let paused = false;

let seed = 1;

let colors;

​

function keyPressed() {

  if (key === " ") paused = !paused;

}

​

class Particle {

  constructor() {

    this.radius = random(0.5, 2);

    this.diameter = this.radius * 2;

    this.velocity = createVector(10, 10); //random(-2,2), random(-2,2));

    this.alpha = 100;

​

    this.position = createVector(

      random(this.radius, width - this.radius),

      random(this.radius, height - this.radius)

    );

​

    let _r = random();

    if (_r > 0.66) 

      this.color = colors[2];

      // this.color = color(255, 0, 0, this.alpha);

    else if (_r > 0.33) 

      this.color = colors[3];

      // this.color = color(0, 0, 255, this.alpha);

    else 

      this.color = colors[4];

      // this.color = color(0, 255, 0, this.alpha);

    this.color._array[3] = this.alpha/255;

  }

​

  update() {

    this.position.x += this.velocity.x;

    this.position.y += this.velocity.y;

​

    let change = false;

    if (

      this.position.x < this.radius ||

      this.position.x > width - this.radius

    ) {

      this.velocity.x *= -1;

      change = true;

    }

    if (

      this.position.y < this.radius ||

      this.position.y > height - this.radius

    ) {

      this.velocity.y *= -1;

      change = true;

    }

​

    if (random() > 0.99) {

      this.alpha = constrain(this.alpha, 0, 25 );

      if (random() > 0.5) {

      this.velocity.x = random(-2, 2);

      this.velocity.y = 0;

      } else {

        this.velocity.x = 0;

      this.velocity.y = random(-2, 2);

      }

      this.alpha -= 1;//0.5;

      this.color = colors[1];//color(255,255,255,this.alpha);

      this.color._array[3] = this.alpha/255;

    }

​

    if (change) {

      this.alpha -= 5;

    }

    if (this.alpha <= 0) {

      this.alpha = 0;

      this.dead = true;

    }

    this.color._array[3] = this.alpha / 255;

  }

  draw() {

    noStroke();

    fill(this.color);

    circle(this.position.x, this.position.y, this.diameter);

  }

}

​

function setup() {

  randomSeed(seed);

  // https://www.colourlovers.com/palette/4834108/All_bark_no_bite

  // colors = [

  //   color("#9CB2A0"),

  //   color("#A27C70"),

  //   color("#815E53"),

  //   color("#DB703E"),

  //   color("#CFAD94")

  // ];

  colors = [

    color(0,0,0),

    color(255,0,0),

    color(0,255,0),

    color(0,0,255),

    color(255,0,255)

  ]

  particles = [];

  let numParticles = 1250; //50;

​

  // createCanvas(600, 600);

  createCanvas(7200,7200);

  // createCanvas(3840, 2160);

​

  for (let i = 0; i < numParticles; i++) {

    particles.push(new Particle());

  }

​

  // background(0);

  background(colors[0]);

}

​

function draw() {

  if (!paused) {

    // background(0);

​

    for (let i = particles.length - 1; i >= 0; i--) {

      let p = particles[i];

      p.update();

      p.draw();

​

      if (p.dead) particles.splice(i, 1);

    }

​

    if (particles.length == 0) {

      console.log("done");

      noLoop();

    }

  }

}

​