之前在当耐特的DEMO里看到个打飞机的游戏，然后就把他的图片和音频扒了了下来。。。。自己凭着玩的心情重新写了一个。仅供娱乐哈。。。。。。我没有用框架，所有js都是自己写的。。。。。。所以就可以来当个简单的教程，对那些刚玩canvas的，或许能有些帮助，楼主玩canvas也不是很久，技术不是很好，请见谅哈。
闲话不多说，先上DEMO撒：飞机游戏 楼主写这个人纯碎娱乐，没想着写成多正式的游戏哈。
步入主题啦：打飞机游戏文件有index.html入口文件，allSprite.js精灵的逻辑处理文件，loading.js加载处理文件以及data.js（初始化的一些数据）。
首先，正常的游戏基本上都需要一个loading，loading页面就是用来预加载数据的，包括精灵表图片，音频等，因为这是个小游戏，要加载的就只有一些音频和图片。里面的加载代码主要就下面这些，其他是制作loading动画的，那个比较简单，就不贴了，如果有兴趣的直接在DEMO里看控制台就行了：
XML/HTML Code复制内容到剪贴板 loadImg:function(datas){ var _this = this; var dataIndex = 0; li(); function li(){ if(datas[dataIndex].indexOf("mp3")>=0){ var audio = document.createElement("audio"); document.body.appendChild(audio); audio.preload = "auto"; audio.src = datas[dataIndex]; audio.oncanplaythrough = function(){ this.oncanplaythrough = null; dataIndex++; if(dataIndex===datas.length){ _this.percent = 100; }else { _this.percent = parseInt(dataIndex/datas.length*100); li.call(_this); } } }else { preLoadImg(datas[dataIndex] , function(){ dataIndex++; if(dataIndex===datas.length){ _this.percent = 100; } else { _this.percent = parseInt(dataIndex/datas.length*100); li.call(_this); } }) } } }, //再贴出preLoadImg的方法 function preLoadImg(src , callback){ var img = new Image(); img.src = src; if(img.complete){ callback.call(img); }else { img.onload = function(){ callback.call(img); } } }
我先在data.js里面用一个数组保存文件的链接，然后判断这些链接是图片还是音频，如果是图片就用preLoadImg加载，预加载图片的代码很简单，就是new一个图片对象，然后把链接赋给它，加载完后再回调。音频的加载则是通过生成一个HTML5的audio dom对象，把链接赋给它，audio有一个事件“canplaythrough”，浏览器预计能够在不停下来进行缓冲的情况下持续播放指定的音频/视频时，会发生 canplaythrough 事件，也就是说当canplaythrough被调用时，音频就已经被加载的差不多了，可以进行下一个音频的加载了。就这样当把所有东西都加载完后，再进行回调，开始游戏。
游戏开始了，一个游戏，会需要很多的对象，所以我就统一写成了一个精灵对象，不同对象之间的每一帧的运动情况直接用behavior来分别编写就行了。
XML/HTML Code复制内容到剪贴板 W.Sprite = function(name , painter , behaviors , args){ if(name !== undefined) this.name = name; if(painter !== undefined) this.painter = painter; this.top = 0; this.left = 0; this.width = 0; this.height = 0; this.velocityX = 3; this.velocityY = 2; this.visible = true; this.animating = false; this.behaviors = behaviors; this.rotateAngle = 0; this.blood = 50; this.fullBlood = 50; if(name==="plan"){ this.rotateSpeed = 0.05; this.rotateLeft = false; this.rotateRight = false; this.fire = false; this.firePerFrame = 10; this.fireLevel = 1; }else if(name==="star"){ this.width = Math.random()*2; this.speed = 1*this.width/2; this.lightLength = 5; this.cacheCanvas = document.createElement("canvas"); thisthis.cacheCtx = this.cacheCanvas.getContext(2d); thisthis.cacheCanvas.width = this.width+this.lightLength*2; thisthis.cacheCanvas.height = this.width+this.lightLength*2; this.painter.cache(this); }else if(name==="badPlan"){ this.badKind = 1; this.speed = 2; this.rotateAngle = Math.PI; }else if(name==="missle"){ this.width = missleWidth; }else if(name==="boom"){ this.width = boomWidth; }else if(name==="food"){ this.width = 40; this.speed = 3; this.kind = "LevelUP" } this.toLeft = false; this.toTop = false; this.toRight = false; this.toBottom = false; this.outArcRadius = Math.sqrt((this.width/2*this.width/2)*2); if(args){ for(var arg in args){ this[arg] = args[arg]; } } } Sprite.prototype = { constructor:Sprite, paint:function(){ if(this.name==="badPlan"){this.update();} if(this.painter !== undefined && this.visible){ if(this.name!=="badPlan") { this.update(); } if(this.name==="plan"||this.name==="missle"||this.name==="badPlan"){ ctx.save(); ctx.translate(this.left , this.top); ctx.rotate(this.rotateAngle); this.painter.paint(this); ctx.restore(); }else { this.painter.paint(this); } } }, update:function(time){ if(this.behaviors){ for(var i=0;i<this.behaviors.length;i++){ this.behaviors[i].execute(this,time); } } } }
写出精灵类后，就可以通过编写每个的painter以及behavior来生成不同的对象了。接下来就是写painter了，painter分成两种，一种是普通的painter，一种就是精灵表painter，因为像爆炸动画，飞机开枪动画，都不是一张图片就能搞定的，所以就需要用到精灵表了：
而绘制这些就要为他们定制一个精灵表绘制器，下面这个是最简单的精灵表绘制器，针对游戏的复杂性可以相对的修改精灵表写法，直到合适，不过原理都大同小异，就是小修小改而已：
XML/HTML Code复制内容到剪贴板 var SpriteSheetPainter = function(cells){ this.cells = cells || []; this.cellIndex = 0; } SpriteSheetPainter.prototype = { advance:function(){ if(this.cellIndex === this.cells.length-1){ this.cellIndex = 0; } else this.cellIndex++; }, paint:function(sprite){ var cell = this.cells[this.cellIndex]; context.drawImage(spritesheet , cell.x , cell.y , cell.w , cell.h , sprite.left , sprite.top , cell.w , cell.h); } } 而普通的绘制器就更简单了，直接写一个painter，把要画的什么东西都写进去就行了。
有了精灵类和精灵表绘制器后，我们就可以把星星，飞机，子弹，爆炸对象都写出来了：下面是整个allSprite.js的代码：
JavaScript Code复制内容到剪贴板 (function(W){ "use strict" var planWidth = 24, planHeight = 24, missleWidth = 70, missleHeight = 70, boomWidth = 60; W.Sprite = function(name , painter , behaviors , args){ if(name !== undefined) this.name = name; if(painter !== undefined) this.painter = painter; this.top = 0; this.left = 0; this.width = 0; this.height = 0; this.velocityX = 3; this.velocityY = 2; this.visible = true; this.animating = false; this.behaviors = behaviors; this.rotateAngle = 0; this.blood = 50; this.fullBlood = 50; if(name==="plan"){ this.rotateSpeed = 0.05; this.rotateLeft = false; this.rotateRight = false; this.fire = false; this.firePerFrame = 10; this.fireLevel = 1; }else if(name==="star"){ this.width = Math.random()*2; this.speed = 1*this.width/2; this.lightLength = 5; this.cacheCanvas = document.createElement("canvas"); this.cacheCtx = this.cacheCanvas.getContext(2d); this.cacheCanvas.width = this.width+this.lightLength*2; this.cacheCanvas.height = this.width+this.lightLength*2; this.painter.cache(this); }else if(name==="badPlan"){ this.badKind = 1; this.speed = 2; this.rotateAngle = Math.PI; }else if(name==="missle"){ this.width = missleWidth; }else if(name==="boom"){ this.width = boomWidth; }else if(name==="food"){ this.width = 40; this.speed = 3; this.kind = "LevelUP" } this.toLeft = false; this.toTop = false; this.toRight = false; this.toBottom = false; this.outArcRadius = Math.sqrt((this.width/2*this.width/2)*2); if(args){ for(var arg in args){ this[arg] = args[arg]; } } } Sprite.prototype = { constructor:Sprite, paint:function(){ if(this.name==="badPlan"){this.update();} if(this.painter !== undefined && this.visible){ if(this.name!=="badPlan") { this.update(); } if(this.name==="plan"||this.name==="missle"||this.name==="badPlan"){ ctx.save(); ctx.translate(this.left , this.top); ctx.rotate(this.rotateAngle); this.painter.paint(this); ctx.restore(); }else { this.painter.paint(this); } } }, update:function(time){ if(this.behaviors){ for(var i=0;i<this.behaviors.length;i++){ this.behaviors[i].execute(this,time); } } } } W.SpriteSheetPainter = function(cells , isloop , endCallback , spritesheet){ this.cells = cells || []; this.cellIndex = 0; this.dateCount = null; this.isloop = isloop; this.endCallback = endCallback; this.spritesheet = spritesheet; } SpriteSheetPainter.prototype = { advance:function(){ this.cellIndex = this.isloop?(this.cellIndex===this.cells.length-1?0:this.cellIndex+1):(this.cellIndex+1); }, paint:function(sprite){ if(this.dateCount===null){ this.dateCount = new Date(); }else { var newd = new Date(); var tc = newd-this.dateCount; if(tc>40){ this.advance(); this.dateCount = newd; } } if(this.cellIndex<this.cells.length || this.isloop){ var cell = this.cells[this.cellIndex]; ctx.drawImage(this.spritesheet , cell.x , cell.y , cell.w , cell.h , sprite.left-sprite.width/2 , sprite.top-sprite.width/2 , cell.w , cell.h); } else if(this.endCallback){ this.endCallback.call(sprite); this.cellIndex = 0; } } } W.controllSpriteSheetPainter = function(cells , spritesheet){ this.cells = cells || []; this.cellIndex = 0; this.dateCount = null; this.isActive = false; this.derection = true; this.spritesheet = spritesheet; } controllSpriteSheetPainter.prototype = { advance:function(){ if(this.isActive){ this.cellIndex++; if(this.cellIndex === this.cells.length){ this.cellIndex = 0; this.isActive = false; } } }, paint:function(sprite){ if(this.dateCount===null){ this.dateCount = new Date(); }else { var newd = new Date(); var tc = newd-this.dateCount; if(tc>sprite.firePerFrame){ this.advance(); this.dateCount = newd; } } var cell = this.cells[this.cellIndex]; ctx.drawImage(this.spritesheet , cell.x , cell.y , cell.w , cell.h , -planWidth/2 , -planHeight/2 , cell.w , cell.h); } } W.planBehavior = [ {execute:function(sprite,time){ if(sprite.toTop){ sprite.top = sprite.top<planHeight/2? sprite.top : sprite.top-sprite.velocityY; } if(sprite.toLeft){ sprite.left = sprite.left<planWidth/2? sprite.left : sprite.left-sprite.velocityX; } if(sprite.toRight){ sprite.left = sprite.left>canvas.width-planWidth/2? sprite.left : sprite.left+sprite.velocityX; } if(sprite.toBottom){ sprite.top = sprite.top>canvas.height-planHeight/2? sprite.top : sprite.top+sprite.velocityY; } if(sprite.rotateLeft){ sprite.rotateAngle -= sprite.rotateSpeed; } <
