fix: gameobject-find can't locate objects in DontDestroyOnLoad or non-active scenes (#826) - #858
Open
gfranklin1 wants to merge 6 commits into
Open
Conversation
…ve scenes (IvanMurzak#826) FindRootGameObjects() only searched EditorSceneManager.GetActiveScene(), so gameobject-find silently missed objects in additively-loaded but non-active scenes, and always missed DontDestroyOnLoad (which isn't part of SceneManager's scene list at all). Now unions roots from every opened scene (SceneUtils.GetAllOpenedScenes), plus a Play-Mode-only scan for DontDestroyOnLoad root objects. Mirrored across both the Unity 6000.5+ and pre-6.5 Editor variants of GameObjectUtils, since only the pre-6.5 file actually compiles on this project's Unity version.
Contributor
There was a problem hiding this comment.
Pull request overview
This PR fixes gameobject-find missing GameObjects that live in additively-loaded (but non-active) scenes and in the DontDestroyOnLoad scene while in Play Mode, by widening the root search scope in the Editor-only GameObjectUtils.FindRootGameObjects() implementations.
Changes:
- Update Editor
FindRootGameObjects()to union roots from all opened scenes (not just the active scene) and additionally includeDontDestroyOnLoadroots while playing. - Add an EditMode test covering loaded-but-not-active additive scenes.
- Add a PlayMode test covering objects moved into
DontDestroyOnLoad.
Reviewed changes
Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| Unity-MCP-Plugin/Packages/com.ivanmurzak.unity.mcp/Runtime/Utils/GameObjectUtils.Editor.cs | Expands Editor root-object enumeration to include all opened scenes + DontDestroyOnLoad roots in Play Mode (Unity 6000.5+ branch). |
| Unity-MCP-Plugin/Packages/com.ivanmurzak.unity.mcp/Runtime/Utils/GameObjectUtils.Editor.pre-Unity.6.5.cs | Same root-object enumeration expansion for pre-6.5 Editor branch (Unity 2022/2023 compatible). |
| Unity-MCP-Plugin/Packages/com.ivanmurzak.unity.mcp/Tests/Editor/TestGameObjectUtils.cs | Adds EditMode regression test for non-active additive scene lookup. |
| Unity-MCP-Plugin/Packages/com.ivanmurzak.unity.mcp/Tests/Runtime/TestGameObjectUtils.DontDestroyOnLoad.cs | Adds PlayMode regression test for DontDestroyOnLoad lookup. |
| Unity-MCP-Plugin/Packages/com.ivanmurzak.unity.mcp/Tests/Runtime/TestGameObjectUtils.DontDestroyOnLoad.cs.meta | Adds Unity meta for the new runtime test asset. |
Files not reviewed (1)
- Unity-MCP-Plugin/Packages/com.ivanmurzak.unity.mcp/Tests/Runtime/TestGameObjectUtils.DontDestroyOnLoad.cs.meta: Generated file
Assert EditorSceneManager.SaveScene succeeded instead of ignoring its return value, and swap in a fresh untitled scene before deleting the temp scene asset so the active scene never points at a deleted file.
Author
|
Pushed a follow-up commit addressing both Copilot review comments on the additive-scene test's cleanup logic. |
Contributor
There was a problem hiding this comment.
Pull request overview
Copilot reviewed 4 out of 5 changed files in this pull request and generated 3 comments.
Files not reviewed (1)
- Unity-MCP-Plugin/Packages/com.ivanmurzak.unity.mcp/Tests/Runtime/TestGameObjectUtils.DontDestroyOnLoad.cs.meta: Generated file
FindRootGameObjects(scene: null) is Editor-only by design (see GameObjectUtils.Runtime*.cs); a standalone Player build of this test assembly always gets null there, unrelated to whether the DDOL fix itself works. CI runs a standalone PlayMode job against this package (Unity-Tests/*/Packages/manifest.json references it via testables), so without this gate the test would fail there for the wrong reason.
IvanMurzak
requested changes
Jul 6, 2026
IvanMurzak flagged FindObjectsByType/FindObjectsOfType as a
performance problem on heavy scenes, since it was scanning every
GameObject on every no-scene find call while playing. Copilot's
suggested alternative (SceneManager.GetSceneByName("DontDestroyOnLoad"))
was tried and confirmed not to work: that scene was never registered
in SceneManager's scene list to begin with, which is the entire reason
FindRootGameObjects() needed a workaround in the first place.
Instead, GetDontDestroyOnLoadScene() probes for the DDOL Scene handle
once via a throwaway GameObject, caches it, and self-heals via
IsValid() if it's ever invalidated (e.g. after a domain-reload-free
Play Mode restart). Every subsequent call is just a cheap
scene.GetRootGameObjects() instead of a world scan.
Contributor
There was a problem hiding this comment.
Pull request overview
Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.
Files not reviewed (1)
- Unity-MCP-Plugin/Packages/com.ivanmurzak.unity.mcp/Tests/Runtime/TestGameObjectUtils.DontDestroyOnLoad.cs.meta: Generated file
Comment on lines
+67
to
+70
| var probe = new UnityEngine.GameObject("~DDOLSceneProbe") { hideFlags = UnityEngine.HideFlags.HideAndDontSave }; | ||
| UnityEngine.Object.DontDestroyOnLoad(probe); | ||
| var scene = probe.scene; | ||
| UnityEngine.Object.DestroyImmediate(probe); |
Comment on lines
+68
to
+71
| var probe = new GameObject("~DDOLSceneProbe") { hideFlags = HideFlags.HideAndDontSave }; | ||
| Object.DontDestroyOnLoad(probe); | ||
| var scene = probe.scene; | ||
| Object.DestroyImmediate(probe); |
Object.Destroy(probe) is deferred to end-of-frame, so the very next GetRootGameObjects() call on the same frame could still see the probe as a root. Filter it out by reference instead of relying on DestroyImmediate's synchronous removal, since DestroyImmediate is discouraged in Play Mode and GetDontDestroyOnLoadScene() only ever runs while Application.isPlaying is true.
Author
|
Side note about Copilot's latest critiques; |
Author
|
Hey @IvanMurzak, following up on this whenever you get a chance. I addressed the review feedback ( |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fixes #826.
Root cause
GameObjectUtils.FindRootGameObjects()(called bygameobject-findwhen no explicit scene is given) only searchedEditorSceneManager.GetActiveScene().GetRootGameObjects(). Two consequences:DontDestroyOnLoadwere always missed - that scene isn't part ofSceneManager's enumerable scene list at all, and only exists once the Editor/Player is in Play Mode.Fix
Two-part change to
FindRootGameObjects(), mirrored across both Editor-gated variants ofGameObjectUtils(GameObjectUtils.Editor.csfor Unity 6000.5+,GameObjectUtils.Editor.pre-Unity.6.5.csfor pre-6.5 - only the latter actually compiles on Unity 2022.3, which is why both needed the identical fix):SceneUtils.GetAllOpenedScenes(), not just the active one.Application.isPlaying, additionally scan forDontDestroyOnLoadroot objects viaFindObjectsByType<GameObject>(FindObjectsInactive.Include, FindObjectsSortMode.None), filtered toparent == null && scene.name == "DontDestroyOnLoad".No dedupe is needed: every GameObject belongs to exactly one scene, and DontDestroyOnLoad is disjoint from the
SceneManager-enumerable set, so the two result sets can't overlap.Prefab-stage handling and the explicit-
scene-argument path are untouched.GameObjectData's result shape is untouched - the fix is entirely below that layer.Why not
GameObject.Find(name)GameObject.Findonly searches active GameObjects in loaded scenes and (in most Unity versions) still missesDontDestroyOnLoadroot queries the same way - it wouldn't fix the actual bug, and it silently skips inactive objects, which would be a regression against the current recursive/inactive-aware search.Testing
Verified with a real red→green cycle, not just written-and-assumed:
Tests/Editor/TestGameObjectUtils.cs::FindByName_AdditiveScene_ObjectIsFound- creates an additive, non-active EditMode scene; confirmed fails on unfixed code, passes with the fix.Tests/Runtime/TestGameObjectUtils.DontDestroyOnLoad.cs::FindByName_DontDestroyOnLoad_ObjectIsFound(genuine PlayMode test) - confirmed fails on unfixed code, passes with the fix.Out of scope
A related bug in
GameObject.Hierarchy.cs:68was noticed while investigating but is intentionally not touched here - flagging for maintainer input on whether it should be a separate PR.Note: #836 is an existing open PR attempting the same issue. This PR is scoped narrower (DDOL + additive-scene fix only, no unrelated log changes) and fixes both halves of #826 - #836 only addresses the DDOL case, not the non-active-scene case.