function game() {
	// body...
	init();
	lasttime = Date.now();
	delttime = 0;
	game_loop();
}
function init () {
	//获得canvas contex
	//canvas1 用来处理鱼，土壤，UI，圆圈
	can1 = document.getElementById("canvas1");
	//canvas2 用来处理背景 海葵
	can2 = document.getElementById("canvas2");
	ctx1 = can1.getContext('2d');
	ctx2 = can2.getContext('2d');
	bgPic.src="../SRC/bg.jpg";//文件路径
	canWidth = can2.width;
	canHight = can2.height;
	dram_image();
}
function game_loop () {
	// body...比如鱼的游动
	//该函数要对浏览器适配
	requestAnimFrame(game_loop);//比setTimeout setInterval 科学 这个是根机器性能有关
	//console.log("game");
	var now = Date.now();
	delttime = now - lasttime;
	lasttime = now;
}
/*画canvas背景*/
function dram_image (){
	console.log(canHight,canWidth,bgPic);
	ctx2.drawImage(bgPic,0,0,canWidth,canHight);
}