UGUI UI坐标转世界坐标

Vector3 ptScreen = RectTransformUtility.WorldToScreenPoint(UIManager.Instance.UICamera, m_IconGold.transform.position);
ptScreen.z = 0;//根据你需要的 相对于camera3D的Z值来设置该值

Vector3 ptWorld = Camera.main.ScreenToWorldPoint(ptScreen);

UIManager.Instance.UICamera是你Canvas上绑定的Render Camera