[royjacobs]

Quake perspective corrects only every 16 pixels and does linear interpolation in between. This is because the correction requires an expensive FPU divide.

While the FPU is busy doing that, the CPU can do the linear interpolation. Once the CPU is done with the 16 pixels, the FPU has also completed the divide and the CPU can do the next 16 pixels, and so on.

Looks pretty decent but is not 100% accurate.