///<summary>
///返回_3dPos 到 屏幕上方的NGUI位置
/// </summary>
/// <param name="_3dPos">必須在3d相機的視野範圍內,否則轉換錯誤</param>
/// <param name="_3d"></param>
/// <param name="_2d"></param>
/// <param name="uiWidget"></param>
/// <returns></returns>
public static Vector3 TopNgui(Vector3 _3dPos)
{
Vector3 pos = _3dCamera.WorldToViewportPoint(_3dPos);//頭頂座標轉 視口座標 ,得到頭頂座標在視口座標的位置,
Vector3 ViewportScreenTop = new Vector3(pos.x, 1f); //然後就可以計算得出 人物對應屏幕的最上方座標, 屏幕最上方點視口座標 new Vector3(pos.x, 1f)
_uiLabel.transform.position = _2dCamera.ViewportToWorldPoint(ViewportScreenTop); // 然後把 屏幕最上方 座標轉成 世界座標
pos = _uiLabel.transform.localPosition;
pos.x = Mathf.FloorToInt(pos.x);
pos.y = Mathf.FloorToInt(pos.y);
pos.z = 0f;
_uiLabel.transform.localPosition = pos;
return pos;
}