TileMap Terrain: preview tiles are wrong relative to the tiles that actually get placed

[amonroejj]

Godot version

4.0.beta10

System information

Windows 10, NVIDIA GeForce GTX 1060 516.94

Issue description

Using a Kenney tilemap, I tried to make a TileMap terrain set of single-tile-width river tiles (i.e. no lakes). The terrain is made up of one corner and one straight. That corner and straight have alternatives to cover the four cardinal directions.

When placing these into the TileMap, the preview for the tiles are incorrect (the in-game tiles are correct.) For example, preview tile 1 is incorrectly shown as a lake corner but the in-game tile is correctly shown as a west-to-north river piece. Preview tile 4 is incorrectly shown as a lake south shore but the in-game tile is correctly shown as a north-to-east river piece.

Steps to reproduce

Try the included repro project.

Minimal reproduction project

terrain_bad_preview.zip

[groud]

This might be expected. If two terrains share the exact same terrain bit setup, the algorithm will randomly choose one of the terrains with that setup. As a consequence, the preview might not always fit the painted tile.

[amonroejj]

@groud This misses the point of the bug report in that I never chose lake pieces as part of the terrain, so they should never be part of the preview.

[groud]

Ah right, I have checked the reproduction project and it is indeed a bug.

[amonroejj]

This defect is still present in 4.4.1.

[kleonc]

Seems fixed by #109584, since v4.5.beta6.official [d5ad055].