoff, zoff) * TWO_PI;

      let v = p5.Vector.fromAngle(angle);

      v.setMag(1);

      flowField[index] = v;

      xoff += inc;

    }

    yoff += inc;

    zoff += 0.0002;

  }

​

  for (let i = 0; i < particles.length; i++) {

    particles[i].update();

    particles[i].edges();

    particles[i].show();    

    particles[i].follow(flowField);

  }

  fr.html(floor(frameRate()) + " fps");

}