// Daniel Shiffman

// http://natureofcode.com

​

// Simple Particle System

​

class Particle {

​

  constructor(x, y, r) {

    this.position = createVector(x, y);

    this.acceleration = createVector();

    this.velocity = createVector()

    this.lifespan = 255.0;

    this.r = r;

  }

​

  run() {

    this.update();

    this.display();

  }

​

  applyForce(force) {

    this.acceleration.add(force);

  }

​

  // Method to update position

  update() {

    this.velocity.add(this.acceleration);

    this.position.add(this.velocity);

    this.acceleration.mult(0);

    this.velocity.mult(0.97);

    this.lifespan -= 2.0;

  }

​

  // Method to display

  display() {

    stroke(255);

    fill(255);

    rectMode(CENTER);

    rect(this.position.x, this.position.y, this.r, this.r);

  }

​

  // Is the particle still useful?

  isDead() {

    if (this.lifespan < 0.0) {

      return true;

    } else {

      return false;

    }

  }

}