class ParticleX
{
  public float x, y, direction, speed, gravity, gravity_direction, gravity_current;
  private float a;
  public boolean alive;
  public ParticleX()
  {
    alive = true;
    a = 255;
    x = 0;
    y = 0;
    direction = 0;
    speed = 0;
    gravity = 0;
    gravity_current = 0;
    gravity_direction = 0;
  }
  public void step()
  {
    if(speed > 0 || speed < 0)
    {
      float[] c = move_in_direction(x, y, direction, speed);
      x = c[0];
      y = c[1];
    }
    // Apply gravity
    if(gravity > 0 || gravity < 0)
    {
      gravity_current += gravity;
      float[] c = move_in_direction(x, y, gravity_direction, gravity_current);
      x = c[0];
      y = c[1];
    }
    // Do user-defined stuff
    customstep();
  }
  private void customstep()
  {
    
  }
  public void draw(float R, float G, float B)
  {
    stroke(R,G,B, a);
    fill(R,G,B,a);
    a -= 3;
    if(a < 0) alive = false;
    ellipse(x, y, 5, 5);
  }
}