在調整動畫片段大小後旋轉不同

Question

我試圖在運行時實現旋轉和調整動畫片段大小的轉換方法，並且在重新計算旋轉以跟隨鼠標時出現問題。

我有一個方形影片剪輯，並在廣場的右下角，我正在聽鼠標事件和鼠標移動旋轉體對象（圓）我這樣做：

_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 

這個完美的作品只要我不修改對象的寬度或高度，但如果我修改，那麼對象的旋轉會有一個小的「跳躍」，這是我無法避免的。

我知道這是因爲event.stageX和even.stageY是不同的作爲rotator對象，與鼠標監聽器，已經移動resize事件後，但沒有線索如何避免「跳」。

請原諒我的英文不好

Answer 1

您需要圍繞其中心旋轉對象。

/** 
* 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); 

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