// A subclass of Particle
  
  class CrazyParticle extends Particle {
  
    // Just adding one new variable to a CrazyParticle
    // It inherits all other fields from "Particle", and we don't have to retype them!
    float theta;
  
    // The CrazyParticle constructor can call the parent class (super class) constructor
    CrazyParticle(PVector l) {
      // "super" means do everything from the constructor in Particle
      super(l);
      // One more line of code to deal with the new variable, theta
      theta = 0.0;
  
    }
  
    // Notice we don't have the method run() here; it is inherited from Particle
  
    // This update() method overrides the parent class update() method
    void update() {
      super.update();
      // Increment rotation based on horizontal velocity
      float theta_vel = (vel.x * vel.mag()) / 10.0f;
      theta += theta_vel;
    }
  
    // Override timer
    void timer() {
      timer -= 0.5;
    }
    
    // Method to display
    void render() {
      // Render the ellipse just like in a regular particle
      super.render();
  
      // Then add a rotating line
      pushMatrix();
      translate(loc.x,loc.y);
      rotate(theta);
      stroke(255,timer);
      line(0,0,25,0);
      popMatrix();
    }
  }