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Interior cell best practice: Precombine/Previs or Room Bounds? Does it matter which is used?

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#1
RedRocketTV

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Looking for some guidance/input on the best practices for FO4 interior cells regarding pre-combined meshes and previs. I know this topic has been beaten to death. I’ve read some very informative threads here on the forums that address the issues with regarding pre-combined meshes and previs for interior cells, and that’s sort of why I’m asking for input.

 

I’ll try to make this as much to the point as possible while still giving relevant information: I have an interior cell for a new player home built from scratch, not copied from an existing cell. The player home is what I would call large, “real world square footage” wise it might be about half the size of the Third Rail cell.

 

I had not intended to go through the pre-combine/previs process for two reasons:

1. I’ve had dismal failures in my previous attempts at doing this in exterior cells

2. I didn’t precombine/previs in my previous player home mod and in all my testing there were no performance issues. Granted, the cell for that home was VERY small. 3-4 times smaller than this one.

 

I’m maybe 3/4 of the way through the project and am wanting to start the decorating phase. Before getting too much further I decided to test the mod on my “potato testbed” laptop. My dev machine is rather beefy so I test all my mods on the potato at various stages of my projects. The potato is an older ASUS ROG laptop, i7-4700 2.4Ghz, 24GB RAM with a GTX 860M. I work under the assumption that if I can get a mod to perform well on that machine, then it should perform well for most users with equal or better hardware.

 

Testing the new mod on the potato I was getting many spots in the house where the fps would drop to the mid-to-high 40s. Not acceptable to me. Especially since I haven’t even started my decorating and clutter phase yet.

 

I tried going the precombine/previs route to see if that would help...which it did somewhat, but I the material swaps for all my walls were missing. I even tried recreating the precombine/previs in the CK on the test machine, same result. These material swaps were customs swaps done in the CK using vanilla material files to replace wall textures. 

 

To clarify, "No Previs" in unchecked in the cell settings. I’ve run Clear Affected Cells for PreCombine Data, then Generate PreCombined Visibility for Current Cell as outlined on the many Nexus forums I’ve read on this subject. For whatever reason, the material swaps are being ignored, not read, whatever. And the frame rates were still not what I would call acceptable. 

 

Just for kicks, I split up the cell into sections with room bounds and portals to see if that would help. It did. Immensely! The potato now gets a solid 60fps in all but a few spots where I have shadow generating lights and multiple dust/mist FX. Even then, it never goes below 50. That to me is much more acceptable. And setting up the room bounds and portals was far less painful than I had anticipated.

 

So my question is this: What is the best practice for interior cells? Is it enough to go with room bounds and portals if they work and address the performance issues? Is it really necessary to worry about precombined meshes and previs if I have the performance up to an acceptable level? I'd rather not have to troubleshoot the missing material swaps from precombining the meshes if I can get away with it.

 

Does anyone else build interior cells just using room bounds? 



#2
Trosski

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Precombine/Previs is only intended to be used outside. Previs data tells the game what should be visible in your cell from adjacent cells. Being a solitary interior cell... that serve no purpose. The Roombound boxes and portals are meant to limit how much of the cell is rendered at one time. it keeps only the room you are in rendered, and anything in the line of sight through your portal. This tutorial is for the old skyrim CK, but it's still relevant.



#3
RedRocketTV

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Thanks, Trosski. That's just the sort of confirmation I was looking for. My uncertainty was coming from some threads here discussing people having problems with preculling and previs issues while editing vanilla interior cells combined with my examination vanilla interior cells in the CK. In the vanilla cells, there seems to be no consistency of where and when room bounds are used. Larger interior cells where I would think room bounds would be needed don't use them, while other interior cells of comparable size do use them. Color me confused. 

 

It seems all interior cells I've examined have the "NoPrevis" box unchecked in the cell info panel unchecked by default. But I know that previs is useless unless you precombine meshes first, so that makes me think vanilla interior cells were using precombine/previs which leads to people having issues while editing them.

 

In my case, setting up room bounds and portals resolved the performance issues on my test machine so that really seems the way to go. I'd much rather deal with room bounds and portals that I add myself and have total control over. My limited experience with having the CK generate precombined/previs has been less then successful and has actually degraded performance in some cases. 

 

As I start creating larger interior cells, I want to have a plan for optimal performance on lower end machines. This has been helpful. Thanks very much! 



#4
VIitS

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Yeah, it's fine just using roombounds and portals for an new interior cell, as long as you do them right (which it sounds like you are). The problem people were having with existing cells is that Bethesda did a absolutely horrible job with roombounds and portals, I honestly don't think the person(s) responsible for doing it had a clue how to use it right.

 

It also has the advantage of continuing to work fine if people are using the no previs and/or no precombineds ini edits.



#5
RedRocketTV

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Thanks, VIitS. I appreciate the input. The only real issue I had setting up my room bounds was that because of the house design I had to create them vertically on multiple levels, as opposed to horizontally as you would in a traditional dungeon type cell. It took some tweaking and testing to accommodate items (such as wall sections) that may have been set into the floor at points where the room bounds met vertically between levels so things wouldn't disappear. But, that's why we test. And test. And test.  :cool:

 

In any event, I appreciate your comment as it puts my mind at ease about the direction I'm going with in optimizing this mod. 







Also tagged with one or more of these keywords: creation kitinterior cell, previs, precombined, room bounds

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