class Attractor
{
  Particle p;
  private float r;
  private color c;
  
  Attractor(Particle _p, float _r, color _c)
  {
    p = _p;
    p.makeFixed();
    r = _r;
    c = _c;
  }
  
  void move(int d)
  {
    float s = 5;
    switch(d)
    {
      case 1: p.moveBy(0, -s, 0); break;
      case 2: p.moveBy(s, 0, 0); break;
      case 3: p.moveBy(0, s, 0); break;
      case 4: p.moveBy(-s, 0, 0); break;
    }
    if ( x() < r ) p.moveTo(r, y(), 0);
    else if ( x() > width - r ) p.moveTo(width - r, y(), 0);
    if ( y() < r ) p.moveTo(x(), r, 0);
    else if ( y() > height - r ) p.moveTo(x(), height - r, 0); 
  }
  
  void collide(Pebble peb)
  {
    float ad = dist(x(), y(), peb.x(), peb.y());
    float rd = r + peb.radius();
    if ( ad < rd )
    {
      float dx = (peb.x() - x())/ad;
      float dy = (peb.y() - y())/ad;
      peb.moveTo(x() + dx*rd, y() + dx*rd);
      peb.setVelocity(dx*20, dy*20);
    }
  }
  
  float radius()
  {
    return r;
  }
  
  float x()
  {
    return p.position().x();
  }
  
  float y()
  {
    return p.position().y();
  }
  
  void render()
  {
    fill(c);
    stroke(0);
    strokeWeight(2);
    ellipse(x(), y(), r, r);
  }
}