世界坐标转到UGUI坐标

尝试了几个版本都不对，下面俩是正确的。

public static Vector3 WorldToUI(Camera camera,Vector3 pos){
		CanvasScaler scaler = GameObject.Find("UIRoot").GetComponent();

		float resolutionX = scaler.referenceResolution.x;
		float resolutionY = scaler.referenceResolution.y;

		Vector3 viewportPos = camera.WorldToViewportPoint(pos);

		Vector3 uiPos = new Vector3(viewportPos.x * resolutionX - resolutionX * 0.5f,
			viewportPos.y * resolutionY - resolutionY * 0.5f,0);

		return uiPos;
}
public static Vector2 WorldToUIPoint(Transform worldGo)
    {
        Vector2 pos;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(canvas.transform as RectTransform,
            gameCamera.WorldToScreenPoint(worldGo.transform.position), canvas.worldCamera, out pos);
        RectTransform rect = transform.transform as RectTransform;
        return pos;
}