避免光标在网页上的默认位置为（0,0）

Question

在下面的jsfiddle中我试图将黄色和红色圆圈设置为最初出现在中心，而不是移动到光标的初始假定位置 - 这是（0,0）因为光标还没有出现在页面的实际屏幕上（如果我猜对了）。

http://jsfiddle.net/fhmkf/220/

我有没有办法定义光标的初始位置 - 就是在计算(window).mousemove(function(e){...时 - 尤其是e.pageX和e.pageY？

js看起来像这样：

var Circle = function(container, follower, r){
    var center = {
        x: $(container).width()/2 - r, 
        y: $(container).height()/2 - r
    };
    var distanceThreshold = $(container).width()/2 - r;
    var mouseX = 0, mouseY = 0;

    $(window).mousemove(function(e){ 
        var d = {
            x: e.pageX - center.x,
            y: e.pageY - center.y
        };
        var distance = Math.sqrt(d.x*d.x + d.y*d.y);
        if (distance < distanceThreshold) {
            mouseX = e.pageX;
            mouseY = e.pageY;
        } else {
            mouseX = d.x / distance * distanceThreshold + center.x;
            mouseY = d.y / distance * distanceThreshold + center.y;
        }
    });

    // cache the selector
    var follower = $(follower);
    var xp = 0, yp = 0;
    var loop = setInterval(function(){
        // change 12 to alter damping higher is slower
        xp += (mouseX - xp) / 2;
        yp += (mouseY - yp) / 2;
        follower.css({left:xp, top:yp});

    }, 30);
};

var c1 = new Circle(".container", "#follower", 15);
var c2 = new Circle(".container2", "#follower2", 25);