科学教育

标题: 何星辰代码 [打印本页]

作者: 何星辰 时间: 2025-12-9 15:15
标题: 何星辰代码
const canvas = document.getElementById("gameCanvas");
const context = canvas.getContext("2d");
const startButton = document.getElementById("startButton");

const gridSize = 20;
let snake;
let food = {x: 0, y: 0};
let dx = gridSize;
let dy = 0;
let score = 0;
let game;

function drawSnake() {
context.clearRect(0, 0, canvas.width, canvas.height);
snake.forEach(part => {
      context.fillStyle = "green";
      context.fillRect(part.x, part.y, gridSize, gridSize);
});
}

function generateFood() {
food.x = Math.floor(Math.random() * (canvas.width / gridSize)) * gridSize;
food.y = Math.floor(Math.random() * (canvas.height / gridSize)) * gridSize;
}

function drawFood() {
context.fillStyle = "red";
context.fillRect(food.x, food.y, gridSize, gridSize);
}

function moveSnake() {
const head = {x: snake[0].x + dx, y: snake[0].y + dy};
snake.unshift(head);

if (head.x === food.x && head.y === food.y) {
      score++;
      generateFood();
} else {
      snake.pop();
}
}

function changeDirection(event) {
const keyPressed = event.keyCode;
// 用WASD控制方向
if (keyPressed === 65 && dx === 0) { // A - 向左
      dx = -gridSize;
      dy = 0;
}
if (keyPressed === 87 && dy === 0) { // W - 向上
      dx = 0;
      dy = -gridSize;
}
if (keyPressed === 68 && dx === 0) { // D - 向右
      dx = gridSize;
      dy = 0;
}
if (keyPressed === 83 && dy === 0) { // S - 向下
      dx = 0;
      dy = gridSize;
}
}

function gameLoop() {
moveSnake();
drawSnake();
drawFood();

const head = snake[0];

// 撞墙判断
if (head.x < 0 || head.x >= canvas.width || head.y < 0 || head.y >= canvas.height) {
      clearInterval(game);
      alert("Game Over! Your score is " + score);
}
}

startButton.addEventListener("click", () => {
snake = [
      {x: 0, y: 0},
      {x: gridSize, y: 0},
      {x: gridSize * 2, y: 0},
];
dx = gridSize;
dy = 0;
score = 0;
generateFood();
clearInterval(game); // 避免重复启动多个定时器
game = setInterval(gameLoop, 100);
});

document.addEventListener("keydown", changeDirection);

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