So, I'm trying to figure out how to do water. Right now, I am doing water the "brain dead" way; any tile below a certain height is water, and water is created as a simple hexagonal plane with a partially transparent blue material applied. It works okay, but the ultimate end goal is to have water play a more involved role in the landscape. I'd like to have rivers, waterfalls, etc... and that means that I need to rethink how I do it. I'm trying to come up with ideas for the geometry of water.

Here is a shot of how the current water system might look if I use it unmodified for multi-level water:

Clearly, I need some sort of geometry to tie the pieces together. My first thought is to create a sort of "skirt" piece that is attached to the side of a water hex if that water hex has neighbors whose water height is lower than its own. Might end up looking something like this:

The issue with that, of course, is that I have to oversize the skirts to avoid Z-fighting with the underlying ground hex, and that means that skirt pieces overlap with adjacent skirt pieces on different hexes and with the water hex of the lower water levels. In combination with the alpha-blending, this creates bands or regions of darker color where two pieces of water blend together. I could use waterfall particle systems to help obscure this overlap, I think. Alternatively, I could use a solid material instead of a partially transparent one:

I dont like the look of it, though. Large areas of flat water look terrible. Granted, there will need to be improvements to the actual water material to make it look better regardless of how I handle the geometry, but for now I'm sorta stuck on how best to do this. I do have some ideas as to how I could perform the geometry stitching of the skirts to minimize overlap, but it'll take the creation of special pieces, and some special-case code. Not too difficult, I suppose, but still seems kinda messy.