고전 Snake 게임 만들기

이 문서는 원래 mariokandut.com에 게시되었습니다.

이것은 자습서Create the classic Snake game - React의 두 번째 부분입니다. 첫 번째 부분은 에서 찾을 수 있습니다.

튜토리얼의 첫 번째 부분을 따랐다면 다음이 있어야 합니다.

움직이는 제어 가능한 뱀

경계 충돌 감지

임의로 생성된 사과

사과 충돌 감지(사과를 먹는 뱀)

사과를 먹으면 뱀이 자란다

누락된 부품과 기능을 계속 살펴보겠습니다.

목차 - 파트 2

Fix collision detection for opposite direction keys

Styling Updates and Autofocus

Game Points

Game End

1. 반대 방향 키에 대한 충돌 감지 수정

Currently, the collision detection return true if we press the opposite key of the current direction the snake is moving. For example: The key ArrowRight is pressed, so the snake moves right, and then the key ArrowLeft is pressed. This would trigger a collision, which is a wrong behaviour. We have to fix this.

An easy way to fix this, is to filter out keys which are in the opposite direction. Since we have a state for direction and coordinates for arrow keys, we can simply sum up the current direction and the arrow direction.

The sum of x-coordinates for ArrowLeft and ArrowRight equal 0 and return a falsy value, hence this can be filtered.

  ArrowLeft: { x: -1, y: 0 },
  ArrowRight: { x: 1, y: 0 },

Update the moveSnake with the following code:

const moveSnake = (event: React.KeyboardEvent) => {
  const { key } = event;
  // Check if key is arrow key
  if (
    key === 'ArrowUp' ||
    key === 'ArrowDown' ||
    key === 'ArrowRight' ||
    key === 'ArrowLeft'
  ) {
    // disable backwards key, this means no collision when going right, and then pressing ArrowLeft
    if (
      direction.x + directions[key].x &&
      direction.y + directions[key].y
    ) {
      setDirection(directions[key]);
    }
  }
};

2. 스타일링 업데이트 및 자동 초점

The styling of the game needs some improvement, and we have to add an overlay, if we lost the game, and autofocus. The styling will be made in the App.css , there are plenty of other ways to do styling in a React application. What styling method do you prefer? Leave a comment.

The game wrapper should be autofocussed, after the start button is clicked. We have access to the focus() method, when we use the useRef hook.

Add the wrapperRef and a state for isPlaying:

// add wrapper ref and isPlaying flag for showing start button
const wrapperRef = useRef<HTMLDivElement>(null);
const [isPlaying, setIsPlaying] = useState<boolean>(false);

Now we have to update the startGame and endGame function:

// update startGame
const startGame = () => {
    setIsPlaying(true);
    setSnake(SNAKE_START);
    setApple(APPLE_START);
    setDirection(DIRECTION_START);
    setSpeed(SPEED);
    setGameOver(false);
    wrapperRef.current?.focus();
  };

// update endGame
const endGame = () => {
    setIsPlaying(false);
    setSpeed(null);
    setGameOver(true);
  };

Now we update the wrapper with some classNames and some condition for an overlay and the reference.

// Update div with classes and flag for showing buttons, conditional styles
return (
  <div className="wrapper">
    <div
      ref={wrapperRef}
      className="canvas"
      role="button"
      tabIndex={0}
      onKeyDown={(event: React.KeyboardEvent) => moveSnake(event)}
    >
      <canvas
        style={
          gameOver
            ? { border: '1px solid black', opacity: 0.5 }
            : { border: '1px solid black' }
        }
        ref={canvasRef}
        width={CANVAS_SIZE.x}
        height={CANVAS_SIZE.y}
      />
      {gameOver && <div className="game-over">Game Over</div>}
      {!isPlaying && (
        <button className="start" onClick={startGame}>
          Start Game
        </button>
      )}
    </div>
  </div>
);

Now we can update our styling.

.wrapper {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  height: 100vh;
}
.canvas {
  display: flex;
  justify-content: center;
  align-items: center;
  background: rgb(151, 216, 148);
  position: relative;
}

.start {
  font-size: 1rem;
  position: absolute;
  border: 1px solid black;
  background: none;
  border-radius: 1rem;
  padding: 1rem;
  outline: none;
}

.start:hover {
  border: none;
  background: white;
}

.game-over {
  position: absolute;
  font-size: 5rem;
  margin-bottom: 10rem;
}

The fillStyle should be updated as well from red and green to #1C1B17 , so we have this retro feeling/styling of the game.

We have now a working and styled version of the Classic Snake Game. Well, done. 😎

What's next?

Adding points
Game End

3. 게임 포인트

Add state for points:

const [points, setPoints] = useState<number>(0);

Add setPoints to startGame to reset score:

setPoints(0);

Increase points if apple is eaten, add this to checkAppleCollision :

setPoints(points + 1);

Add points to game wrapper:

<p className="points">{points}</p>

Add some styling for the points:

.points {
  position: absolute;
  bottom: 0;
  right: 1rem;
  font-size: 2rem;
}

4. 게임 종료

We have to define a condition, when somebody has finished the game, which is unlikely, though to be feature-complete. The game end, besides a collision, would be the reaching of the maximum of available points. With the current scaling, the calculation is 40x40 = 1600points.

So we just add a condition to check if the maxPoints are reached and update the state and show some message.

We add the state to track if the game hasFinished

const [hasFinishedGame, setHasFinishedGame] = useState<boolean>(
  false,
);

We add some condition to show the hasFinished message.

{
  hasFinishedGame && <p className="finished-game">Congratulations</p>;
}

.finished-game {
  position: absolute;
  top: 60px;
  font-size: 5rem;
  color: red;
  text-decoration: underline;
}

We add a variable for maxPoints and import it into App.tsx :

export const maxPoints = 1600;

We add the check if maxPoints have been reached:

const checkAppleCollision = (newSnake: ICoords[]) => {
  if (newSnake[0].x === apple.x && newSnake[0].y === apple.y) {
    let newApple = createRandomApple();
    while (checkCollision(newApple, newSnake)) {
      newApple = createRandomApple();
    }
    setPoints(points + 1);
    if (points === maxPoints) {
      setHasFinishedGame(true);
      endGame();
    }
    setApple(newApple);
    return true;
  }
  return false;
};

In case hasFinishedGame has been set to true and we start a new game, the value has to be resetted.

const startGame = () => {
    setHasFinishedGame(false);
    setPoints(0);
    setIsPlaying(true);
    setSnake(snake_start);
    setApple(apple_start);
    setDirection(direction_start);
    setSpeed(initial_speed);
    setGameOver(false);
    wrapperRef.current?.focus();
  };

That's it. We can always come back and add more features, like sound effects or saving the score in localStorage or ...

Yay, ✨✨ Congratulations ✨✨. Well, done.

Your Game should look like this.

읽어 주셔서 감사합니다. 궁금한 점이 있으면 댓글 기능을 사용하거나 메시지를 보내주세요.

참조(및 큰 감사): Maksim 및 .

Reference

이 문제에 관하여(고전 Snake 게임 만들기 - React II), 우리는 이곳에서 더 많은 자료를 발견하고 링크를 클릭하여 보았다 https://dev.to/mariokandut/create-the-classic-snake-game-react-ii-3o8h

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