Motion blur rendering on GPU

[Zhenyi-Liu]

Hi Matt,

I noticed that currently the motion blur is not yet supported on GPU, I wonder is there a plan on adding that or that will be a reader's homework? :)

Thanks,
Zhenyi

[mmp]

It's a TODO (issue #7...) It hasn't been high priority since the book doesn't discuss use of the OptiX APIs, so implementing that is not holding up finishing up the book. PRs welcome. :-)