![[Canvas]英雄可以射箭了](https://image.shishitao.com:8440/aHR0cHM6Ly9ia3FzaW1nLmlrYWZhbi5jb20vdXBsb2FkL2NoYXRncHQtcy5wbmc%2FIQ%3D%3D.png?!?w=700&webp=1 "[Canvas]英雄可以射箭了")
点此下载源码并用浏览器观看。
图例：
![[Canvas]英雄可以射箭了](https://image.shishitao.com:8440/aHR0cHM6Ly9pbWcyMDE4LmNuYmxvZ3MuY29tL2Jsb2cvMTYyNDc1LzIwMTkwMy8xNjI0NzUtMjAxOTAzMDYxNjQ1MjA4MjQtNDY3OTY3MzEyLnBuZw%3D%3D.png?w=700&webp=1 "[Canvas]英雄可以射箭了")
代码：
<!DOCTYPE html>
<html lang="utf-8">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<head>
<title>地图加载 英雄可以射箭了 19.3.6 15:37 by:逆火狂飙 horn19782016@163.com</title>
<style>
#canvas{
background:#ffffff;
cursor:pointer;
margin-left:10px;
margin-top:10px;
-webkit-box-shadow:3px 3px 6px rgba(0,0,0,0.5);
-moz-box-shadow:3px 3px 6px rgba(0,0,0,0.5);
box-shadow:3px 3px 6px rgba(0,0,0,0.5);
}
#controls{
margin-top:10px;
margin-left:15px;
}
</style>
</head>
<body onload="init()">
<div id="controls">
<input id='animateBtn' type='button' value='开始'/>
</div>
<canvas id="canvas" width="160px" height="160px" >
出现文字表示你的浏览器不支持HTML5
</canvas>
</body>
</html>
<script type="text/javascript">
<!--
var paused=true;
animateBtn.onclick=function(e){
paused=! paused;
if(paused){
animateBtn.value="开始";
}else{
animateBtn.value="停止";
window.requestAnimationFrame(animate);
}
}
var ctx;// 绘图环境
var r;// 表盘半径
var terrain;
var hero;
var arrows;
function init(){
// init Canvas
var canvas=document.getElementById('canvas');
r=160;
canvas.width =2*r;
canvas.height=2*r;
ctx=canvas.getContext('2d');
terrain=new Terrain();
hero=new Hero();
arrows=new Array();
// 响应键盘事件
canvas.addEventListener('keydown', doKeyDown, true);
canvas.focus();
window.addEventListener('keydown', doKeyDown, true);
};
function draw(){
// Clear Canvas
ctx.clearRect(0,0,ctx.canvas.width,ctx.canvas.height);
ctx.fillStyle="#ECF5FF";
ctx.fillRect(0,0,ctx.canvas.width,ctx.canvas.height);
terrain.paint(ctx);
hero.paint(ctx);
for(var i=0;i<arrows.length;i++){
var arrow=arrows[i];
arrow.paint(ctx);
}
}
function animate(){
if(!paused){
draw();
window.requestAnimationFrame(animate); /// 让浏览器自行决定帧速率
}
}
function doKeyDown(e) {
var keyID = e.keyCode ? e.keyCode :e.which;
if(keyID === 38 || keyID === 87) { // up arrow and W
hero.move('up');
e.preventDefault();
}
if(keyID === 39 || keyID === 68) { // right arrow and D
hero.move('right');
e.preventDefault();
}
if(keyID === 40 || keyID === 83) { // down arrow and S
hero.move('down');
e.preventDefault();
}
if(keyID === 37 || keyID === 65) { // left arrow and A
hero.move('left');
e.preventDefault();
}
//alert('keyID='+keyID);
if(keyID === 32 ) { // SpaceBar
//alert(1);
var a=new Arrow(hero.x+16,hero.y+16,hero.direction);
arrows.push(a);
e.preventDefault();
}
}
//---------------------------------------------------地形类定义开始------------------------------------------------------------------->>
Terrain=function(){
this.files=["road.png","tree.png","home.png",];
this.maps=new Array(
[0,0,0,0,0,0,0,0,0,0],
[0,0,1,1,1,1,1,1,0,0],
[0,0,0,0,0,0,0,0,0,0],
[0,0,2,2,2,2,2,2,2,0],
[0,0,0,0,0,0,2,0,0,0],
[0,0,0,2,0,0,2,0,0,0],
[0,0,0,2,0,0,0,0,0,0],
[0,2,2,2,2,2,2,2,0,0],
[0,0,0,0,0,0,0,0,0,0],
[0,1,1,1,1,1,1,1,1,0],
);
}
Terrain.prototype={
files:[],
// Property
maps:0,
// method
paint:function(ctx){
for(var i=0;i<this.maps.length;i++){
var arr=this.maps[i];
for(var j=0;j<arr.length;j++){
var value=arr[j];
var img=new Image();
img.src=this.files[value];
ctx.drawImage(img,i*32,j*32);
}
}
},
getValue:function(i,j){
if(i<0 || i>=this.maps.length){
return undefined;
}
var arr=this.maps[i];
if(j<0 || j>=arr.length){
return undefined;
}
var value=arr[j];
return value;
},
}
//---------------------------------------------------地形类定义结束-------------------------------------------------------------------<<
//---------------------------------------------------英雄类定义开始------------------------------------------------------------------->>
Hero=function(){
this.files=["arrow_left.png","arrow_right.png","arrow_up.png","arrow_down.png",];
this.pngs=[
{left:0,top:10,width:40,height:40},
{left:0,top:66,width:40,height:40},
{left:0,top:120,width:40,height:40},
{left:0,top:180,width:40,height:40},
];
}
Hero.prototype={
files:[],
pngs:[],
x:160,
y:160,
xTo:160,
yTo:160,
step:32,
direction:'up',
// method
paint:function(ctx){
var img=new Image();
img.src='bowman.png';
var index=0;
if(this.direction=='up'){
index=3;
}
if(this.direction=='down'){
index=0;
}
if(this.direction=='left'){
index=1;
}
if(this.direction=='right'){
index=2;
}
var pos=this.pngs[index];
ctx.drawImage(img,pos.left,pos.top,pos.width,pos.height,this.x,this.y,pos.width,pos.height);
//ctx.drawImage(img,this.x,this.y);
},
move:function(direction){
this.direction=direction;
if(this.direction=='up'){
this.yTo-=this.step;
}
if(this.direction=='down'){
this.yTo+=this.step;
}
if(this.direction=='left'){
this.xTo-=this.step;
}
if(this.direction=='right'){
this.xTo+=this.step;
}
if(terrain.getValue(this.xTo/this.step,this.yTo/this.step)==0){
this.x=this.xTo;
this.y=this.yTo;
}else{
this.xTo=this.x;
this.yTo=this.y;
}
}
}
//---------------------------------------------------英雄类定义结束-------------------------------------------------------------------<<
//---------------------------------------------------箭矢类定义开始------------------------------------------------------------------->>
Arrow=function(x,y,direction){
this.x=x;
this.y=y;
this.direction=direction;
}
Arrow.prototype={
x:0,
y:0,
velocity:1,// 飞行速度
len:16,// 箭杆长
direction:'',
// method
paint:function(ctx){
var x1=this.x,y1=this.y;
if(this.direction=='up'){
this.y-=this.velocity;
y1=this.y-this.len;
x1=this.x;
}
if(this.direction=='down'){
this.y+=this.velocity;
y1=this.y+this.len;
x1=this.x;
}
if(this.direction=='left'){
this.x-=this.velocity;
x1=this.x-this.len;
y1=this.y;
}
if(this.direction=='right'){
this.x+=this.velocity;
x1=this.x+this.len;
y1=this.y;
}
//alert("this.x="+this.x);
//alert("this.y="+this.y);
//alert("x1="+x1);
//alert("y1="+y1);
ctx.beginPath();
ctx.lineWidth = 2;
ctx.strokeStyle = "#ff0000";
ctx.moveTo(this.x,this.y);
ctx.lineTo(x1,y1);
ctx.stroke();
ctx.closePath();
//alert(2);
},
}
//---------------------------------------------------箭矢类定义结束-------------------------------------------------------------------<<
//-->
</script>
2019年3月6日16点46分