参考：2D breakout game using pure JavaScript
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Gamedev Canvas Workshop</title>
<style>
* {
padding: 0;
margin: 0;
}
canvas {
background: #eee;
display: block;
margin: 0 auto;
}
</style>
</head>
<body>
<canvas id="myCanvas" width="480" height="320"></canvas>
<script>
// JavaScript code goes here
var canvas = document.getElementById('myCanvas');
// canvas 的 getContext 接口，用于获取 canvas 的上下文类型
// 可能的类型有 2d / webgl / webgl2 / bitmaprender
// ctx 是可以用来在 canvas 画布上绘制的工具
var ctx = canvas.getContext('2d');
// // 画一个红色实心正方形
// ctx.beginPath();
// ctx.rect(20, 40, 50, 50); // 左边距 上边距 宽 高
// ctx.fillStyle = "#FFFF00";
// ctx.fill();
// ctx.closePath();
// // 画一个绿色的实心圆
// ctx.beginPath();
// ctx.arc(240, 160, 20, 0, Math.PI, false);
// ctx.fillStyle = "green";
// ctx.fill();
// ctx.closePath();
// // 浅蓝色空心长方形
// ctx.beginPath();
// ctx.rect(160, 10, 100, 40);
// ctx.strokeStyle = "rgba(0, 0, 255, 0.5)";
// ctx.stroke();
// ctx.closePath();
// Move the ball
// 变量定义
var x = canvas.width / 2;
var y = canvas.height - 30; // 设置初始坐标为 (240, 290)
var dx = 2;
var dy = -2; // 设置初始移动方向为 45°
var ballRadius = 10; // 设置小球半径为 10
var paddleHeight = 10;
var paddleWidth = 75; // 设置挡板宽高
var paddleX = (canvas.width - paddleWidth) / 2; // 设置挡板初始 x 值
var rightPressed = false;
var leftPressed = false; // 设置左右按键状态存储变量
var brickRowCount = 3;
var brickColumnCount = 5;
var brickWidth = 75;
var brickHeight = 20;
var brickPadding = 10;
var brickOffsetTop = 30;
var brickOffsetLeft = 30; // 砖块组合变量定义
var score = 0; // 游戏得分数
var lives = 3; // 游戏生命数
// 将砖块放入一个二维数组
var bricks = [];
for (var c = 0; c < brickColumnCount; c++) {
bricks[c] = [];
for (var r = 0; r < brickRowCount; r++) {
bricks[c][r] = { x: 0, y: 0, status: 1 };
}
}
// 砖块绘制函数
function drawBricks() {
for (var c = 0; c < brickColumnCount; c++) {
for (var r = 0; r < brickRowCount; r++) {
if (bricks[c][r].status == 1) {
var brickX = (c * (brickWidth + brickPadding)) + brickOffsetLeft;
var brickY = (r * (brickHeight + brickPadding)) + brickOffsetTop;
bricks[c][r].x = brickX;
bricks[c][r].y = brickY;
ctx.beginPath();
ctx.rect(brickX, brickY, brickWidth, brickHeight);
ctx.fillStyle = "#0095DD";
ctx.fill();
ctx.closePath();
}
}
}
}
// 监听键盘左右键动作
document.addEventListener("keydown", keyDownHandler, false);
document.addEventListener("keyup", keyUpHandler, false);
document.addEventListener("mousemove", mouseMoveHandler, false);
function keyDownHandler(e) {
if (e.keyCode == 39) {
rightPressed = true;
}
else if (e.keyCode == 37) {
leftPressed = true;
}
}
function keyUpHandler(e) {
if (e.keyCode == 39) {
rightPressed = false;
}
else if (e.keyCode == 37) {
leftPressed = false;
}
}
function mouseMoveHandler(e) {
var relativeX = e.clientX - canvas.offsetLeft;
if (relativeX > 0 && relativeX < canvas.width) {
paddleX = relativeX - paddleWidth / 2;
}
}
// 碰撞检测函数
function collisionDetection() {
for (var c = 0; c < brickColumnCount; c++) {
for (var r = 0; r < brickRowCount; r++) {
var b = bricks[c][r];
if (b.status == 1) {
if (x > b.x && x < b.x + brickWidth && y > b.y && y < b.y + brickHeight) {
dy = -dy;
b.status = 0;
score++;
if (score == brickRowCount * brickColumnCount) {
alert("YOU WIN, CONGRATULATIONS!");
document.location.reload();
// clearInterval(interval); // Needed for Chrome to end game
}
}
}
}
}
}
// 分数绘制函数
function drawScore() {
ctx.font = "16px Arial";
ctx.fillStyle = "#0095DD";
ctx.fillText("Score: " + score, 8, 20);
}
// 生命绘制函数
function drawLives() {
ctx.font = "16px Arial";
ctx.fillStyle = "#0095DD";
ctx.fillText("Lives: " + lives, canvas.width - 65, 20);
}
// 小球的绘制函数，变量为 x y ballRadius
function drawBall() {
ctx.beginPath();
ctx.arc(x, y, ballRadius, 0, Math.PI * 2);
ctx.fillStyle = "#0095DD";
ctx.fill();
ctx.closePath();
}
// 挡板的绘制函数
function drawPaddle() {
ctx.beginPath();
ctx.rect(paddleX, canvas.height - paddleHeight, paddleWidth, paddleHeight);
ctx.fillStyle = "#0095DD";
ctx.fill();
ctx.closePath();
}
// 主绘制函数
function draw() {
// 小球关键帧
if (x + dx > canvas.width - ballRadius || x + dx < ballRadius) {
dx = -dx;
}
if (y + dy < ballRadius) {
dy = -dy;
} else if (y + dy > canvas.height - ballRadius - paddleHeight) {
if (x + ballRadius > paddleX && x - ballRadius < paddleX + paddleWidth) {
dy = -dy;
} else {
lives--;
if (!lives) {
alert("GAME OVER");
document.location.reload();
// clearInterval(interval); // Needed for Chrome to end game
}
else {
x = canvas.width / 2;
y = canvas.height - 30;
dx = 2;
dy = -2;
paddleX = (canvas.width - paddleWidth) / 2;
}
}
// alert("GAME OVER");
// document.location.reload();
// clearInterval(interval); // Needed for Chrome to end game
}
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawBricks();
drawBall();
x += dx;
y += dy;
// paddle 执行函数
if (rightPressed && paddleX < canvas.width - paddleWidth) {
paddleX += 7;
}
else if (leftPressed && paddleX > 0) {
paddleX -= 7;
}
drawPaddle();
collisionDetection();
drawScore();
drawLives();
requestAnimationFrame(draw);
}
// 主执行函数
draw();
</script>
</body>
</html>