javascript HTML5 canvas实现打砖块游戏

<div id="main">
 <!--将画布嵌在div块里面,使其可以居中-->
 <canvas id="liuming_canvas" width="300px" height="500px">
 </canvas>
</div>

var diamond = {
 x : 100, 
 y : 485,
 width : 100,
 height : 15,
 move : 10
}

var ball_impact = {
 x : 150,
 y : 465,
 r : 10,
 vx : 200,
 vy : 200
}

var diamond_impact = [];//定义存储击打小方块的数组
diamond_impact.length = 0;
var width_span = 25; // 任意两个小方块的横向间隔 
var height_span = 25; //任意两个小方块的水平间隔 
for(var i =1 ; i <=10 ; i++){//控制每行输出的小方块
 for(var j = 1 ; j < 10 ; j++){//输出每列的小方块 只有x轴和y轴的坐标不一样而已
 var diamond_impact_children = {
 x : width_span,
 y : height_span,
 width : 10,
 height : 10
 };
 width_span += 30;
 diamond_impact.push(diamond_impact_children); //将得到的小方块放在 diamond_impact 中，已被以后使用
 }
 height_span += 25;
 width_span = 25;
}

//键盘事件，获取当前在那个方向运动

var direction = "";
document.onkeydown = function (e) {
 if (e.keyCode == 37 ) direction = "left" ;
 if (e.keyCode == 39 ) direction = "right";
 if (e.keyCode == 38 ) direction = "up";
 if (e.keyCode == 40 ) direction = "down";
}
 
//定义四个方法来重绘制方块的位置 分别有 左、右、上、下

function move_right_diamond(){
 clear_diamond();//清除以前的方块
 init_canvas_background();//再次初始化画布 下同
 //重新绘制小方块的位置
 if(diamond.x + diamond.width >= canvas.width){ //判断方块是否已经到达最右端
 cxt.fillStyle = "#17F705";
 cxt.fillRect(diamond.x,diamond.y,diamond.width,diamond.height);
 }else{
 diamond.x += diamond.move;
 cxt.fillStyle = "#17F705";
 cxt.fillRect(diamond.x,diamond.y,diamond.width,diamond.height);
 }
}
//其余方法类似 

cxt.arc(ball_impact.x,ball_impact.y,ball_impact.r,0,Math.PI * 2,true);
cxt.closePath();
cxt.fill();
ball_impact.x += ball_impact.vx * cyc /1000;//改变其坐标的位置
ball_impact.y += ball_impact.vy * cyc /1000;

if(ball_impact.y + ball_impact.r >= canvas.height){
 cxt.fillStyle = "#FC0000";
 cxt.font = "bold 50px 微软雅黑";
 cxt.fillText("FAILURE！",30,250);
 diamond.move = 0;//不能移动板块
}

//判断是否与所有的小方块数相等
if(count_sum == 90){
 cxt.fillStyle = "#FCF205";
 cxt.font = "bold 50px 微软雅黑";
 cxt.fillText("SUCCESS！",20,250);//在画布上书写SUCCESS 
 diamond.move = 0;//不能移动板块
 ball_impact.vx =0;
 ball_impact.vy =0;
else{
 count_sum = 0;
}