[izym]

Scratchapixel has a lesson on it [1] which takes the same approach.

[1]: https://www.scratchapixel.com/lessons/3d-basic-rendering/ray...

[mijoharas]

Of course, because we have the plane fixed at 1 unit in front of the camera, instead of moving that distance we have an adjusting factor that we multiple the co-ordinates by to change our field of view.

Thanks, I looked at scratchapixel but only found the stuff about how pinhole cameras work.