求助~如題~跪求大神~

It depends on which mode you are running. It sounds like that its either the ray is totally internal reflected in sequential mode or in non-sequential mode that the ray aiming at a direction that there are no objects it will intercept with. P I"KY@>H  
~Re4
zU  
The info you provided was limited so my reply is purely a speculation.

我也想知道是怎么回事

我也想知道哦