For perspective correct texture mapping quake did the distance divide every 8 pixels on the FPU, and the affine texture mapping on the integer side of the CPU i

For perspective correct texture mapping quake did the distance divide every 8 pixels on the FPU, and the affine texture mapping on the integer side of the CPU in between (you can actually see a little bit of “bending”, if you stand right next to a wall surface in low res like 320x200). Since the FPU could work in parallel with the integer instructions on the pentium, this was almost as fast as just doing affine texture mapping. This worked even on the basic Pentium. It was likely also the reason Quake was a unplayable on the 486 and Cyrix 586.