Question

我正在尝试实现转换方法以在运行时旋转和调整动画片段的大小，并且在重新计算旋转以跟随鼠标时出现问题。

我在广场的右下角有一个方形的动画片段和一个旋转物体（一个圆圈），我正在听鼠标事件和鼠标移动我这样做：

_rotation  = -(Math.atan2((event.stageX - this.x  ), (event.stageY - this.y ))) * 180/Math.PI;

this.rotation = rotation + 45;//this is because my rotator object is on right,bottom corner

只要我不修改对象的宽度或高度，这就行得很完美，但是如果我修改那么对象的旋转会有一个小的“跳跃”，这是我无法避免的。

我知道这是由于event.stageX和even.stageY不同，因为旋转器对象（带有鼠标侦听器的对象）在调整大小事件后已经移动但是没有线索如何避免“跳转”。

请原谅我的英文不好

Answer 1

您需要围绕其中心旋转对象。

/**
* Rotates the object based on its center
* Parameters: @obj => the object to rotate
* @ rotation => angle to rotate
* */
public function RotateAroundCenter(obj:Object, rotation:Number):void
   {
        var bound:Rectangle = new Rectangle();
        // get the bounded rectangle of objects
        bound = obj.getRect(this);

        // calculate mid poits
        var midx1:Number = bound.x + bound.width/2;
        var midy1:Number = bound.y + bound.height/2;

        // assign the rotation
        obj.rotation = rotation;

        // assign the previous mid point as (x,y)
        obj.x = midx1;
        obj.y = midy1;

        // get the new bounded rectangle of objects
        bound = obj.getRect(this);

        // calculate new mid points
        var midx2:Number = bound.x + bound.width/2;
        var midy2:Number = bound.y + bound.height/2;

        // calculate differnece between the current mid and (x,y) and subtract
        //it to position the object in the previous bound.
        var diff:Number = midx2 - obj.x;
        obj.x -= diff;
        diff = midy2 - obj.y;
        obj.y -= diff;
}

用法：

_rotation  = -(Math.atan2((event.stageX - this.x  ), (event.stageY - this.y ))) * 180/Math.PI;
RotateAroundCenter(this,  rotation + 45);

选中此link

调整动画片段后，旋转功能会有所不同

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