Horizontal spread dependant on pitch

[StroggVorbis]

I noticed (in 3DGE too, and probably in other source ports as well) that the higher or lower you aim, the less horizontal spread fired hitscans and projectiles have. Firing while looking exactly 90° up or down will have no vertical spread at all. I've seen this with vanilla weapons and weapon mods too. Is this intended behaviour or is there a flag to change this?

[Graf Zahl]

This is how Doom always worked. The spread is calculated on the 2D plane so with higher pitch the actual xy-part of the vector is shorter, so there's less spread.

[StroggVorbis]

If there isn't already, would it make sense to implement this as a flag or compatibility option?

[Graf Zahl]

It's not that easy, because the entire hitscan calculations are done in 2D, with the z-component as an afterthought, just like pretty much everything else in Doom.