alt Hacker NewsIt means almost an order of magnitude less divisions (and additional calculations as well).
Quake had to do this because it would have been too much especially for a low-end Pentium when it was released in 1996. Yes it is not even noticeable, especially at low res.
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badsectoracula • 10/02/2024
Depends on the textures used. High contrast textures with vertical lines (e.g. dark wood on bright wall) would make the distortion very visible even at 320x200. However most of the game's textures are not like that.
There are some user made maps however where this can be seen (e.g. i remember playing a map which was supposed to be inside a fantasy town and it used a bunch of wood-on-wall textures that made the distortion apparent).
Abrash did this in Quake because those divides are _Free_ when intervened with other code. Pentium FPU is pipelined, you can push FDIV, then FXCH to another data and do something else for a while instead of waiting for the result. The price is hand tuned assembly code that works fast only on Intel FPU in 1996. AMD caught up in 1998-99 finally implementing pipelined FDIV and 0 cycle FXCH.
https://www.phatcode.net/res/224/files/html/ch63/63-02.html