HTML5 Canvas 星空战机游戏开发全解析
一、游戏介绍
这是一款基于HTML5 Canvas开发的2D射击游戏，具有以下特色功能：
- 🚀 纯代码绘制的星空动态背景
- ✈️ 三种不同特性的敌人类型
- 🎮 键盘控制的玩家战机
- 📊 完整的分数统计和排行榜系统
- ⚙️ 三种难度可选
二、核心代码解析
1. 游戏初始化
const canvas = document.getElementById('gameCanvas');
const ctx = canvas.getContext('2d');
let game = {
// 游戏状态对象
stars: [], // 星星数组
bullets: [], // 玩家子弹
enemies: [], // 敌人数组
score: 0, // 当前分数
level: 1, // 当前关卡
player: { // 玩家对象
x: canvas.width/2,
y: canvas.height-100,
width: 40,
health: 100
}
};
2. 游戏主循环
function gameLoop() {
// 1. 清空画布
ctx.clearRect(0, 0, canvas.width, canvas.height);
// 2. 更新游戏状态
updateGame();
// 3. 绘制所有元素
drawBackground();
drawPlayer();
drawEnemies();
drawBullets();
// 4. 请求下一帧
requestAnimationFrame(gameLoop);
}
3. 玩家控制实现
// 键盘事件监听
const keys = {};
window.addEventListener('keydown', e => keys[e.key] = true);
window.addEventListener('keyup', e => keys[e.key] = false);
// 玩家移动逻辑
function movePlayer() {
if (keys['ArrowLeft']) {
// 左移限制：不能超出左边界
game.player.x = Math.max(game.player.width/2, game.player.x - 8);
}
if (keys['ArrowRight']) {
// 右移限制：不能超出右边界
game.player.x = Math.min(canvas.width-game.player.width/2, game.player.x + 8);
}
if (keys[' ']) {
// 空格键射击
fireBullet();
}
}
三、关键技术点
1. 敌人系统设计
| 敌人类型 | 速度 | 生命值 | 分数 | 特性 |
|---|---|---|---|---|
| 基础型 | 3 | 1 | 10 | 普通移动 |
| 快速型 | 5 | 1 | 20 | 高速移动 |
| 坦克型 | 2 | 5 | 50 | 高生命值 |
2. 碰撞检测优化
采用圆形碰撞检测算法：
function checkCollision(bullet, enemy) {
const dx = bullet.x - enemy.x;
const dy = bullet.y - enemy.y;
const distance = Math.sqrt(dx * dx + dy * dy);
return distance < (bullet.radius + enemy.width/2);
}
3. 排行榜实现
使用localStorage存储数据：
function saveHighScore(name, score) {
const scores = JSON.parse(localStorage.getItem('highScores')) || [];
scores.push({ name, score });
scores.sort((a, b) => b.score - a.score);
localStorage.setItem('highScores', JSON.stringify(scores.slice(0, 10)));
}
四、完整代码
<!DOCTYPE html>
<html>
<head>
<title>星空战机</title>
<style>
body { margin: 0; overflow: hidden; font-family: Arial, sans-serif; }
canvas { display: block; }
#ui {
position: absolute;
top: 20px;
left: 20px;
color: white;
font-size: 16px;
text-shadow: 2px 2px 4px rgba(0,0,0,0.5);
}
#menu {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
background: rgba(0, 0, 0, 0.8);
padding: 20px;
border-radius: 10px;
color: white;
text-align: center;
}
button {
padding: 10px 20px;
margin: 10px;
font-size: 16px;
cursor: pointer;
border: none;
border-radius: 5px;
background: #3498db;
color: white;
}
</style>
</head>
<body>
<canvas id="gameCanvas"></canvas>
<div id="ui"></div>
<div id="menu">
<h1>星空战机</h1>
<p>选择难度：</p>
<button onclick="startGame('easy')">简单</button>
<button onclick="startGame('normal')">普通</button>
<button onclick="startGame('hard')">困难</button>
<div id="highScores"></div>
</div>
<script>
// 初始化
const canvas = document.getElementById('gameCanvas');
const ctx = canvas.getContext('2d');
const ui = document.getElementById('ui');
const menu = document.getElementById('menu');
const highScores = document.getElementById('highScores');
let game = {
stars: [],
bullets: [],
enemyBullets: [],
enemies: [],
powerups: [],
explosions: [],
score: 0,
level: 1,
difficulty: 'normal',
player: {
x: 0, // 初始位置会在 startGame 中设置
y: 0, // 初始位置会在 startGame 中设置
width: 40,
height: 60,
speed: 8,
canShoot: true,
health: 100,
weapon: 'normal',
shield: 0
},
running: false
};
// 调整画布大小
function resizeCanvas() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
if (game.running) {
// 如果游戏运行中调整画布大小，重置玩家位置
game.player.x = canvas.width / 2;
game.player.y = canvas.height - 100;
}
}
resizeCanvas();
window.addEventListener('resize', resizeCanvas);
// 显示高分榜
function showHighScores() {
const scores = JSON.parse(localStorage.getItem('highScores')) || [];
highScores.innerHTML = '<h2>高分榜</h2>' +
scores.map((score, i) =>
`<div>${i + 1}. ${score.name}: ${score.score}</div>`
).join('');
}
// 开始游戏
function startGame(difficulty) {
game = {
...game,
stars: [],
bullets: [],
enemyBullets: [],
enemies: [],
powerups: [],
explosions: [],
score: 0,
level: 1,
difficulty,
player: {
...game.player,
x: canvas.width / 2, // 初始位置在画布中央
y: canvas.height - 100, // 初始位置在画布底部
health: difficulty === 'easy' ? 150 : difficulty === 'normal' ? 100 : 75,
weapon: 'normal',
shield: 0
},
running: true
};
menu.style.display = 'none';
createStars();
gameLoop();
}
// 游戏结束
function gameOver() {
game.running = false;
const name = prompt('游戏结束！请输入你的名字：');
if (name) {
saveHighScore(name, game.score);
}
menu.style.display = 'block';
showHighScores();
}
// 保存高分
function saveHighScore(name, score) {
const scores = JSON.parse(localStorage.getItem('highScores')) || [];
scores.push({ name, score });
scores.sort((a, b) => b.score - a.score);
localStorage.setItem('highScores', JSON.stringify(scores.slice(0, 10)));
}
// 生成星星
function createStars() {
for (let i = 0; i < 200; i++) {
game.stars.push({
x: Math.random() * canvas.width,
y: Math.random() * canvas.height,
size: Math.random() * 3,
alpha: Math.random()
});
}
}
// 绘制背景
function drawBackground() {
const gradient = ctx.createLinearGradient(0, 0, 0, canvas.height);
gradient.addColorStop(0, "#000428");
gradient.addColorStop(1, "#004e92");
ctx.fillStyle = gradient;
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = "white";
game.stars.forEach(star => {
ctx.globalAlpha = star.alpha;
ctx.beginPath();
ctx.arc(star.x, star.y, star.size, 0, Math.PI * 2);
ctx.fill();
});
ctx.globalAlpha = 1;
}
// 绘制玩家
function drawPlayer() {
// 护盾
if (game.player.shield > 0) {
ctx.strokeStyle = `rgba(0, 255, 255, ${game.player.shield / 100})`;
ctx.lineWidth = 2;
ctx.beginPath();
ctx.arc(game.player.x, game.player.y, 40, 0, Math.PI * 2);
ctx.stroke();
}
// 机身
ctx.fillStyle = "#4a90e2";
ctx.beginPath();
ctx.moveTo(game.player.x, game.player.y);
ctx.lineTo(game.player.x - game.player.width / 2, game.player.y + game.player.height);
ctx.lineTo(game.player.x + game.player.width / 2, game.player.y + game.player.height);
ctx.closePath();
ctx.fill();
// 机翼
ctx.fillStyle = "#2c3e50";
ctx.fillRect(game.player.x - 25, game.player.y + 20, 50, 15);
// 推进器火焰
ctx.fillStyle = `hsl(${Math.random() * 30 + 30}, 100%, 50%)`;
ctx.beginPath();
ctx.ellipse(game.player.x, game.player.y + game.player.height + 5, 8, 15, 0, 0, Math.PI * 2);
ctx.fill();
}
// 生成敌人
function createEnemy() {
const enemyTypes = ['basic', 'fast', 'tank'];
const type = enemyTypes[Math.floor(Math.random() * enemyTypes.length)];
game.enemies.push({
x: Math.random() * canvas.width,
y: -50,
width: 40,
height: 40,
speed: type === 'fast' ? 5 : type === 'tank' ? 2 : 3,
health: type === 'tank' ? 5 : 1,
type
});
}
// 敌人射击
function enemyShoot() {
game.enemies.forEach(enemy => {
if (Math.random() < 0.02) {
game.enemyBullets.push({
x: enemy.x,
y: enemy.y + enemy.height / 2,
speed: 5
});
}
});
}
// 碰撞检测
function checkCollisions() {
// 玩家子弹击中敌人
game.bullets.forEach((bullet, bIndex) => {
game.enemies.forEach((enemy, eIndex) => {
if (bullet.x > enemy.x - enemy.width / 2 &&
bullet.x < enemy.x + enemy.width / 2 &&
bullet.y > enemy.y - enemy.height / 2 &&
bullet.y < enemy.y + enemy.height / 2) {
game.score += 10;
game.bullets.splice(bIndex, 1);
enemy.health -= 1;
if (enemy.health <= 0) {
game.enemies.splice(eIndex, 1);
}
}
});
});
// 敌人子弹击中玩家
game.enemyBullets.forEach((bullet, index) => {
if (bullet.x > game.player.x - game.player.width / 2 &&
bullet.x < game.player.x + game.player.width / 2 &&
bullet.y > game.player.y - game.player.height / 2 &&
bullet.y < game.player.y + game.player.height / 2) {
game.player.health -= 10;
game.enemyBullets.splice(index, 1);
if (game.player.health <= 0) {
gameOver();
}
}
});
}
// 更新关卡
function updateLevel() {
if (game.score >= game.level * 1000) {
game.level++;
}
}
// 游戏主循环
function gameLoop() {
if (!game.running) return;
// 更新游戏状态
updateGame();
// 绘制游戏元素
drawBackground();
drawPlayer();
drawBullets();
drawEnemies();
drawUI();
requestAnimationFrame(gameLoop);
}
// 更新游戏状态
function updateGame() {
// 更新星星位置
game.stars.forEach(star => {
star.y += 2;
if (star.y > canvas.height) {
star.y = 0;
star.x = Math.random() * canvas.width;
}
});
// 更新子弹位置
game.bullets.forEach(bullet => bullet.y -= 10);
game.bullets = game.bullets.filter(bullet => bullet.y > 0);
// 更新敌人子弹位置
game.enemyBullets.forEach(bullet => bullet.y += bullet.speed);
game.enemyBullets = game.enemyBullets.filter(bullet => bullet.y < canvas.height);
// 更新敌人位置
game.enemies.forEach(enemy => enemy.y += enemy.speed);
game.enemies = game.enemies.filter(enemy => enemy.y < canvas.height + 50);
// 生成敌人
if (Math.random() < 0.03) {
createEnemy();
}
// 敌人射击
enemyShoot();
// 碰撞检测
checkCollisions();
// 更新关卡
updateLevel();
}
// 绘制UI
function drawUI() {
ui.innerHTML = `
<div>分数: ${game.score}</div>
<div>生命值: ${game.player.health}</div>
<div>护盾: ${game.player.shield}</div>
<div>武器: ${game.player.weapon}</div>
<div>关卡: ${game.level}</div>
`;
}
// 绘制子弹
function drawBullets() {
ctx.fillStyle = "#ffdd57";
game.bullets.forEach(bullet => {
ctx.beginPath();
ctx.arc(bullet.x, bullet.y, 5, 0, Math.PI * 2);
ctx.fill();
});
ctx.fillStyle = "#e74c3c";
game.enemyBullets.forEach(bullet => {
ctx.beginPath();
ctx.arc(bullet.x, bullet.y, 5, 0, Math.PI * 2);
ctx.fill();
});
}
// 绘制敌人
function drawEnemies() {
ctx.fillStyle = "#e74c3c";
game.enemies.forEach(enemy => {
ctx.beginPath();
ctx.ellipse(enemy.x, enemy.y, enemy.width / 2, enemy.height / 2, 0, 0, Math.PI * 2);
ctx.fill();
});
}
// 键盘控制
const keys = {};
window.addEventListener('keydown', e => keys[e.key] = true);
window.addEventListener('keyup', e => keys[e.key] = false);
// 玩家移动
function movePlayer() {
if (keys['ArrowLeft'] && game.player.x > game.player.width / 2) {
game.player.x -= game.player.speed;
}
if (keys['ArrowRight'] && game.player.x < canvas.width - game.player.width / 2) {
game.player.x += game.player.speed;
}
if (keys[' '] && game.player.canShoot) {
game.bullets.push({ x: game.player.x, y: game.player.y });
game.player.canShoot = false;
setTimeout(() => game.player.canShoot = true, 200);
}
}
// 运行游戏
setInterval(movePlayer, 1000 / 60);
showHighScores();
</script>
</body>
</html>
五、扩展方向
- 添加BOSS战系统
- 实现武器升级机制
- 加入粒子爆炸特效
- 添加背景音乐和音效
