贪吃蛇小游戏(含详细思路及源代码)

自己写的一个简陋的贪吃蛇游戏,源代码如下:

  1 <!DOCTYPE html>
  2 <html lang="en">
  3 <head>
  4     <meta charset="UTF-8">
  5     <title>贪吃蛇小游戏</title>
  6     <style>
  7 *{margin:0; padding:0;}
  8 header {
  9     display: block;
 10     margin: 0 auto;
 11     width: 500px;
 12     text-align: center;
 13 }
 14 header h1 {
 15     font-family: Arial;
 16     font-weight: bold;
 17 }
 18 header #newGameButton {
 19     display: block;
 20     margin: 20px auto;
 21     width: 100px;
 22     padding: 10px 10px;
 23     background-color: #8f7a66;
 24     font-family: Arial;
 25     color: white;
 26     border-radius: 10px;
 27     text-decoration: none;
 28 }
 29 header #newGameButton:hover {
 30     background-color: #9f8b77;
 31 }
 32 header p {
 33     font-family: Arial;
 34     font-size: 25px;
 35     margin: 20px auto;
 36 }
 37 canvas{
 38     display:block; 
 39     border:medium double black;
 40     margin:4px auto;
 41 }
 42     </style>
 43 </head>
 44 <body>
 45     <header>
 46         <h1>贪吃蛇小游戏</h1>
 47         <a href="javascript:newgame();" id="newGameButton">New Game</a>
 48         <p>score:<span id="score">0</span></p>
 49     </header>
 50     <canvas id="canvas">
 51         Your browser doesn't support the <code>canvas</code> element.
 52     </canvas>
 53     <script>
 54     var CANVAS = document.getElementById("canvas");
 55 var CTX = CANVAS.getContext("2d");
 56 var SNAKE = new Array();    //用队列模拟蛇身
 57 var DIR = "right";                //用来控制蛇头的方向
 58 var SIZE = 20;                //蛇身的宽度
 59 var FOODX = 0;            //食物的x坐标
 60 var FOODY = 0;            //食物的y坐标
 61 var HEADX = 0;        //蛇头的x坐标
 62 var HEADY = 0;        //蛇头的y坐标
 63 var MAXWIDTH = 200;        //画布的高度
 64 var MAXHEIGHT = 200;    //画布的宽度
 65 var TIME = 400;            //蛇的速度
 66 var SCORE = 0;            //计算玩家分数
 67 var interval = null;
 68 
 69 CANVAS.width = MAXWIDTH;
 70 CANVAS.height = MAXHEIGHT;
 71 
 72 window.onload = function(){
 73     newgame();
 74 };
 75 document.getElementById("newGameButton").click(function(){
 76     newgame();
 77 });
 78 function newgame(){
 79     SNAKE = [];        //用队列模拟蛇身
 80     DIR = "right";    //用来控制蛇头的方向
 81     HEADX = 0;        //蛇头的x坐标
 82     HEADY = 0;        //蛇头的y坐标
 83     SCORE = 0;
 84     window.clearInterval(interval);
 85     interval = null;
 86     //初始化画布
 87     CTX.clearRect(0, 0, MAXWIDTH, MAXHEIGHT);
 88     //画一条蛇
 89     drawSnake();
 90     //放置食物
 91     setFood();
 92     //移动蛇
 93     interval = window.setInterval(move, TIME);
 94 
 95 }
 96 function move(){
 97     switch(DIR){
 98         case "up":HEADY = HEADY-SIZE;break;
 99         case "right":HEADX = HEADX+SIZE;break;
100         case "down":HEADY = HEADY+SIZE;break;
101         case "left":HEADX = HEADX-SIZE;break;
102     }
103     if(HEADX>MAXWIDTH-SIZE || HEADY>MAXHEIGHT-SIZE || HEADX<0 || HEADY<0){
104         alert("你的分数为:"+SCORE+"分,继续努力吧!失败原因:碰壁了.....");
105         window.location.reload();
106     }
107     for(var i=1;i<SNAKE.length;i++){
108         if(SNAKE[i][0] == SNAKE[0][0] && SNAKE[i][1] == SNAKE[0][1]){
109             alert("你的分数为:"+SCORE+"分,继续努力吧!失败原因:撞到自己了.....");
110             window.location.reload();
111         }
112     }
113     if(SNAKE.length == MAXWIDTH *MAXHEIGHT){
114         alert("好厉害!么么哒~");
115         window.location.reload();
116     }
117     moveIn(HEADX, HEADY);//移动一格
118 }
119 document.onkeydown = function(e) { //改变蛇方向
120     var code = e.keyCode - 37;
121     switch(code){
122         case 1 : DIR = "up";break;//
123         case 2 : DIR = "right";break;//
124         case 3 : DIR = "down";break;//
125         case 0 : DIR = "left";break;//
126     }
127 }
128 //=============================画一条蛇=======================================================
129 function drawSnake(){
130     CTX.fillStyle = "black";
131     //画蛇头
132     CTX.fillRect (HEADX, HEADY, SIZE, SIZE);
133     SNAKE.push([HEADX, HEADY]);
134     
135     //画蛇身
136     switch(DIR){
137         case "up": 
138             drawBody(HEADX, HEADY + SIZE, HEADX, HEADY + 2 * SIZE);
139             break;
140         case "right": 
141             drawBody(HEADX - SIZE, HEADY, HEADX - 2 * SIZE, HEADY);
142             break;
143         case "down": 
144             drawBody(HEADX, HEADY - SIZE, HEADX, HEADY - 2 * SIZE);
145             break;
146         case "left": 
147             drawBody(HEADX + SIZE, HEADY, HEADX + 2 * SIZE, HEADY);
148             break;
149     }
150 }
151 function drawBody(x1, y1, x2, y2){
152     CTX.fillRect (x1, y1, SIZE, SIZE); 
153     CTX.fillRect (x2, y2, SIZE, SIZE); 
154     SNAKE.push([x1, y1]);
155     SNAKE.push([x2, y2]);
156 }
157 //===========================放置食物==============================
158 function setFood(){
159     do{
160         FOODX = SIZE * Math.floor(Math.random() * MAXWIDTH / SIZE);
161         FOODY = SIZE * Math.floor(Math.random() * MAXHEIGHT / SIZE);
162     }while(foodInSnake());
163     CTX.fillStyle = "red";
164     CTX.fillRect (FOODX, FOODY, SIZE, SIZE);
165 }
166 function foodInSnake(){
167     for (var i = 0; i < SNAKE.length; i++) {
168         if(FOODX == SNAKE[i][0] && FOODY == SNAKE[i][1]){
169             return true;
170         }
171     }
172     return false;
173 }
174 //========================================移动一格===========================
175 function moveIn(x, y){
176     CTX.fillStyle = "black";
177     CTX.fillRect(x, y, SIZE, SIZE);//重画蛇头    
178     //把新蛇头添加到 SNAKE 数组
179     var newSnake = [[x, y]];
180     SNAKE = newSnake.concat(SNAKE);
181 
182     if(false == eatFood()){//如果没吃到食物,减少一格蛇尾    
183         var snakeTail = SNAKE.pop();//获得蛇尾位置
184         CTX.clearRect(snakeTail[0], snakeTail[1], SIZE, SIZE);//去掉蛇尾    
185     }
186 }
187 function eatFood(){
188     if(HEADX == FOODX && HEADY == FOODY){
189         CTX.fillStyle = "block";
190         CTX.fillRect (FOODX, FOODY, SIZE, SIZE);
191 
192         setFood();
193         SCORE++;
194         //$("#score").text(SCORE);
195         document.getElementById("score").innerHTML = SCORE;
196         return true;
197     }
198     return false;
199 }
200 
201     </script>
202 </html>
查看代码

效果图:

思路:

function newgame(){
    重置蛇和分数的数据;
    清除interval;
    初始化画布;
    画一条蛇;
    放置食物;
    使用定时器(setInterval)使蛇移动(move函数);
}
function move(){
    根据方向改变蛇头下一格将要到达的位置;
    判断游戏是否结束,以及显示结束的原因(包含输赢);
    蛇移动一格(moveIn函数);
}
对键盘的方向键作监控,当改变方向时,修改全局变量DIR的值(用于存储方向);
function moveIn(){
    在蛇头的前一格增加一格作为新的蛇头,并将蛇头的坐标作为第一个元素加入到代表蛇的数组中;
    if(没吃到食物){
        删除一格蛇尾,在画布中做相应改变;
    }
}

欢迎各位试玩和纠错~(*^__^*)

 需要注意的是,如果需要在JS中设定canvas中的宽度和高度,和设置其他CSS属性略有不同。CANVAS.width = MAXWIDTH;CANVAS.height = MAXHEIGHT; 

posted @ 2016-04-13 16:03  oSHYo  阅读(1244)  评论(0编辑  收藏  举报