It's been feasible for about a decade on modest hardware, just not at super-high resolutions and framerates that most people expect from modern GPUs. (Outbound

It's been feasible for about a decade on modest hardware, just not at super-high resolutions and framerates that most people expect from modern GPUs. (Outbound was a sort of a technology demo/student project game that I remember being sluggish but playable on a Core 2 Duo.) Also, plain raytracing can look kind of bland. Most global illumination algorithms are based on ray tracing, but require tracing a very large number of rays. So, really the question is more whether we can get to real-time path tracing, which is a harder problem. Another problem is tooling. Game developers know how to get good performance on GPUs, but ray-tracers have completely different performance characteristics. Re-building a bounding volume hierarchy is, in general, O(NlogN), so you have to be careful about partitioning your scene into things that move/deform and things that don't and only rebuild the parts of the BVH that need updating.