class Particle
{
  public float x = 0;
  public float y = 0;
  public float vx = 0;
  public float vy = 0;
  public float k = .008;
  public boolean lines = false;
  private float rnd = .75;
  private float grav = .02;
  
  public void Particle()
  {
  }
  
  public void move()
  {
    float dx = mouseX - x;
    float dy = mouseY - y;
    float distSQ = dx*dx + dy*dy;
    float dist = sqrt(distSQ);
    float force = 500 / distSQ;
    vx += force * dx / dist;
    vy += force * dy / dist;
//    vx += random(-rnd, rnd);
//    vy += random(-rnd, rnd);
    vy += grav;
    vx *= .9;
    vy *= .9;
    vx = min(vx, 20);
    vx = max(vx, -20);
    vy = min(vy, 20);
    vy = max(vy, -20);
    x += vx;
    y += vy;
    if(x > w)
    {
      x = w;
      vx *= -1;
    }
    if(x<0)
    {
      x = 0;
      vx *= -1;
    }
    if(y > h)
    {
      y = h;
      vy *= -1;
    }
    if(y < 0)
    {
      y = 0;
      vy *= -1;
    }
  }
  
  public void render()
  {
    stroke(255, 128);
    if(lines)
    {
      line(x, y, x-vx, y-vy);
    }
    else
    {
      point(x, y);
    }
  }
}