Realtime raytracing didn’t exist until recently but people have been dabbling with doing it at much slower speeds, and sequencing the resulting frames, for a long time.
[0]: http://www.realtimerendering.com/resources/RTNews/demos/over...
Realtime raytracing didn’t exist until recently but people have been dabbling with doing it at much slower speeds, and sequencing the resulting frames, for a long time.