Undo changes made on terrain's splatmap

Questions & Answers
1

Hello,

I have a script that changes automatically the splatmap of a terrain.
I would like to be able to undo the changes made by this script through the Unity undo system.

Here is one of the code I’ve tried:

Undo.RegisterUndo(myTerrain.terrainData, "Automatic Paint - " + myTerrain.name);
ChangeMySplatMapData(myTerrain);

Does anyone know how to make it work?
(I really would like to avoid Undo.RegisterSceneUndo because my scene is really heavy)

Thanks :wink:

3

I ran into a similar issue with trying to record undo on my terrain’s TerrainData before modifying the heights. For my issue, I found that the Undo.RegisterCompleteObjectUndo function worked, so maybe try that?

2

Still looking for an answer on this one. Registering the terrain data should work since the splat map, like the height map, is part of the terrain data; but it doesn’t. Has to be a bug.

In the meantime, I guess you have to just implement your own solution. Save the splat map before changing it and create a button that reloads the saved map when you press it.

4

You can fix : Unity Terrain System, Brush Can't Undo Solution - YouTube

5

Recently ran across this as well. Was making an editor script that alters the height, splatmaps, and holes of a terrain and wanted undo functionality.

In Unity 2021.3 I had to register the terrainData.alphamapTextures. Here’s what I did before any operations on the terrain…

Undo.IncrementCurrentGroup();
Undo.RegisterCompleteObjectUndo(terrain.terrainData, "Modify Terrain");
Undo.RegisterCompleteObjectUndo(terrain.terrainData.alphamapTextures, "Modify Terrain");

Unity documentation also mentions this currently under:

“alphamapTextures: Alpha map textures used by the Terrain. Used by Terrain Inspector for undo.”