What exactly will/won't break precombines?

[Aizekku]

Hello all, I've never asked for help on here before, but recently I started doing a bit of Fallout 4 modding and I've run into some confusing things. I've made a handful of Skyrim and Skyrim: Special Edition mods in the past (both published and private) and I'm very confortable using the Creation Kit, but I've never had to deal with things like "precombines" before.

 

Anyway, I'm working on a mod that makes a variety of changes to the way radiation works. The first half of the mod simply changes the amount of rads picked up from various sources - from environmental sources, from creatures, and from food and water. I know I'll have absolutely no issues with this. The part that concerns me, though, is the second half of the mod, which will add potentially hundreds of new radiation hazards to the Commonwealth worldspace. I will try to avoid touching anything else or adding new objects to any cells, and I plan to avoid settlements and frequently-modded areas, but I'm worried about breaking something by accident.

 

I'm slightly concerned about the potential effects that adding additional hazards and messing around with the worldspace might have on the mod's compatibility with other mods. If I was changing just a few cells, I wouldn't be worried, but I'm planning on changing possibly hundreds of locations all over the map. I also am not entirely confident about which types of changes WILL break precombines and which ones will NOT. My main questions are...

 

- Will adding hazards have any effect on this, or is it totally a non-issue, as I suspect?

- What about light sources, x-markers, or anything else that has a visible shape in the editor that doesn't appear as a physical object in the world? Will moving/adding these have any effect on optimizations?

- How can I tell whether or not I've accidentally broken an optimization, and how can I fix this if necessary?

- Will clutter and non-static objects be safe to move around, or should this also be avoided?

- If I move something accidentally, will deleting the changes in FO4Edit also restore any potentially-broken optimizations?

- Am I just being too cautious?

 

I've done a fair amount of research already, but there's still a lot I'm confused about, and apparently I'm not alone in that respect. So I thought I'd ask just to be on the safe side! Thanks to anyone who can answer these questions! :laugh:

Edited June 26, 2020 by Aizekku

[pra]

âPlacing objects is generally safe. It's deleting objects which can break precombines. And even then, it's only about statics, SCOLs and the Landscape. Maybe also projected decals, but I doubt it.
Statics which are linked to something are exempt, too. Like, in some settlements, a box on a shelf is linked to the shelf itself.
In that case, both the box and the shelf aren't part of precombines.

There is an edgecase: If you change anything within a cell, you create an override for that cell, with precombines as they were in the master files you were using.
That is, if your mod depends on Fallout4.esm only, and, let's say Nuka World has different precombines for that cell, you would potentially create a conflict with Nuka World.
Also, mods like Beantown Interiors. It has an optimized version which redoes precombines for A LOT of vanilla cells.

However, in your case, this won't be an issue, if your mod is simply loaded BEFORE BTI. Then, your placed objects show up, but their precombined changes apply.



Now to answer your questions:

- Will adding hazards have any effect on this, or is it totally a non-issue, as I suspect?

It is a non-issue

- What about light sources, x-markers, or anything else that has a visible shape in the editor that doesn't appear as a physical object in the world? Will moving/adding these have any effect on optimizations?

Same.

- How can I tell whether or not I've accidentally broken an optimization, and how can I fix this if necessary?

Most reliable way: go into the cell in-game, and try to console-clicking objects which should be part of precombines. In the vanilla game, in a non-settlement, this should be pretty much everything.
Trees, houses, rocks, pieces of road, stuff like that. If precombines are intact, it won't work. You will either get "Picked non-ref object", or just won't be able to pick anything.

As for fixing it, only xEdit will work. You will have to identify which statics you touched, and remove their overrides.

- Will clutter and non-static objects be safe to move around, or should this also be avoided?

Non-statics are fine. Clutter is usually static objects, so it's usually not fine.

- If I move something accidentally, will deleting the changes in FO4Edit also restore any potentially-broken optimizations?

Yes indeed. There are two parts to precombines. There are all these precombines/previs settings in the cell itself. These shouldn't change if you just move stuff in the CK.
Then you have the actual objects within the cell. If you move them, they will create an override.
If the object was part of the precombines, and an override of it exists in your mod, it wil break precombines.

- Am I just being too cautious?

No, I don't think you are :D

[SKKmods]

To avoid touching any existing stuff by accident to move them and break things (1) create a new layer (2) make it active (3) lock all other layers (4) Check your ESP in xEdit for dirty touches and delete them.

[Aizekku]

Awesome! Thanks for the info - it makes me feel a lot more comfortable working with all this stuff. I've already added almost 200 new sources of radiation to the game.

 

Also, thanks for the tip about layers. I discovered this feature already and it's making me feel a lot more comfortable. My only concern with this is that it becomes difficult to pick new points to orbit the camera around. It makes it harder to navigate.

[Evangela]

That was...a bit confusing. Basically you can't touch/move anything.

[VIitS]

If something shows in xEdit as [Placed Object], it is part of a precombined mesh and touching it will break precombineds/previs if you don't rebuild them. If it does not have brackets, it is not part of a precombined mesh and you can do whatever you want to it.

[gob2]

Jumping in for a question....how about navmesh? If I add something that doesn't break precombines in a cell and then change the navmesh around it?

[VIitS]

Nope, you'd be fine. If you don't touch precombined REFRs, you won't break precombineds (unless you intentionally do so through CELL edits to remove them or using the relevant .ini edits).

 

The precombineds system does not care about navmesh, though the act of generating precombineds might build navmesh data into the mesh, based on some bug reports I have dealt with. I know it automatically makes the game treat precombined meshes as having the "Treat as Ground" flag, which is the cause of the "things sinking into the ground" bug you get with precombineds disabled in places like The Castle.