1

我正在尝试获取下面的 jsfiddle 示例，以使黄色圆圈 div跟随鼠标 ，但限制为圆形而不是方形（div）。

http://jsfiddle.net/fhmkf/

JS 代码如下所示：

var mouseX = 0, mouseY = 0, limitX = 150-15, limitY = 150-15;
$(window).mousemove(function(e){
   mouseX = Math.min(e.pageX, limitX);
   mouseY = Math.min(e.pageY, limitY);
});

// 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) / 12;
    yp += (mouseY - yp) / 12;
    follower.css({left:xp, top:yp});

}, 30);

我了解代码的结构和方法，只是对语法不太熟悉！

更新limitX/Y和抛出额外变量radius的最佳位置在哪里？distance

4

1 回答 1

2

您可以通过计算距圆心的距离来做到这一点（二维距离用 计算）。然后检查距离是否大于您要约束的圆的半径。如果是，请缩小距离以匹配您的约束半径。Math.sqrt(x * x + y * y)

这是片段：

var mouseX = 0, mouseY = 0, limitX = 150-15, limitY = 150-15;
var centerX = limitX / 2, centerY = limitY / 2;
var radius = centerX;
$(window).mousemove(function(e) {
   var diffX = e.pageX - centerX;
   var diffY = e.pageY - centerY;

   // Get the mouse distance from the center
   var r = Math.sqrt(diffX * diffX + diffY * diffY);

   if (r > radius) {
     // Scale the distance down to length 1 
     diffX /= r;
     diffY /= r;

     // Scale back up to the radius
     diffX *= radius;
     diffY *= radius;
   }

   mouseX = centerX + diffX;
   mouseY = centerY + diffY;
});

这是完整的代码：http: //jsfiddle.net/fhmkf/

于 2013-10-05T16:59:57.803 回答