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一个基于HTML5的canvas的js面向对象贪吃蛇

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作者 正文
   发表时间:2011-09-23  

下面是一个使用canvas API加JS面向对象的方式编写的一个贪吃蛇的简单实现,实现了穿墙、吃食物后智能加速,还缺少障碍物,地图切换,还有就是太丑了,有兴趣的朋友可以修改一下,我觉得这个还算好扩展,特地贴出来大家讨论研究,算法我写得差劲,权当抛砖引玉之用。

<!DOCTYPE HTML>
<html>
    <head>
       <meta charset="utf-8">
       <title>Asphyre</title>
       <script>
       		var AsphyreNode = function(x, y, w, h){
				this.x = x;
				this.y = y;
				this.w = w;
				this.h = h;
				this.equals = function(node) {
					if(this.x === node.x && this.y === node.y)
						return true;
					return false;
				}
			};
       		function Asphyre(farm, x, y, speed, initNodes){ 		//对贪吃蛇的描述,相当于实现一个蛇类
				var self = this;
				this.perform = null;	//定时器引用
				this.speed = speed;
				this.speedParam = speed * initNodes;		//蛇移动的速度
				this.nodeSize = 10;		//蛇每一节的大小
				this.nodes = [];		//节点数
				this.initNodes = initNodes;
				this.farm = farm;
				this.x = x;
				this.y = y;
				this.direction = 10;	//表示向右,初始方向
				this.left = -10,this.right = 10;
				this.down = 1, this.up = -1;
				document.onkeypress = function(event) {
					event = event || window.event;
					var code = event.keyCode || event.charCode();
					var isException = false;
					switch(code) {
						case 37: //向左
							if(self.direction + self.left){
								self.direction = self.left;
							} else isException = true;
							break;
						case 38: //向上
							if(self.direction + self.up){
								self.direction = self.up;
							} else isException = true;
							break;
						case 39: //向右
							if(self.direction + self.right){
								self.direction = self.right;
							} else isException = true;
							break;
						case 40: //向下
							if(self.direction + self.down){
								self.direction = self.down;
							} else isException = true;
							break;
					}
					if(isException){
						alert("方向异常,不能沿反方向后退!");
					}
				}
			};
			Asphyre.prototype = {
				init: function(){
					var self = this, farm = this.farm, x = this.x, y = this.y;
					this.nodes = [];
					for(var i = 0; i < this.initNodes; i ++) {
						this.nodes[i] = new AsphyreNode(this.x - i * 10, this.y, this.nodeSize, this.nodeSize);
					}
					this.farm.food = this.farm.newFood(this);
					this.farm.repaint(this);
				},
				drawNodes: function(context){	//绘制设身体
					var self = this;
					context.fillStyle = "#000000";
					context.strokeStyle = "#ffffff";
					for(var i = 0; i < this.nodes.length; i ++) {
						context.fillRect(this.nodes[i].x, this.nodes[i].y, this.nodeSize, this.nodeSize);
						context.strokeRect(this.nodes[i].x, this.nodes[i].y, this.nodeSize, this.nodeSize);
					}
				},
				eatFood: function() {//吃食物
					var self = this;
					self.nodes.unshift(self.farm.food);
					self.farm.food = self.farm.newFood(self);
					self.refreshSpeed();
				},
				start: function(){//开始
					var self = this;
					self.init();
					if(!self.perform)
						self.perform = setInterval(self.go, self.speed, this);
				},
				continueRun: function(){	//继续
					var self = this;
					if(!self.perform)
						self.perform = setInterval(self.go, self.speed, this);
				},
				stop: function(){//结束
					var self = this;
					if(!!self.perform)
						clearInterval(self.perform);
					self.perform = null;
					self.farm.clear();
				},
				pause: function() {	//暂停
					var self = this;
					if(!!self.perform)
						clearInterval(self.perform);
					self.perform = null;
				},
				go: function(param){//沿着当前方向前进
					var self = param;
					switch(self.direction) {
						case -1: 	//上
							if(self.nodes[0].equals(self.farm.food)) {//吃到食物,少走一步
								self.farm.food.y -= self.nodeSize
								self.eatFood();
								self.farm.repaint(self);
								return;
							}
							var varluable = self.nodes[0].y - self.nodeSize;
							if(varluable < 0)
								varluable = self.farm.farmElem.height - self.nodeSize
							self.nodes.unshift(new AsphyreNode(self.nodes[0].x, varluable, self.nodeSize, self.nodeSize));
							self.nodes.pop();
							break;
						case 1: 	//下
							if(self.nodes[0].equals(self.farm.food)) {//吃到食物,少走一步
								self.farm.food.y += self.nodeSize
								self.eatFood();
								self.farm.repaint(self);
								return;
							}
							var varluable = self.nodes[0].y + self.nodeSize;
							if(varluable > self.farm.farmElem.height - self.nodeSize)
								varluable = 0;
							self.nodes.unshift(new AsphyreNode(self.nodes[0].x, varluable, self.nodeSize, self.nodeSize));
							self.nodes.pop();
							break;
						case -10: 	//左
							if(self.nodes[0].equals(self.farm.food)) {//吃到食物,少走一步
								self.farm.food.x -= self.nodeSize
								self.eatFood();
								self.farm.repaint(self);
								return;
							}
							var varluable = self.nodes[0].x - self.nodeSize;
							if(varluable < 0)
								varluable = self.farm.farmElem.width - self.nodeSize;
							self.nodes.unshift(new AsphyreNode(varluable, self.nodes[0].y, self.nodeSize, self.nodeSize));
							self.nodes.pop();
							break;
						case 10: 	//右
							if(self.nodes[0].equals(self.farm.food)) {//吃到食物,少走一步
								self.farm.food.x += self.nodeSize
								self.eatFood();
								self.farm.repaint(self);
								return;
							}
							var varluable = self.nodes[0].x + self.nodeSize;
							if(varluable > self.farm.farmElem.width - self.nodeSize)
								varluable = 0;
							self.nodes.unshift(new AsphyreNode(varluable, self.nodes[0].y, self.nodeSize, self.nodeSize));
							self.nodes.pop();
							break;
					}
					self.farm.repaint(self);
					for(var i = 1; i < self.nodes.length; i ++) {
						if(self.nodes[0].equals(self.nodes[i])) {//吃到身体,死亡
							self.die();
							break;
						}
					}
				},
				refreshSpeed: function() {	//吃到食物后调整速度的算法
					var self = this;
					this.speed = Math.round(this.speedParam / this.nodes.length);
					self.stop();
					self.continueRun();
				},
				die: function() {	//蛇咬到自己死了
					var self = this, context = this.farm.context;
					self.pause();
					document.getElementById("pause").disabled = true;
					document.getElementById("continue").disabled = true;
					document.getElementById("stop").disabled = true;
					self.drawOver(context);
				},
				drawOver: function(context) {
					context.save();
					context.font="60px impact";
					context.fillStyle="#000000";
					context.textAlign="center";
					context.fillText("GAME OVER!",250,250);
				}
			};
			
			var Farm = function(farmId){			//对农场的描述,相当于实现农场类
				this.farmElem = document.getElementById(farmId);
				this.context = this.farmElem.getContext("2d");
				this.food = null;
				this.init();
			};
			Farm.prototype = {
				init: function(){	//初始化农场
					var self = this, farm = this.farmElem, context = this.context;
					var w = farm.width,h = farm.height;
					context.fillStyle = "#E8FFFF";
					context.strokeStyle = "#000000";
                	context.fillRect(0, 0, w, h);
					context.strokeRect(0, 0, w, h)
				},
				clear: function() {	//清理农场
					var self = this, farm = this.farmElem, context = this.context;
					var w = farm.width,h = farm.height;
					context.fillStyle = "#E8FFFF";
					context.strokeStyle = "#000000";
                	context.fillRect(0, 0, w, h);
					context.strokeRect(0, 0, w, h)
				},
				repaint: function(snake) {	//重绘农场
					var self = this;
					self.clear();
					self.drowFood(snake);
					snake.drawNodes(snake.farm.context);
				},
				newFood: function(snake) {	//农场为蛇生成食物
					var x,y;
					var flag = true;
					k:
					while(flag) {
						x = Math.round(Math.random() * (this.farmElem.width-10) / 10) * 10;
						y = Math.round(Math.random() * (this.farmElem.height-10) / 10) * 10;
						for(var i = 0; i < snake.nodes.length; i ++) {
							if(snake.nodes[i].x === x && snake.nodes[i].y === y){//食物在蛇的身体上
								break k;
							}
						}
						flag = false;
					}
					return new AsphyreNode(x, y, snake.nodeSize, snake.nodeSize);
				},
				drowFood: function() {	//为毒蛇画饼
					this.context.fillStyle = "#FEF045";
					this.context.strokeStyle = "#ffffff";
					this.context.fillRect(this.food.x, this.food.y, this.food.w, this.food.h);
					this.context.strokeRect(this.food.x, this.food.y, this.food.w, this.food.h);
					
				}
			}
			var Game = function(){			//主程序,用于启动游戏
				this.snake = new Asphyre(new Farm("canvas"), 200, 200, 500, 5);
			};
			Game.prototype = {
				start: function(){
					this.snake.start();
				},
				stop: function() {
					this.snake.stop();
				},
				pause: function() {
					this.snake.pause();
				},
				continueRun: function() {
					this.snake.continueRun();
				}
			}
       </script>
    </head>
    <body>
        <div id="wrapper" style="text-align: center;">
            <canvas id="canvas" width="500"height="500"></canvas><br/>
        	<input type="button" value="新游戏" id="start"/>&nbsp;&nbsp;&nbsp;&nbsp;
			<input type="button" value="继续" id="continue" disabled="true"/>&nbsp;&nbsp;&nbsp;&nbsp;
			<input type="button" value="结束" id="stop" disabled="true"/>&nbsp;&nbsp;&nbsp;&nbsp;
			<input type="button" value="暂停" id="pause" disabled="true"/>&nbsp;&nbsp;&nbsp;&nbsp;
		</div>
		<script>
			var game = new Game();
				document.getElementById("start").onclick = function(){
					game.start();
					document.getElementById("continue").disabled = true;
					document.getElementById("pause").disabled = false;
					document.getElementById("stop").disabled = false;
				};
				document.getElementById("stop").onclick = function(){
					game.stop();
					document.getElementById("start").disabled = false;
					document.getElementById("pause").disabled = true;
					document.getElementById("continue").disabled = true;
					this.disabled = true;
				};
				document.getElementById("pause").onclick = function(){
					game.pause();
					document.getElementById("stop").disabled = true;
					document.getElementById("continue").disabled = false;
					document.getElementById("start").disabled = false;
					this.disabled = true;
				};
				document.getElementById("continue").onclick = function(){
					game.continueRun();
					this.disabled = true;
					document.getElementById("stop").disabled = false;
					document.getElementById("start").disabled = false;
					document.getElementById("pause").disabled = false;
				};
		</script>
    </body>
</html>


 

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