// 游戏常量const GRID_SIZE = 20;const CELL_SIZE = 20;const GAME_SPEED = 100; // 毫秒
// 游戏状态let snake = [];let food = {};let direction = 'right';let nextDirection = 'right';let score = 0;let gameInterval;let isGameRunning = false;
// DOM元素const canvas = document.getElementById('gameCanvas');const ctx = canvas.getContext('2d');const scoreElement = document.getElementById('score');const startBtn = document.getElementById('startBtn');
// 初始化游戏function initGame() { // 初始化蛇 snake = [ {x: 10, y: 10}, {x: 9, y: 10}, {x: 8, y: 10} ];
// 初始化食物 generateFood();
// 重置方向和分数 direction = 'right'; nextDirection = 'right'; score = 0; scoreElement.textContent = score;}
// 生成食物function generateFood() { food = { x: Math.floor(Math.random() * GRID_SIZE), y: Math.floor(Math.random() * GRID_SIZE) };
// 确保食物不会生成在蛇身上 for (let segment of snake) { if (segment.x === food.x && segment.y === food.y) { return generateFood(); } }}
// 游戏循环function gameLoop() { update(); draw();}
// 更新游戏状态function update() { // 更新蛇的方向 direction = nextDirection;
// 计算蛇头新位置 const head = {...snake[0]}; switch (direction) { case 'up': head.y--; break; case 'down': head.y++; break; case 'left': head.x--; break; case 'right': head.x++; break; }
// 检查碰撞 if ( head.x < 0 || head.x >= GRID_SIZE || head.y < 0 || head.y >= GRID_SIZE || snake.some(segment => segment.x === head.x && segment.y === head.y) ) { gameOver(); return; }
// 添加新头部 snake.unshift(head);
// 检查是否吃到食物 if (head.x === food.x && head.y === food.y) { score++; scoreElement.textContent = score; generateFood(); } else { // 如果没有吃到食物，移除尾部 snake.pop(); }}
// 绘制游戏function draw() { // 清空画布 ctx.fillStyle = '#ecf0f1'; ctx.fillRect(0, 0, canvas.width, canvas.height);
// 绘制蛇 ctx.fillStyle = '#2ecc71'; for (let segment of snake) { ctx.fillRect( segment.x * CELL_SIZE, segment.y * CELL_SIZE, CELL_SIZE - 1, CELL_SIZE - 1 ); }
// 绘制蛇头（不同颜色） ctx.fillStyle = '#27ae60'; ctx.fillRect( snake[0].x * CELL_SIZE, snake[0].y * CELL_SIZE, CELL_SIZE - 1, CELL_SIZE - 1 );
// 绘制食物 ctx.fillStyle = '#e74c3c'; ctx.beginPath(); ctx.arc( food.x * CELL_SIZE + CELL_SIZE / 2, food.y * CELL_SIZE + CELL_SIZE / 2, CELL_SIZE / 2 - 1, 0, Math.PI * 2 ); ctx.fill();}
// 游戏结束function gameOver() { clearInterval(gameInterval); isGameRunning = false; alert(`游戏结束！你的得分是: ${score}`);}
// 键盘控制document.addEventListener('keydown', e => { if (!isGameRunning) return;
switch (e.key) { case 'ArrowUp': if (direction !== 'down') nextDirection = 'up'; break; case 'ArrowDown': if (direction !== 'up') nextDirection = 'down'; break; case 'ArrowLeft': if (direction !== 'right') nextDirection = 'left'; break; case 'ArrowRight': if (direction !== 'left') nextDirection = 'right'; break; }});
// 开始游戏按钮startBtn.addEventListener('click', () => { if (isGameRunning) return; initGame(); isGameRunning = true; gameInterval = setInterval(gameLoop, GAME_SPEED);});
// 初始化游戏（但不自动开始）initGame();
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