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[Emma Rivera]

Great topic, and honestly one that gets glossed over a lot in the general gaming crowd. At the core, hardware BVH traversal lives or dies on the slab test. When a ray (origin O, direction D) hits an AABB, you compute t0 = (min_i - O_i) / D_i and t1 = (max_i - O_i) / D_i for each axis, then swap them if D_i is negative so you end up with t_enter = max(t0, t1) and t_exit = min(t0, t1) across all three axes. If t_enter > t_exit on any axis, the ray misses the box entirely. That’s the entire cost center of a traversal step—three divisions per node. The clever bit on modern hardware is that you can invert the direction once up front (inv_D = 1/D) and reuse it, turning those divisions into multiplies. Combine that with the early-out on t_enter > t_current_best and you prune an enormous fraction of the tree before you ever touch a triangle.

The part people underappreciate is that traversal efficiency is really a build-time problem. A badly built BVH will murder your RT performance no matter how good your shader is. SAH (Surface Area Heuristic) splitting is the standard because it minimizes the expected traversal cost by weighting split probability against the surface area of child

"Nintendo 64 with UltraHDMI mod + EverDrive 64 X7 setup."

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