I ve generated river mesh and good news is it works. But honestly in way how it is implemented it is not usable at all. To be really useful, you need to generate it as extruded spline with UV mapping in direction of water flow (planar mapping is not usable for this case). It can be (should be) little bit wider than river bed, so no need to copy river shape precisely up to pixel. It should look like this. Each segment is usually 0-1 UV range and should have smiliar length:
That’s useful feedback, thank you. While building the river tool, it was not always clear what form everyone needs the data in, as the use cases are quite disparate. Some people just need to color the terrain, others need full geometry, and everything in between.
Exporting river-path UVs to go with the mesh was planned but cut due to time constraints. However it is definitely extremely useful both within WM and further down the content pipeline. I’m hoping to be able to address this in the next feature-focused release.
In case you need help with specifications and or testing, just write me. I know exacly what game engine needs (it is more or less same for each), so I can help you with that. Generating of water meshes by hand is really pain in the ass even if game engine supports that. For bigger terrains (kms and kms of rivers by hand is not much possible), so this could be really outstanding feature, nobody else have.
On this video you can see, how is such mesh is constructed and how it must be UV mapped (river is identical case). Wihout such UV mapping you cant make water flow: