I am trying to write a ray tracer to render boxes (cubes) that are arbitrarily rotated, i.e. not necessarily axis aligned. While I am reasonably comfortable ray tracing an axis-aligned cube (AABB), I don't know how to handle non-axis aligned objects. The geometry becomes quite difficult. I've looked through a textbook (*Ray Tracing from the Ground Up*) but couldn't find an answer.

How should I do it? Detailed suggestions would be greatly appreciated.