The current zoom implementation adds a certain amount to the fov on each scroll wheel event. While this works quite well for when you're at a mid zoom-range, when you zoom far in, the zoom moves too fast and when outside, it's too slow.

A better implementation is to instead multiply the current fov by some multiple (say 1.1*) and the zoom is a lot more controlled and smoother.

I made a demonstration to show the difference below in my own program:

Using a multiple:

I mentioned this in #88.