If you dont need it at runtime, then your best bet is to pull slope maps to convert into splat maps from passing your heightmaps into a GIS program.
Basically, you create a function to paint slope values of each pixel within a certain range from black to white, and you have yourself the file(s) to apply as the paint layer for whatever layer.
Its the same idea of how Auto Materials work, except you aren’t doing math at runtime so its way more performant, while also providing better to similar results.
Since modifying the landscape will not change the paint at runtime, you could also just create a runtime auto material to use for testing purposes, out of which you extract the slope ranges needed to extract the files to be used later on…
Ps: the idea of making a runtime editor plugin for this is very interesting and all, but I for one wouldn’t want to build anything onto something that in its current state shouldn’t exist and should not have existed past 10 years ago.
IF they ever actually fix how the landscapes works, then maybe there will be someone picking this up.
Until then, even if they did create a plugin, people using it would be limited to amateurs and indy devs…
Sincerly, both categories are way better off working outside the engine and learning about how things really work, so they can move their projects to less disastrously flawed engines…