Autotile on multiple layers

[formal ivy]

I'm playing around with this tile set (https://cainos.itch.io/pixel-art-top-down-basic). The environments are made with multiple layers: one for the grass, one for the shadows, one for the buildings. I have been looking at auto-tile documentation, api, and some videos. It does provide limited result. Can you help me to confirm my understanding?

First it looks like painting some terrain can only update the tiles of a single TileMapLayer (the current one). That cannot auto-paint shadows corresponding to a building or stairs in another layer, isn't it?

Then it can only pick a tile based on adjacent tiles. On that tileset the walls are composed of 2 tiles vertically, and I would love to be able to just pain a building and have the wall assembled. there are also situations where I would need to lookup at 2 tiles on the side to pick the right border. That is not possible isn't it?

I'm willing to code that logic, but I can't see any hook to react on terrain edition in a @tool. Is there a way to script my own tile assistant?

@gaunt fox I noticed better terrain, categories might help with my second point. Is it able to operate on multiple layers?

[formal ivy]

I'm playing with better terrain which is well polished. I have hard time making it pick the right tile. I suppose it count how much terrain constraint are satisfied. I seems that sometime I would like to express the difference between "either terrain or not" and "no terrain". I noticed that the video used an "inside terrain". Maybe that is what I need.

[gaunt fox]

Hi, Better Terrain doesn't do anything across layers.

for tilesets like this, it is usually helpful to make the taller parts into 1x2 sized tiles and work from there