JS配合canvas實作貪吃蛇小游戲-有解無憂

@Descripttion:
@Author: zhangJunQing
@Date: 2021-04-25
@LastEditors: zhangJunQing

機會是留給有準備的人的！

這是五一前一周周六，吃了午飯，突然想做個貪吃蛇，沒有為啥，也不知道為啥想做這個，馬上氪：

首先我們看一下效果圖

在這里插入圖片描述
我們先將簡單的樣式搞出來：

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>canvas貪吃蛇游戲</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        html,
        body {
            width: 100vw;
            height: 100vh;
        }

        #canvas {
            background: black;
        }

        button {
            position: absolute;
            border: none;
            background: #ccc;
            color: black;
            font-weight: bold;
            font-size: 30px;
            width: 350px;
            height: 80px;
            line-height: 80px;
            text-align: center;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            transition: all 1s;
        }

        .but {
            top: 20%;
            width: 800px;
        }
    </style>
</head>

<body>
    <canvas id="canvas"></canvas>
    <button>開始游戲</button>
    <button class="but">因為打開的視窗大小不是小方塊的倍數，所以可能存在誤差</button>
</body>

</html>

頁面內上只有canvas和兩個按鈕

然后我們需要考慮貪吃蛇這條蛇是怎么運動的，特點是
控制舌頭，蛇身會走舌頭走過的路線，
1 我們需要給canvas定制寬高
2 兩個button顯示隱藏
3 獲取canvas畫筆
4 貪吃蛇分為舌頭和蛇身

		let canvas = document.getElementById('canvas')
        let btn = document.getElementsByTagName('button')[0]
        let btn1 = document.getElementsByTagName('button')[1]
        canvas.width = document.getElementsByTagName('body')[0].clientWidth
        canvas.height = document.getElementsByTagName('body')[0].clientHeight
        let ctx = canvas.getContext('2d')
        //蛇頭
        let SnackTop = []
        //蛇身體
        let SnackList = []
        //蛇整體
        let SnackFonlyList = [...SnackTop, ...SnackList]

創建蛇這個建構式
//X向右 y向下 -x 向左 -y 上

//隨機顏色
let colorList = ["#33B5E5", "#0099CC", "#AA66CC", "#9933CC", "#99CC00", "#669900", "#FFBB33", "#FF8800", "#FF4444", "#CC0000"]

function Snack(x1 = 30, y1 = 30, x2 = 30, y2 = 30, color) {
			//這幾個屬性在使用canvas畫方塊的時候會使用
            this.x1 = x1;  //x軸坐標
            this.x2 = x2;  //x坐標長度
            this.y1 = y1;  //y軸左邊
            this.y2 = y2;  //y坐標長度
            this.color = color || colorList[Math.floor(Math.random() * 10)]
            this.direction = 'x'  //X向右 y向下 -x 向左  -y 上
            this.paceSoon = 30  
        }

創建兩個個蛇身一個舌頭物件陣列，并且讓他從30，30這個坐標開始創建


 	let x1 = 30, y1 = 30, x2 = 30, y2 = 30;
	//生成三個
        function getSanck() {
            for (let i = 0; i < 3; i++) {
                x1 += 30;
                SnackList.length != 2 ? SnackList.push(new Snack(x1, y1, x2, y2)) : SnackTop.push(new Snack(x1, y1, x2, y2))
            }
        }

SnackTop 里面一個Snack實體化物件，SnackList里面兩個
我們是用 +=30 生成的，所以我們需要將整個陣列顛倒，才能是我們整個蛇身的順序，這里好好思考一下

 SnackList = SnackList.reverse()

下面要做的就是讓他渲染到頁面上，屬性都有了直接加方法

		//創建蛇身和舌頭方法
        Snack.prototype.RectFun = function () {
            ctx.beginPath();
            ctx.fillStyle = this.color
            ctx.fillRect(this.x1, this.y1, this.x2, this.y2);
            ctx.stroke();
        }

讓他動起來的方法，就是一直改變他的x1,y1

 Snack.prototype.Update = function () {
            if (this.direction == 'x') {
                this.x1 += this.paceSoon 
            } else if (this.direction == 'y') {
                this.y1 += this.paceSoon 
            } else if (this.direction == '-x') {
                this.x1 -= this.paceSoon
            } else if (this.direction == '-y') {
                this.y1 -= this.paceSoon
            }
        }

通過鍵盤事件改變方向并控制不能直接掉頭

        //添加鍵盤按下時間 并且不能直接掉頭
        window.addEventListener('keydown', function (e) {
            if (e.keyCode == '39') {
                SnackTop[0].direction == '-x' ? '' : SnackTop[0].direction = 'x'
                // console.log('右')
            } else if (e.keyCode == '40') {//下 40
                SnackTop[0].direction == '-y' ? '' : SnackTop[0].direction = 'y'
                // console.log('下')
            } else if (e.keyCode == '37') {//左 37
                SnackTop[0].direction == 'x' ? '' : SnackTop[0].direction = '-x'
                // console.log('-x')
            } else if (e.keyCode == '38') {//右 39
                SnackTop[0].direction == 'y' ? '' : SnackTop[0].direction = '-y'
                // console.log('-y')
            }
        })

當然現在還不能實作蛇身移動，再搞一個方法，讓第一個蛇身跟著蛇頭，其他蛇身跟著上一個蛇身，讓他們的狀態一直改變（也就是屬性值改變）

 Snack.prototype.directionFun = function (index) {
            if (index == 0) {
                if (SnackTop[0].direction == 'x') {
                    this.x1 = SnackTop[0].x1 - 30
                    this.direction = 'x'
                    this.y1 = SnackTop[0].y1
                } else if (SnackTop[0].direction == 'y') {
                    this.direction = 'y'
                    this.x1 = SnackTop[0].x1
                    this.y1 = SnackTop[0].y1 - 30
                } else if (SnackTop[0].direction == '-x') {
                    this.direction = '-x'
                    this.x1 = SnackTop[0].x1 + 30
                    this.y1 = SnackTop[0].y1
                } else if (SnackTop[0].direction == '-y') {
                    this.direction = '-y'
                    this.y1 = SnackTop[0].y1 + 30
                    this.x1 = SnackTop[0].x1
                }
            } else {
                if (list[index - 1].direction == 'x') {
                    this.x1 = list[index - 1].x1
                    this.y1 = list[index - 1].y1
                } else if (list[index - 1].direction == 'y') {
                    this.x1 = list[index - 1].x1
                    this.y1 = list[index - 1].y1
                } else if (list[index - 1].direction == '-x') {
                    this.x1 = list[index - 1].x1
                    this.y1 = list[index - 1].y1
                } else if (list[index - 1].direction == '-y') {
                    this.y1 = list[index - 1].y1
                    this.x1 = list[index - 1].x1
                }
            }
        }

這里面的list就是上一次每一個蛇身的狀態
我們使用深拷貝進行取狀態

list = JSON.parse(JSON.stringify(SnackList))

這個時候我們的蛇頭和蛇身就可以跟隨運動了
下一步就是食物
我們還是需要給他一個建構式和一個生成食物的方法

//食物
        function Eat(x1, y1, x2, y2) {
            this.x1 = x1;
            this.y1 = y1;
            this.x2 = x2;
            this.y2 = y2;
            this.color = colorList[Math.floor(Math.random() * 10)]
        }
        Eat.prototype.RectFunE = function () {
            ctx.beginPath();
            ctx.fillStyle = this.color
            ctx.fillRect(this.x1, this.y1, this.x2, this.y2);
            ctx.stroke();
        }

我們需要判斷一下當前頁面有沒有食物，沒有得話生成

//食物
            if (EatList.length == 0)
                EatList.push(new Eat(MathRandomFun(120, canvas.width - 120), MathRandomFun(150, canvas.height - 90), x2, y2))
            EatList.map(item => {
                item.RectFunE()
            })

MathRandomFun方法是生成一個亂數，并且使蛇方塊的大小倍數

//生成食物亂數 
        function MathRandomFun(min, max) {
            let num = Math.floor((max - min) * Math.random() + min)
            if (num % 30 == 0) {
                return num
            } else {
                return MathRandomFun(min, max)
            }
        }

判斷有沒有碰到食物，碰到蛇身加一，添加到陣列，顏色為吃的食物顏色

  //判斷舌頭和食物的位置資訊
  //SnackTop  蛇頭
  //EatList   食物
 if (SnackTop[0].x1 == EatList[0].x1 && SnackTop[0].y1 == EatList[0].y1) {
       //添加蛇身體
       SnackList.push(new Snack(list[list.length - 1].x1, list[list.length - 1].y1, x2, y2, EatList[0].color))
      EatList.length = 0
    }

設定邊界
//任意一遍超出界限就是游戲失敗

if (SnackTop[0].x1 < -30 || SnackTop[0].x1 > canvas.width || SnackTop[0].y1 < -30 || SnackTop[0].y1 > canvas.height) {
                clearInterval(timeID)
                // alert('游戲結束')
                ctx.clearRect(0, 0, canvas.width, canvas.height)
                console.log("=========")
                btn.style.opacity = 1
                btn1.style.opacity = 1
                return false
            }

整體代碼如下：

<!--
 * @Descripttion: 
 * @Author: zhangJunQing
 * @Date: 2021-04-25 
 * @LastEditors: zhangJunQing  1
-->
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>canvas貪吃蛇游戲</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        html,
        body {
            width: 100vw;
            height: 100vh;
        }

        #canvas {
            background: black;
        }

        button {
            position: absolute;
            border: none;
            background: #ccc;
            color: black;
            font-weight: bold;
            font-size: 30px;
            width: 350px;
            height: 80px;
            line-height: 80px;
            text-align: center;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            transition: all 1s;
        }

        .but {
            top: 20%;
            width: 800px;
        }
    </style>
</head>

<body>
    <canvas id="canvas"></canvas>
    <button>開始游戲</button>
    <button class="but">因為打開的視窗大小不是小方塊的倍數，所以可能存在誤差</button>
    <script>
        let canvas = document.getElementById('canvas')
        let btn = document.getElementsByTagName('button')[0]
        let btn1 = document.getElementsByTagName('button')[1]
        canvas.width = document.getElementsByTagName('body')[0].clientWidth
        canvas.height = document.getElementsByTagName('body')[0].clientHeight
        let ctx = canvas.getContext('2d')
        //蛇頭
        let SnackTop = []
        //蛇身體
        let SnackList = []
        //蛇整體
        let SnackFonlyList = [...SnackTop, ...SnackList]
        //食物陣列
        let EatList = []
        //存放上次狀態的陣列
        let list = []
        //定時器id
        let timeID = null;

        let colorList = ["#33B5E5", "#0099CC", "#AA66CC", "#9933CC", "#99CC00", "#669900", "#FFBB33", "#FF8800", "#FF4444", "#CC0000"]
        let x1 = 30, y1 = 30, x2 = 30, y2 = 30;
        btn.addEventListener('click', function () {
            if (btn.innerHTML == '開始游戲') {
                btn.style.opacity = 0
                btn1.style.opacity = 0
                setTimeout(function () {
                    requestAnimation()
                    btn.innerHTML = '觸碰邊界，游戲結束'
                    timeID = setInterval(requestAnimation, 100)
                }, 1000)
            }
        })
        function Snack(x1 = 30, y1 = 30, x2 = 30, y2 = 30, color) {
            this.x1 = x1;
            this.x2 = x2;
            this.y1 = y1;
            this.y2 = y2;
            this.color = color || colorList[Math.floor(Math.random() * 10)]
            this.direction = 'x'  //X向右 y向下 -x 向左  -y 上
            this.paceSoon = 30
            
        }
        Snack.prototype.RectFun = function () {
            ctx.beginPath();
            ctx.fillStyle = this.color
            ctx.fillRect(this.x1, this.y1, this.x2, this.y2);
            ctx.stroke();
        }
        Snack.prototype.Update = function () {
            if (this.direction == 'x') {
                this.x1 += this.paceSoon 
            } else if (this.direction == 'y') {
                this.y1 += this.paceSoon 
            } else if (this.direction == '-x') {
                this.x1 -= this.paceSoon
            } else if (this.direction == '-y') {
                this.y1 -= this.paceSoon
            }
        }
        Snack.prototype.directionFun = function (index) {
            if (index == 0) {
                if (SnackTop[0].direction == 'x') {
                    this.x1 = SnackTop[0].x1 - 30
                    this.direction = 'x'
                    this.y1 = SnackTop[0].y1
                } else if (SnackTop[0].direction == 'y') {
                    this.direction = 'y'
                    this.x1 = SnackTop[0].x1
                    this.y1 = SnackTop[0].y1 - 30
                } else if (SnackTop[0].direction == '-x') {
                    this.direction = '-x'
                    this.x1 = SnackTop[0].x1 + 30
                    this.y1 = SnackTop[0].y1
                } else if (SnackTop[0].direction == '-y') {
                    this.direction = '-y'
                    this.y1 = SnackTop[0].y1 + 30
                    this.x1 = SnackTop[0].x1
                }
            } else {
                if (list[index - 1].direction == 'x') {
                    this.x1 = list[index - 1].x1
                    this.y1 = list[index - 1].y1
                } else if (list[index - 1].direction == 'y') {
                    this.x1 = list[index - 1].x1
                    this.y1 = list[index - 1].y1
                } else if (list[index - 1].direction == '-x') {
                    this.x1 = list[index - 1].x1
                    this.y1 = list[index - 1].y1
                } else if (list[index - 1].direction == '-y') {
                    this.y1 = list[index - 1].y1
                    this.x1 = list[index - 1].x1
                }
            }
        }
        //食物
        function Eat(x1, y1, x2, y2) {
            this.x1 = x1;
            this.y1 = y1;
            this.x2 = x2;
            this.y2 = y2;
            this.color = colorList[Math.floor(Math.random() * 10)]
        }
        Eat.prototype.RectFunE = function () {
            ctx.beginPath();
            ctx.fillStyle = this.color
            ctx.fillRect(this.x1, this.y1, this.x2, this.y2);
            ctx.stroke();
        }
        //生成八個
        function getSanck() {
            for (let i = 0; i < 3; i++) {
                x1 += 30;
                SnackList.length != 2 ? SnackList.push(new Snack(x1, y1, x2, y2)) : SnackTop.push(new Snack(x1, y1, x2, y2))
            }
        }
        getSanck()
        //生成食物亂數 
        function MathRandomFun(min, max) {
            let num = Math.floor((max - min) * Math.random() + min)
            if (num % 30 == 0) {
                return num
            } else {
                return MathRandomFun(min, max)
            }
        }
        SnackList = SnackList.reverse()
        // 生成n個正方形  和一個食物
        function requestAnimation() {

            list = JSON.parse(JSON.stringify(SnackList))
            ctx.clearRect(0, 0, canvas.width, canvas.height)
            //食物
            if (EatList.length == 0)
                EatList.push(new Eat(MathRandomFun(120, canvas.width - 120), MathRandomFun(150, canvas.height - 90), x2, y2))
            EatList.map(item => {
                item.RectFunE()
            })
            //判斷舌頭和食物的位置資訊
            //SnackTop  舌頭
            //EatList   食物
            if (SnackTop[0].x1 == EatList[0].x1 && SnackTop[0].y1 == EatList[0].y1) {
                //添加蛇身體
                SnackList.push(new Snack(list[list.length - 1].x1, list[list.length - 1].y1, x2, y2, EatList[0].color))
                EatList.length = 0
            }
            SnackTop.map(item => {
                item.RectFun()
                item.Update()
            })
            SnackList.map((item, index) => {
                item.RectFun()
                item.directionFun(index)
            })
            if (SnackTop[0].x1 < -30 || SnackTop[0].x1 > canvas.width || SnackTop[0].y1 < -30 || SnackTop[0].y1 > canvas.height) {
                console.log(SnackTop[0], 'SnackTop[0]')
                clearInterval(timeID)
                // alert('游戲結束')
                ctx.clearRect(0, 0, canvas.width, canvas.height)
                console.log("=========")
                btn.style.opacity = 1
                btn1.style.opacity = 1
                return false
            }
        }

        //添加鍵盤按下時間 并且不能直接掉頭
        window.addEventListener('keydown', function (e) {
            if (e.keyCode == '39') {
                SnackTop[0].direction == '-x' ? '' : SnackTop[0].direction = 'x'
                // console.log('右')
            } else if (e.keyCode == '40') {//下 40
                SnackTop[0].direction == '-y' ? '' : SnackTop[0].direction = 'y'
                // console.log('下')
            } else if (e.keyCode == '37') {//左 37
                SnackTop[0].direction == 'x' ? '' : SnackTop[0].direction = '-x'
                // console.log('-x')
            } else if (e.keyCode == '38') {//右 39
                SnackTop[0].direction == 'y' ? '' : SnackTop[0].direction = '-y'
                // console.log('-y')
            }
        })

    </script>
</body>

</html>

里面的設計思路肯定還有很多種，還有其他思路的大佬歡迎評論，一起探討，一起加油，

轉載請註明出處，本文鏈接：https://www.uj5u.com/qita/280283.html

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