private void drawGameOverUI() {
    Graphics g = game.getGraphics();

    g.drawPixmap(Assets.gameOver, 62, 100);
    g.drawPixmap(Assets.buttons, 128, 200, 0, 128, 64, 64);
    g.drawLine(0, 416, 480, 416, Color.BLACK);
  }
  private void drawWorld(World world) {
    Graphics g = game.getGraphics();
    Snake snake = world.snake;
    SnakePart head = snake.parts.get(0);
    Stain stain = world.stain;

    Pixmap stainPixmap = null;
    if (stain.type == Stain.TYPE_1) stainPixmap = Assets.stain1;
    if (stain.type == Stain.TYPE_2) stainPixmap = Assets.stain2;
    if (stain.type == Stain.TYPE_3) stainPixmap = Assets.stain3;
    int x = stain.x * 32;
    int y = stain.y * 32;
    g.drawPixmap(stainPixmap, x, y);

    int len = snake.parts.size();
    for (int i = 1; i < len; i++) {
      SnakePart part = snake.parts.get(i);
      x = part.x * 32;
      y = part.y * 32;
      g.drawPixmap(Assets.tail, x, y);
    }

    Pixmap headPixmap = null;
    if (snake.direction == Snake.UP) headPixmap = Assets.headUp;
    if (snake.direction == Snake.LEFT) headPixmap = Assets.headLeft;
    if (snake.direction == Snake.DOWN) headPixmap = Assets.headDown;
    if (snake.direction == Snake.RIGHT) headPixmap = Assets.headRight;
    x = head.x * 32 + 16;
    y = head.y * 32 + 16;
    g.drawPixmap(headPixmap, x - headPixmap.getWidth() / 2, y - headPixmap.getHeight() / 2);
  }
  private void drawRunningUI() {
    Graphics g = game.getGraphics();

    g.drawPixmap(Assets.buttons, 0, 0, 64, 128, 64, 64);
    g.drawLine(0, 416, 480, 416, Color.BLACK);
    g.drawPixmap(Assets.buttons, 0, 416, 64, 64, 64, 64);
    g.drawPixmap(Assets.buttons, 256, 416, 0, 64, 64, 64);
  }
  @Override
  public void present(float deltaTime) {
    Graphics g = game.getGraphics();

    g.drawPixmap(Assets.background, 0, 0);
    drawWorld(world);
    if (state == GameState.Ready) drawReadyUI();
    if (state == GameState.Running) drawRunningUI();
    if (state == GameState.Paused) drawPausedUI();
    if (state == GameState.GameOver) drawGameOverUI();

    drawText(g, score, g.getWidth() / 2 - score.length() * 20 / 2, g.getHeight() - 42);
  }
  public void drawText(Graphics g, String line, int x, int y) {
    int len = line.length();
    for (int i = 0; i < len; i++) {
      char character = line.charAt(i);

      if (character == ' ') {
        x += 20;
        continue;
      }

      int srcX = 0;
      int srcWidth = 0;
      if (character == '.') {
        srcX = 200;
        srcWidth = 10;
      } else {
        srcX = (character - '0') * 20;
        srcWidth = 20;
      }

      g.drawPixmap(Assets.numbers, x, y, srcX, 0, srcWidth, 32);
      x += srcWidth;
    }
  }
  private void drawPausedUI() {
    Graphics g = game.getGraphics();

    g.drawPixmap(Assets.pause, 80, 100);
    g.drawLine(0, 416, 480, 416, Color.BLACK);
  }
  private void drawReadyUI() {
    Graphics g = game.getGraphics();

    g.drawPixmap(Assets.ready, 47, 100);
    g.drawLine(0, 416, 480, 416, Color.BLACK);
  }