class Particle {
  Vector3D loc;
  Vector3D vel;
  Vector3D acc;
  float r; // size
  float timer; //timespan

  Particle(Vector3D loc_, Vector3D vel_, Vector3D acc_, float r_) {
    loc = loc_.copy();
    vel = vel_.copy();
    acc = acc_.copy();
    r = r_;
    timer = 50.0;
  }

  void run() {
    update();
    timer();
    render();
  }

  // particle update location method
  void update() {
    vel.add(acc);
    loc.add(vel);
  }

  void timer() {
    timer -= 1.0;
  }

  void render() {
    ellipseMode(CENTER);
    noStroke();
    fill(255,timer*2);
    ellipse(loc.x, loc.y, r,r);
  }



  boolean dead() {
    if(timer <= 0.0) {
      return true;
    } 
    else { 
      return false;
    }
  }
}