看专业码农直播写游戏

观看回放地址萧井陌的个人空间

Day One

播主代码：

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<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>game 1</title>
        <style media="screen">
            canvas {
                border: 1px black solid;
            }
        </style>
    </head>
    <body>
        <canvas id="id-canvas" width="400" height="300"></canvas>
<script>
var log = console.log.bind(console)
var imageFromPath = function(path) {
    var img = new Image()
    img.src = path
    return img
}
var Paddle = function() {
    var image = imageFromPath('paddle.png')
    var o = {
        image: image,
        x: 100,
        y: 250,
        speed: 15,
    }
    var paddle = o
    o.moveLeft = function() {
        paddle.x -= paddle.speed
    }
    o.moveRight = function() {
        paddle.x += paddle.speed
    }
    o.collide = function(ball) {
        if (ball.y + ball.image.height > o.y) {
            if (ball.x > o.x && ball.x < o.x + o.image.width) {
                log('相撞')
                return true
            }
        }
        return false
    }
    return o
}
var Ball = function() {
    var image = imageFromPath('ball.png')
    var o = {
        image: image,
        x: 100,
        y: 200,
        speedX: 10,
        speedY: 10,
        fired: false,
    }
    o.fire = function() {
        o.fired = true
    }
    o.move = function() {
        if (o.fired) {
            // log('move')
            if (o.x < 0 || o.x > 400) {
                o.speedX = -o.speedX
            }
            if (o.y < 0 || o.y > 300) {
                o.speedY = -o.speedY
            }
            // move
            o.x += o.speedX
            o.y += o.speedY
        }
    }
    return o
}
// 瓜
var GuaGame = function() {
    var g = {
        actions: {},
        keydowns: {},
    }
    var canvas = document.querySelector('#id-canvas')
    var context = canvas.getContext('2d')
    g.canvas = canvas
    g.context = context
    // draw
    g.drawImage = function(guaImage) {
        g.context.drawImage(guaImage.image, guaImage.x, guaImage.y)
    }
    // events
    window.addEventListener('keydown', function(event){
        g.keydowns[event.key] = true
    })
    window.addEventListener('keyup', function(event){
        g.keydowns[event.key] = false
    })
    //
    g.registerAction = function(key, callback) {
        g.actions[key] = callback
    }
    // timer
    setInterval(function(){
        // events
        var actions = Object.keys(g.actions)
        for (var i = 0; i < actions.length; i++) {
            var key = actions[i]
            if(g.keydowns[key]) {
                // 如果按键被按下, 调用注册的 action
                g.actions[key]()
            }
        }
        // update
        g.update()
        // clear
        context.clearRect(0, 0, canvas.width, canvas.height)
        // draw
        g.draw()
    }, 1000/30)
    return g
}
var __main = function() {
    var game = GuaGame()
    var paddle = Paddle()
    var ball = Ball()
    game.registerAction('a', function(){
        paddle.moveLeft()
    })
    game.registerAction('d', function(){
        paddle.moveRight()
    })
    game.registerAction('f', function(){
        ball.fire()
    })
    game.update = function() {
        ball.move()
        // 判断相撞
        if (paddle.collide(ball)) {
            // 这里应该调用一个 ball.反弹() 来实现
            ball.speedY *= -1
        }
    }
    game.draw = function() {
        // draw
        game.drawImage(paddle)
        game.drawImage(ball)
    }
}
__main()
</script>
    </body>
</html>

临摹代码：

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<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>game 1</title>
	<style type="text/css">
		canvas{
			border: 1px solid #eee;
		}
	</style>
</head>
<body>
	<canvas id="canvas" width="400" height="300"></canvas>
	<script type="text/javascript">
		// tool
		var log = console.log.bind()
		var imageFromPath = function (path) {
			var img = new Image()
			img.src = path
			return img
		}
		var Paddle = function () {
			var image = imageFromPath('https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=2323943722,3696495464&fm=26&gp=0.jpg')
			var o = {
				img: image,
				x: 200,
				y: 150,
				w: 120,
				h: 60,
				speed: 15,
			}
			o.moveLeft = function () {
				o.x -= o.speed
			}
			o.moveRight = function () {
				o.x += o.speed
			}
			o.collide = function (image) {
				if (image.y + image.img.height > o.y && image.y < o.y + o.img.height) { // 纵轴 球偏移和自高 大于 栏偏移
					// 横轴 球偏移 大于 栏偏移 并且 球偏移 小于 栏偏移和自宽
					if (image.x > o.x && image.x < o.x + o.img.width) {
						return true
					}
				}
				return false
			}
			return o
		}
		var Ball = function () {
			var image = imageFromPath('https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1504301500648&di=df06cc9f705e9355769e468413924d32&imgtype=jpg&src=http%3A%2F%2Fimg0.imgtn.bdimg.com%2Fit%2Fu%3D2346240780%2C32583404%26fm%3D214%26gp%3D0.jpg')
			var o = {
				img: image,
				x: 200,
				y: 150,
				w: 60,
				h: 30,
				speedX: 10,
				speedY: 10,
				fired: false,
			}
			o.fire = function () {
				o.fired = true
			}
			o.move = function () {
				if (o.fired) {
					if (o.x < 0 || o.x + o.w > 400) {
						o.speedX *= -1
					}
					if (o.y < 0 || o.y + o.h > 300) {
						o.speedY *= -1
					}
					o.x += o.speedX
					o.y += o.speedY
				}
			}
			return o
		}
		var Game = function () {
			var g = {
				actions: {},
				keydowns: {},
			}
			// 画布生成
			var canvas = document.querySelector("#canvas")
			var ctx = canvas.getContext("2d")
			g.canvas = canvas
			g.ctx = ctx
			// events
			window.addEventListener("keydown",function (e) {
				g.keydowns[e.key] = true
			})
			window.addEventListener("keyup",function (e) {
				g.keydowns[e.key] = false
			})
			g.registerAction = function (key,cb) {
				// 执行对应按键的对应方法
				g.actions[key] = cb
			}
			// clean canvas
			g.clean = function () {
				g.ctx.clearRect(0,0,g.canvas.width,g.canvas.height)
			}
			// draw image
			g.drawImage = function (image) {
				g.ctx.drawImage(image.img,image.x,image.y,image.w,image.h)
			}
			// 图片变化，一秒钟变化30次
			setInterval(function () {
				// Object.keys() 方法会返回一个由一个给定对象的自身可枚举属性组成的数组，数组中属性名的排列顺序和使用 for...in 循环遍历该对象时返回的顺序一致 （两者的主要区别是 一个 for-in 循环还会枚举其原型链上的属性）。
				var actions = Object.keys(g.actions)
				for (var i = 0; i < actions.length; i++) {
					var key = actions[i]
					// 根据状态决定是否执行
					if (g.keydowns[key]) {
						g.actions[key]()
					}
				}
				// update
				g.update()
				// clean
				g.clean()
				// draw
				g.draw()
			},1000/30)
			return g
		}
		// 主入口
		var __main = function () {
			var paddle = Paddle()
			var game = Game()
			var ball = Ball()
			game.update = function () {
				ball.move()
				// 碰撞
				if (paddle.collide(ball)) {
					ball.speedY *= -1
				}
			}
			game.draw = function () {
				game.drawImage(paddle)
				game.drawImage(ball)
			}
			game.registerAction('a',function () {
				paddle.moveLeft()
			})
			game.registerAction('d',function () {
				paddle.moveRight()
			})
			game.registerAction('f',function () {
				ball.fire()
			})
		}
		__main()
	</script>
</body>
</html>