幕上光标选择到对象的深度值和其他显示对象的深度值。

键盘、鼠标、数字化仪等交互设备均为二维的，不能适应三维交互工作的需要。

-Cursor to select an object on the screen to the depth values and depth values of other display objects. Keyboard, mouse, digitizer devices such interactions are two-dimensional, three-dimensional interactions can not meet the work requirements.