Shameless self promotion, but if you're interested in how collision detection was done in 3D (in Quake) I made a video on the topic here:

https://www.youtube.com/watch?v=wLHXn8IlAiA

The technique can detect the intersection point of a (fixed size, axially aligned) moving bounding box and a hull defined as a BSP tree. In this sense it is rather limited compared to newer methods but it works rather well and the implementation is pretty robust, and fast enough for the primitive hardware of the day.