Flash AS3环绕舞台

我试着让flash从舞台中心画一条线，然后在舞台周围增加。不知道我会用什么数学来做这个。到目前为止，我有一条线延伸到某个点，但不确定如何改变该点，使其围绕我的舞台的任何维度旋转

到目前为止，我有：

var linetox=0;
var linetoy=0;
var _stage=this;
var _stage_center_x = stage.stageWidth/2;
var _stage_center_y = stage.stageHeight/2;
trace(_stage_center_x);
function enterframe(e:Event):void {
    linetox+=10;
    linetoy+=10;
    var lineDrawing:MovieClip = new MovieClip();
    this.addChild(lineDrawing);
    lineDrawing.graphics.lineStyle(1);
    lineDrawing.graphics.moveTo(_stage_center_x,_stage_center_y);///This is where we start drawing
    lineDrawing.graphics.lineTo(linetox, linetoy);
}
this.addEventListener(Event.ENTER_FRAME, enterframe);

很明显，这会将行的目的端移动得越来越低，只是想让它在屏幕上画画（就像时钟一样）

var center:Point = new Point(stage.stageWidth/2, stage.stageHeight/2);
var radius:Number = 200;
this.graphics.lineStyle(1, 0x000000, 1);

addEventListener(Event.ENTER_FRAME, drawCirc);

var _x:Number;
var _y:Number;
var _angle = -180;
var _rads = 0;
var rad_conversion:Number = Math.PI / 180;

function drawCirc($evt:Event) {
    _rads = _angle * rad_conversion;
    _x = radius * Math.cos(_rads) + center.x;
    _y = radius * Math.sin(_rads) + center.y;
    if (_angle == -180) {
        this.graphics.moveTo(_x, _y);
    } else {
        this.graphics.lineTo(_x, _y);
    }
    _angle ++;
    if (_angle >= 181) {
        removeEventListener(Event.ENTER_FRAME, drawCirc);
    }
}