[pcwalton]

Raytracing can absolutely be done on GPU even without RTX-style hardware; there are tons of implementations of it in the literature. Last I read the research, the best approaches dynamically bundle up rays hitting the same or nearby objects to squeeze coherency out of the GPU.

As far as I can tell, the biggest problem is simply that GPU raytracing requires a completely different software architecture. Giant boil-the-ocean rewrites that require not only new software but also new hardware are very difficult to justify, especially in a mature industry dominated by (relatively) short-term film production schedules. There are other technical issues too, such as VRAM limits.

[selectodude]

>Giant boil-the-ocean rewrites that require not only new software but also new hardware are very difficult to justify, especially in a mature industry dominated by (relatively) short-term film production schedules.

Anybody want to take my PhysX card off my hands? :)