It worked, thanks! :) I did hit snags where it didn't seem like the masking mesh was working, but that got fixed once I cleared the old material I had on it. Since I already had stuff connected to opacity in the water material, I found I had to add that input with itself and then combine it with the custom depth nodes with…
I set up this diorama thing in Unreal. Nice and dandy, except the water material clips inside the fish's mouth. Not good. So I poked around the internet, and it seems like the solution to this problem involves custom depth. Most resources point to this guide, but it seems like that's for stuff like Assassin's Creed eagle…