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：
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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。
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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：
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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：
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(function(W){
"use strict"
var planWidth = 24,
planHeight = 24,
missleWidth = 70,
missleHeight = 70,
boomWidth = 60;
//精灵类
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);
}
}
}
}
// 精灵表绘制器
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;
}
}
}
//特制飞机精灵表绘制器
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;
}
if(sprite.rotateRight){
sprite.rotateAngle += sprite.rotateSpeed;
}
if(sprite.fire&&!sprite.painter.isActive){
sprite.painter.isActive = true;
this.shot(sprite);
}
},
shot:function(sprite){
this.addMissle(sprite , sprite.rotateAngle);
var missleAngle = 0.1
for(var i=1;i<sprite.fireLevel;i++){
this.addMissle(sprite , sprite.rotateAngle-i*missleAngle);
this.addMissle(sprite , sprite.rotateAngle+i*missleAngle);
}
var audio = document.getElementsByTagName("audio");
for(var i=0;i<audio.length;i++){
console.log(audio[i].paused)
if(audio[i].src.indexOf("shot")>=0&&audio[i].paused){
audio[i].play();
break;
}
}
},
addMissle:function(sprite , angle){
for(var j=0;j<missles.length;j++){
if(!missles[j].visible){
missles[j].left = sprite.left;
missles[j].top = sprite.top;
missles[j].rotateAngle = angle;
var missleSpeed = 20;
missles[j].velocityX = missleSpeed*Math.sin(-missles[j].rotateAngle);
missles[j].velocityY = missleSpeed*Math.cos(-missles[j].rotateAngle);
missles[j].visible = true;
break;
}
}
}
}
]
W.starBehavior = [
{execute:function(sprite,time){
if(sprite.top > canvas.height){
sprite.left = Math.random()*canvas.width;
sprite.top = Math.random()*canvas.height - canvas.height;
}
sprite.top += sprite.speed;
}}
]
W.starPainter = {
paint:function(sprite){
ctx.drawImage(sprite.cacheCanvas , sprite.left-sprite.width/2-sprite.lightLength , sprite.top-sprite.width/2-sprite.lightLength)
},
cache:function(sprite){
sprite.cacheCtx.save();
var opacity = 0.5,addopa = 1/sprite.lightLength;
sprite.cacheCtx.fillStyle = "rgba(255,255,255,0.8)";
sprite.cacheCtx.beginPath();
sprite.cacheCtx.arc(sprite.width/2+sprite.lightLength , sprite.width/2+sprite.lightLength , sprite.width/2 , 0 , 2*Math.PI);
sprite.cacheCtx.fill();
for(var i=1;i<=sprite.lightLength;i+=2){
opacity-=addopa;
sprite.cacheCtx.fillStyle = "rgba(255,255,255,"+opacity+")";
sprite.cacheCtx.beginPath();
sprite.cacheCtx.arc(sprite.width/2+sprite.lightLength , sprite.width/2+sprite.lightLength , sprite.width/2+i , 0 , 2*Math.PI);
sprite.cacheCtx.fill();
}
}
}
W.foodBehavior = [
{execute:function(sprite,time){
sprite.top += sprite.speed;
if(sprite.top > canvas.height+sprite.width){
sprite.visible = false;
}
}}
]
W.foodPainter = {
paint:function(sprite){
ctx.fillStyle = "rgba("+parseInt(Math.random()*255)+","+parseInt(Math.random()*255)+","+parseInt(Math.random()*255)+",1)"
ctx.font="15px 微软雅黑"
ctx.textAlign = "center";
ctx.textBaseline = "middle";
ctx.fillText(sprite.kind , sprite.left , sprite.top);
}
}
W.missleBehavior = [{
execute:function(sprite,time){
sprite.left -= sprite.velocityX;
sprite.top -= sprite.velocityY;
if(sprite.left<-missleWidth/2||sprite.top<-missleHeight/2||sprite.left>canvas.width+missleWidth/2||sprite.top<-missleHeight/2){
sprite.visible = false;
}
}
}];
W.misslePainter = {
paint:function(sprite){
var img = new Image();
img.src="../planGame/image/plasma.png"
ctx.drawImage(img , -missleWidth/2+1 , -missleHeight/2+1 , missleWidth , missleHeight);
}
}
W.badPlanBehavior = [{
execute:function(sprite,time){
if(sprite.top > canvas.height || !sprite.visible){
var random = Math.random();
if(point>=200&&point<400){
sprite.fullBlood = 150;
if(random<0.1){
sprite.badKind = 2;
sprite.fullBlood = 250;
}
}else if(point>=400&&point<600){
sprite.fullBlood = 250;
if(random<0.2){
sprite.badKind = 2;
sprite.fullBlood = 400;
}
if(random<0.1){
sprite.badKind = 3;
sprite.fullBlood = 600;
}
}else if(point>=600){
sprite.fullBlood = 500;
if(random<0.4){
sprite.badKind = 2;
sprite.fullBlood = 700;
}
if(random<0.2){
sprite.badKind = 3;
sprite.fullBlood = 1000;
}
}
sprite.visible = true;
sprite.blood = sprite.fullBlood;
sprite.left = Math.random()*(canvas.width-2*planWidth)+planWidth;
sprite.top = Math.random()*canvas.height - canvas.height;
}
sprite.top += sprite.speed;
},
shot:function(sprite){
this.addMissle(sprite , sprite.rotateAngle);
var missleAngle = 0.1
for(var i=1;i<sprite.fireLevel;i++){
this.addMissle(sprite , sprite.rotateAngle-i*missleAngle);
this.addMissle(sprite , sprite.rotateAngle+i*missleAngle);
}
},
addMissle:function(sprite , angle){
for(var j=0;j<missles.length;j++){
if(!missles[j].visible){
missles[j].left = sprite.left;
missles[j].top = sprite.top;
missles[j].rotateAngle = angle;
var missleSpeed = 20;
missles[j].velocityX = missleSpeed*Math.sin(-missles[j].rotateAngle);
missles[j].velocityY = missleSpeed*Math.cos(-missles[j].rotateAngle);
missles[j].visible = true;
break;
}
}
}
}];
W.badPlanPainter = {
paint:function(sprite){
var img = new Image();
img.src="../planGame/image/ship.png"
switch(sprite.badKind){
case 1:ctx.drawImage(img , 96 , 0 , planWidth , planWidth , -planWidth/2 , -planHeight/2 , planWidth , planWidth);
break;
case 2:ctx.drawImage(img , 120 , 0 , planWidth , planWidth , -planWidth/2 , -planHeight/2 , planWidth , planWidth);
break;
case 3:ctx.drawImage(img , 144 , 0 , planWidth , planWidth , -planWidth/2 , -planHeight/2 , planWidth , planWidth);
break;
}
ctx.strokeStyle = "#FFF";
ctx.fillStyle = "#F00";
var bloodHeight = 1;
ctx.strokeRect(-planWidth/2-1 , planHeight+bloodHeight+3 , planWidth+2 , bloodHeight+2);
ctx.fillRect(planWidth/2-planWidth*sprite.blood/sprite.fullBlood , planHeight+bloodHeight+3 , planWidth*sprite.blood/sprite.fullBlood , bloodHeight);
}
}
W.planSize = function(){
return {
&n
HTML
canvas
HTML5
