How to go about collision detection in a first person world?

Hello,

I’m trying to achieve a collision detection similar to this example: three.js/games_fps.html at efbfc67edc7f65cfcc61a389ffc5fd43ea702bc6 · mrdoob/three.js · GitHub except that I want the player collision to be an AABB Box. Can I use the Box3 for the player and make it collide with the world? Or do I need to use Raycasters on the player for it to collide because the world might have complex terrain (like ramps, rocks, cliffs)?

Thanks in advance!