perlin noise

var particles_a = [];

var particles_b = [];

var particles_c = [];

var nums =200;

var noiseScale = 800;

​

function setup(){

  createCanvas(windowWidth, windowHeight);

  background(21, 8, 50);

  for(var i = 0; i < nums; i++){

    particles_a[i] = new Particle(random(0, width),random(0,height));

    particles_b[i] = new Particle(random(0, width),random(0,height));

    particles_c[i] = new Particle(random(0, width),random(0,height));

  }

}

​

function draw(){

  noStroke();

  smooth();

    for(var i = 0; i < nums; i++){

    var radius = map(i,0,nums,1,2);

    var alpha = map(i,0,nums,0,250);

​

    fill(69,33,124,alpha);

    particles_a[i].move();

    particles_a[i].display(radius);

    particles_a[i].checkEdge();

​

    fill(7,153,242,alpha);

    particles_b[i].move();

    particles_b[i].display(radius);

    particles_b[i].checkEdge();

​

    fill(255,255,255,alpha);

    particles_c[i].move();

    particles_c[i].display(radius);

    particles_c[i].checkEdge();

  }  

}

​

​

function Particle(x, y){

  this.dir = createVector(0, 0);

  this.vel = createVector(0, 0);

  this.pos = createVector(x, y);

  this.speed = 0.4;

​

  this.move = function(){

    var angle = noise(this.pos.x/noiseScale, this.pos.y/noiseScale)*TWO_PI*noiseScale;

    this.dir.x = cos(angle);

    this.dir.y = sin(angle);

    this.vel = this.dir.copy();

    this.vel.mult(this.speed);

    this.pos.add(this.vel);

  }

​

  this.checkEdge = function(){

    if(this.pos.x > width || this.pos.x < 0 || this.pos.y > height || this.pos.y < 0){

      this.pos.x = random(50, width);

      this.pos.y = random(50, height);

    }

  }

​

  this.display = function(r){

    ellipse(this.pos.x, this.pos.y, r, r);

  }

}