目前为止的例子都是使用缺省形状拣选对象：可以假想是一根从观察者眼睛的位置经过鼠标点至无穷远处的射线。
So far the examples have picked objects using the default shape: an imaginary ray going from the viewer's eye position through the mouse pointer into infinity.
各种形状都既可以行进到极远处(射线)或停止在固定的距离上(分段)，你也可以基于一个边界对象做拣选。
Each of these shapes can either go on forever (a ray) or stop after a fixed distance (a segment), you can also pick based on a Bounds object.
这一不寻常的X射线和光发射的组合使它成为一个显著的对象。
The combination of this unusual X-ray and optical emission makes this a remarkable object.
应用推荐