How to know what makes scene dirty?

So, what the title says. Every time I start editor my main scene is marked dirty.
I tried to isolate all my editor code and double checked if there is any SetDirty or Undo methods which may cause it but unable to find the culprit yet.

I'll dig it up eventually but just wondering if there is some way to check what is marking scene dirty, some editor event accessable via reflection or something

 

Not yet. I think Unity knows about this specific issue developers have to deal with so maybe they implement something in the future.

Until then, the only thing is to scan the code base for calls to Undo, SetDirty, SerializedProperty, PrefabUtility and probably a few other API calls used in different utilities.

One thing to try, however, would be Undo.postProcessModifications. With this callback many of the changes in a scene become visible, but you would need to register to te callback before the change is made and of course it only catches calls registered via Undo.

A potentially good solution would be an event which is triggered by Unity whenever the scene is marked dirty. Tool developers could then walk the callstack to find the culprit.

 

For everyone stumbling over this thread, the callback exists now:

EditorSceneManager.sceneDirtied += SceneDirtied;

And with the three dots in the console, enabling full call stacks (thanks for the hint, Xarbrough) I was able to track it down to ProBuilder - which seems to optimise (and dirty) it's meshes on every performed Undo/Redo.

 

Oh my, that's super helpful, thanks!

 

This was able to help me track unknown scene dirty, where

Undo.postprocessModifications

cannot track.

Enable full stack trace here as above comment suggested:


The result will look like this. It was from my dumb "[ExecuteAlways]" script. Sigh...


For the sake of completeness, I will include my tracker script for non-coder to copy too. (Because I know you like to copy-paste, it is satisfying!)

• Copy and add this file into editor script folder. (like Assets/Scripts/Editor)
• Then from upper menu, select Tools->Wappen->Toggle scene change tracker

https://gist.github.com/wappenull/acfd388185c543bfe8fa98f6ab07f317