Transparent pixels overwrite everything in the tile below

[TomTheBBq]

I have this tile of a bridge with some transparent pixels on the side, let’s say I want to apply it to the middle of some other water tilesets

The result would be the transparent pixels overwriting everything on the previous tiles

Is it possible to avoid this without creating new tiles in the tilemap? Basically making the transparent pixels ignore the tile below, so everything stacks up. I’ve had this kind of problems with trees too, and the only solution I’ve found is replacing the transparent pixels with the same green the as the grass but I can’t apply this to every type of tiles, like the bridges from before. Sorry if this is a stupid question but I’d like to understand more about tilemap layers and this behaviour

[eishiya]

A tile layer can only contain one tile in each cell. Think of tile layers as containing not the tile pixel data, but just a tile ID, telling it which tile’s data to display in each cell.
If you want some tiles to overlap others, you’ll need to use multiple tile layers.

Unfortunately, current Aseprite has a separate tileset per layer, so you’ll have to copy/move the overlapping tiles to the new layer. AFAIK it’s planned to be able to reuse tilesets across layers.