In virtual reality, the motion-to-photon time is very important. Oculus says it has to be less than 20ms. Maybe 10~15ms is better.
Some people try to introduce Frameless rendering technology into VR. I think it's good to reduce the latency. But I don't know how the display quality is. According to the paper: "Adaptive Frameless Rendering" and the video (https://www.youtube.com/watch?v=ycSpSSt-yVs), it seems not very good. But, in this paper "Construction and Evaluation of an Ultra Low Latency Frameless Renderer for VR""Construction and Evaluation of an Ultra Low Latency Frameless Renderer for VR", the authors used FPGA instead of GPU to render and used Frameless Rendering to reduce the latency to 1ms.
In my mind, FPGA is very hard to replace GPU in 3D rendering area. And, Frameless Rendering needs "racing the beam", it is also very hard to program.
What do you think? Is it realistic to use FPGA and frameless rendering?