/**
   * Render the game (part of the main loop, no allocations anywhere in here).
   *
   * @param gl openGL context reference
   */
  public void render(GL10 gl) {

    GLGfx.clearScreen(gl, true, CLEAR_COLOR, true);

    mBack.draw(gl);

    GLGfx.drawLine(
        gl, RAIL_COLOR, 0, BANNER_HEIGHT * mDensity, getWidth(), BANNER_HEIGHT * mDensity);

    mPaddles[0].draw(gl);
    mPaddles[1].draw(gl);
    mBall.draw(gl);
  }