看了两遍视频了  代码也没错误  大鱼就是显示不出来是怎么了？

看了两遍视频了  代码也没错误  大鱼就是显示不出来是怎么了？

var momObj=function()
{
    this.x;
    this.y;
    this.bigEye=new Image();
    this.bigBody=new Image();
    this.bigTail=new Image();
}
momObj.prototype.init=function()
{
    this.x=canWidth*0.5;
    this.y=canHeight*0.5;
    this.bigEye.src="./src/bigEye0.png";
    this.bigBody.src="./src/bigSwim0.png";
    this.bigTail.src="./src/bigTail0.png";
}
momObj.prototype.draw=function()
{
    ctx1.save();
    ctx1.translate(this.x,this.y);
    ctx1.drawImage(this.bigEye,-this.bigEye.width*0.5,-this.bigEye.height*0.5);
    ctx1.drawImage(this.bigBody,-this.bigBody.width*0.5,-this.bigBody.height*0.5);
    ctx1.drawImage(this.bigTail,-this.bigTail.width*0.5,-this.bigTail.height*0.5);
    ctx1.restore();
}