PB Meshes don't play nicely with Improved Prefab workflow?

Is it necessary to enable the "experimental" Meshes as Assets feature in order for PB objects to behave cleanly in prefabs under 2018.3? By "cleanly", I mean that currently every prefab instance I have that contains a PB object considers itself to have overrides, because the Mesh is different. For example:



No matter how many times I Apply or Revert these overrides, they remain overrides. If I go into Prefab mode, the actual prefab has a different Pb_mesh-xxxx ID.

I'm hesitant to enabled an "Experimental" PB feature though, especially as I don't know anything about it, or whether there's a better way for PB objects not to act like overrides in prefabs.

 

Thanks. Meaning that in some future release of Unity or ProBuilder, Unity will stop telling me that my prefab instance containing PB meshes has overrides due to the PB mesh?

 

@gabrielw_unity Can you elaborate on what's happening here? We are seeing issues handling prefabs and prefab instances using Unity 2018.3.5 and ProBuilder 4.04.

It appears that ProBuilder is aggressively regenerating meshes across instances of prefabs, even if they should share the same mesh as the prefab asset. The repro is very simple: create a new PB cube mesh and make it a prefab. Then drag that prefab into a scene. Notice that the mesh on the instance is different than the mesh on the asset, and the instance has been flagged as having an override

This happens whether or not Meshes are Assets is checked. This is odd to me since, digging through the the ProBuilder package source, it appears that Meshes are Assets should be causing ProBuilder to attempt to cache and re-use the same mesh across instances and assets.

This is causing one major issue for us currently, and I'm worried it may be less obviously causing several more.

The obviously apparent issue is that loading a scene containing large ProBuilder meshes takes freaking forever, spending multiple minutes in a call to Prefabs.MergePrefabs() from LoadLevelAsync() -- my guess is that all the meshes are being regenerated during deserialization, causing extremely long hangs.

The other issues I'm concerned about are purely hypothetical, but I'm guessing that this could be bloating our application's memory budgets at runtime. If we have 100 instances of the same ProBuilder prefab, will we be generating 100 identical meshes to store in memory?


If you're able to shine any light on what is happening here and what possible workarounds are, I'd be very grateful. Right now I don't know if we're running into a bug, or if we're just misunderstanding the way in which ProBuilder is intended to be used. The repro steps I mention feel extremely broken to me, but it's possible I'm just confused about what is happening under the hood.

 

One of my coworkers just build a min repro project that confirms that the issue still occurs on 2018.3.10. In the min repro project, it's really apparently that we're just generated new meshes all over the place -- every time you drag the Cube prefab into a scene, you can see a new mesh asset generated on-disk and added to the ProBuilderMeshCache folder.

 

"Meshes are Assets" works pretty poorly for us. It does the same 'generate meshes all the dang time' behavior, with the added fun of writing a new asset to disk and incurring the file I/O costs.

We've ended up writing our own code to build out the generated mesh to our own asset cache and delete the ProBuilderMesh script entirely when we're not actively editing the meshes. It's a little gross, but it means our scenes load in 5-10 seconds instead of the 10 minutes it was taking before.

 

Correct. The simple repro was:

- Make a Probuilder cube
- Make it a prefab (drag it into the project view)
- Drag that prefab into the scene to create an instance
- Look at the instance in the inspector and note that it has generated a new mesh asset and overridden the prefab mesh references

Looking at Probuilder's code, it looks like it attempts to reuse the same mesh across prefab assets and instances if Meshes are Assets is enabled, but for some reason that was not working properly for us.

 

Thanks for looking into it!

 

Hi everybody !

Is this issue resolved ? Because i have the same problem here. :/

@gabrielw_unity

 

Is there an ETA on fixing the original problem mentioned in this thread--namely prefabs always thinking PB objects have overrides? It's making it hard to maintain prefabs and whether they're up to date.

 

This is good to hear. I'll check out 4.3.0-preview.2 when I see it.

 

Have you guys not published an update to the Changelog for this release? Or is there something going on with docs.unity3d.com that isn't showing the latest changelogs? The site is still only showing changelog info through
4.3.0-preview.1.

I can see the changelog changes on github. I'm just curious why it's not in the docs site. (https://github.com/Unity-Technologies/com.unity.probuilder/blob/rc-4.3.0-preview.2/CHANGELOG.md)

 

So I tried 4.3.0-preview2 this morning but it doesn't appear to have addressed the prefab override issue yet. Here's what I'm seeing for overrides. Going inside the prefab and saving it doesn't help, as well as applying all changes or reverting all changes.

 

Also it looks like w/ 4.3pr2 when I make a windows build all my probuilder geometry disappears. Possibly related to the mesh filter change?

 

Disabling "Script Stripping" ended up being my temp fix for the build issue.

Another issue I came across is mesh colliders stop working because they can no longer find a mesh on the probuilder object. I think this might be due to the probuilder update migration, since creating a new probuilder object has a proper mesh reference on the mesh collider.

EDIT: Submitted a bug report for the disappearing geo build issue: 1214103

 

This is still an issue with the Unity 2019.4.5 LTS build and ProBuilder 4.2.3. This bug is pretty annoying and it's disappointing it hasn't been fixed after years.

 

What do you mean "still" an issue? You've listed an older version of ProBuilder. Version 4.2.3 is still the latest "verified" version of PB, but as Karl mentioned above, this is fixed in PB 4.3. So you'll need to update ProBuilder if you want the fix for this.

 

4.2.3 is the latest version provided in Unity's official package manager.

 

You need to enable Preview packages. There are several newer versions than 4.2.3 in the package manager.

 

I have preview packages enabled, 4.2.3 is still the latest version I can grab in the 2019 LTS. My complaint is that such a common, editor-breaking bug should be fixed in an LTS version.

 

I'm on 2019.4.5 LTS. Just click see all versions:

It is fixed in an LTS version.

 

Hi all.

I'm currently on Unity 2020.1.9f1 Personal and using Probuilder 4.4.0. I'm still having the problem described in this thread, namely that PB Meshes keep being shown as overrides in all my prefab instances. Looking at the known issues of this version I see the following:

Known Issues

• Prefab Stage does not work properly when ProBuilderMesh contains overrides that append geometry.

Is there an ETA on when this will be fixed? Thanks in advance!

 

after 4 years we still have this issue on unity 2021.3.11 using Probuilder latest version 5.0.6.
as others mentioned above, prefabs always thinking PB objects have overrides. It's making it hard to maintain prefabs and whether they're up to date. making it hard to find actual overrides if we use some proBuilder objs in our prefab.
This is annoying and has hindered the speed of our work.

@kaarrrllll
@gabrielw_unity