class Particle {
  private PVector pos;
  private PVector v;
  
  public Particle( PVector pos ) {
    this.pos = pos;
    this.v = new PVector( 0,0,0 );
  }
  
  public Particle( PVector pos, PVector v ) {
    this.pos = pos;
    this.v = v;
  }
 
  void update() {
    if ( pos.y < 58 ) {
      pos.add(v);
      v.y += 1;
    } else {
      v.mult( 0.3 );
      v.y = -v.y;
      pos.add(v);
    }
  }
  
  void draw() {
    pushMatrix();
    translate( pos.x, pos.y, pos.z );
    box(2);
    popMatrix();
  }
}