I was testing with the Melbourne tileset in the examples project (which is entirely opaque) and giving it a translucent material. I didn’t see any obvious artifacts, which I took to mean it was doing correct depth testing. But when I looked closer just now, I saw some. I think it wasn’t obvious at first because Melbourne has very small tiles.
So, digging into this a bit more (but only a little), I think the proper solution is to separate translucent primitives from opaque ones, and use the appropriate type of material for each. That’s not too hard, but will contribute to the shader explosion I mentioned we’re trying to avoid. Perhaps there’s a more clever solution I’m not aware of.
In any case, I’ve updated the issue to mention this problem and link to this thread:
I don’t think we’re going to be able to fix this right away, but would welcome a pull request if you have an idea how to implement it!