I meant catching on in terms of the algorithms they can use. GPUs can finally apply the same features as offline rendering for realtime use, albeit in limited form."Just catching on" means it could have been done long before but people missed the trick, and are only just now 'catching on'. GPUs aren't 'just catching on'. They are evolving to support more features now that that's possible, primarily because lithography allows large enough processors, and partly because of the evolution of GPGPU to compute as driven by software developers. Everyone knew what RT was and what it offered, but it wasn't possible to do anything about it until now.