These are some visualizations I made to help understand the intersection of a ray with an axis aligned bounding box — the slab method.

TL;DR:

2D demo here

3D demo here

Algorithm:

Resources:

• Exhaustive list for ray-object intersections collected by the guys from real time rendering:
• Peter Shirley (& Andrew Kensler at Pixar)
• old code from “Graphics Gems”