>>5887346>But can't you make the iris and pupil any size and still have it work?That's a good question. I tend to lean towards no, but it's not without at least a little flexibility. In the case of Sonic, there's a lot of sclera (the "white" of the eye) exposed in his normal expressions, but there's still a LOT of room for him to move his eyelids around.
In my personal experience, the most important thing is the relationship of the iris itself and the eyelid, whereas the pupil size doesn't tend to matter. I've drawn images with tiny pupils, I've drawn images with massive pupils. If I see something's off with the eyes, usually expanding or shrinking the irises fixes it.
I also think that both eyelids need to be taken into account. Say you have a character at an angle. Depending on the shape of the eyes, one side will have more whitepace between the eyelid and the iris than the other side. I think when we're viewing faces, both sides are taken into account, with your brain interpreting the emotion based on the closer distance.
And for my final thought, I would say you can more or less freely shrink the horizontal axis. Many eyes use oval irises, and they're pretty much exclusively vertically-biased.
It goes without saying that none of these are concrete rules; they're just my experiences and observations. The best way to find out what works is to experiment and play around with expressions.
