Discussion Scrapping Mods/Performance Issues

Discussion in 'SS Ongoing Discussion Forum' started by damanding, Aug 30, 2018.

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  1. damanding

    damanding Cluttered Mind Staff Member Administrator Support Team Vault Librarian Verified Builder

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    Feel free to ask questions or make comments on the Scrapping Mods and Performance Issues article I posted in the Educational Vault.
    What are precombines and why do scrap mods hurt performance?
    If you have ever used any sort of settlement scrapping mod you've run into an issue with something called precombines (a special sort of combined mesh new to Fallout 4) and therefore had a reduction in your game performance as a result. Precombines were designed by Bethesda to improve performance when rendering 3d items. To see additional aspects of the performance system designed for 3d items see Snarkywriter's thread for details.

    Technical explanation of precombines:
    "Precombination works by analyzing ref 3D for a cell and merging like geometries across similarly located refs into a different set of NIFs. For example if you had 3 refs to RockWithLichen and 1 ref to RockWithNoLichen tucked together in the corner of a cell, precombination would merge all 4 rock geometries together and all 3 lichen geometries together into a single NIF named for the combination key for that corner of the cell (eg: "Meshes\PreCombined\0000DBBB_01B8656E_OC.NIF"). The cell would store the form IDs for those combined refs so it would know not to load 3D for those NIFs in game since their 3D will already be baked into the combined NIFs." - Ziegfelding (Bethesda staff)

    ALL scrap mods that allow you to scrap items not normally scrappable in the vanilla workshop mode that scrap a mesh which is part of a precombined mesh will cause this problem of reduced performance. There is a mod for console users only that has previously claimed to bypass this issue but testing has confirmed that it also breaks precombines. This great video explains precombines in a fast, user friendly way and I highly recommend it.


    Use of the ini setting bUseCombinedObjects=0
    The only reason to use this setting ever is if you don't mind a significant performance drop throughout your entire game in order to be able to scrap items at non vanilla locations (whether you're using extended settlement mods, mod created settlements, or a system like Chesko's Camping mod). This is never recommended for low to medium PC hardware. Generally speaking it's just not a good idea to use this setting in general for any reason. Many users of Scrap Everything see it listed at the top of their description page and mistakenly think it's required to use but IT IS NOT REQUIRED FOR SCRAP EVERYTHING.

    Why do scrap mods create weird visual effects?
    In addition to the performance loss that happens when you break precombines, there is a secondary problem that scrapping certain items may also cause which is breaking previs. For the sake of performance the game's engine reads a special type of data (previs) that was generated with the Creation Kit which says if you're looking at a large item, items that are visually behind it and therefore not visible won't actually be rendered, therefore saving on the cost of rendering additional items. You may have heard of similar terminology related to previs such as preculling, occlusion, or occlusion culling.

    Technical explanation of previs:
    "Previs is precomputed visibility data and it is calculated using the precombined NIFs. It builds a visibility graph of which non-mobile uncombined refs and combined geometries are visible from different points which we then use in game for preculling the scene. This data is stored for a 3x3 collection of cells in the UVD files (eg: "Vis\Fallout4.esm\0000DBB9.UVD")." - Ziegfelding (Bethesda staff)

    Lets say for example that you scrap a large item that normally blocks your view of any items behind it in game. Some examples are the tall hedges in Sanctuary, the movie screen at Starlight Drive-In, and walls without windows or openings. If you delete those items you can experience visual glitches that can fade in and out as you change your camera angle.

    Additional problems with using scrap mods
    There are problems even beyond the performance drops that come with using scrap mods. Using Sanctuary as an example, if you use a scrap mod to remove the hedges, the building pads (left over after normal vanilla scrapping of destroyed buildings), or the non-destroyed buildings you end up with significant breaks in the navmesh of a settlement. Removing the building pads will result in a section of navmesh that floats above the ground. Removing things like the hedges or regular buildings will result in dead zones where NPCs can't walk at all. Even placing new flooring with navmesh in those locations may not work.

    Extended info on Navmesh:
    Navmesh is what tells NPCs where they can walk. For some reason Bethesda navmeshed the rooftops of the houses in Sanctuary which is why you can sometimes find your settlers or brahmin up there. When you first load the settlement into memory the game engine randomly assigns your settlers to a navmeshed location.

    When Bethesda marked objects as scrappable in vanilla workshop mode they're given a special tag that disables the navmesh underneath that object until it is scrapped. This way you can scrap a car and afterwards NPC's would be able to walk where it used to be. Scrap mods don't have a way to add new navmesh under the items that were not originally meant to be scrapped.

    Comments on "safe" scrap mods:
    People usually want to know what mods are "safe" to use. If you want a mod that is safe from harming your performance, there isn't one. Not even for console users. However there are two primary choices people pick from on PC, Spring Cleaning and Scrap Everything. Of the two I recommend using Scrap Everything as long as you don't change the ini setting (bUseCombinedObjects) from default.

    Details on which scrap mods to use:
    Spring Cleaning was abandoned more than 2 years ago. It also has some technical issues such as workarounds for vanilla game bugs that no longer exist that make it less than ideal. The team working on Scrap Everything are extremely well versed in the precombines/previs system. While their mod allows you to break that system if you chose to anyway, they're also ideally suited for fixing it when it breaks beyond acceptable levels such as problems that were found in Vault 88 or the Mechanist's Lair.

    To my knowledge most scrap mods work the same way as Scrap Everything and are therefore as safe to use as Scrap Everything is. Some mods use alternative ways of doing things such as by scripting and I don't have sufficient technical knowledge of those mods to determine their safe usage.

    For even more technical details, particularly details meant for mod authors please see my older thread on this topic located on Nexus: Fallout 4 Optimization and Performance Systems Explained
     
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  2. woodfuzzy

    woodfuzzy Probably a Synth or... Verified Builder

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    One thing I'd like to add to the "safe scrap mods".
    Many of the "clean up" mods remove the junk by flagging it as Deleted. Which deleting anything is very bad.
    Besides the possible mod conflict caused when another mod calls on the deleted item, the biggest issue is..
    Every item that is "deleted" by a "clean up" mod will at some point respawn at the world center X:0,Y:0,Z:0, which is just under the building in front of Greentech Genetics.
    There's around 12 items there from a Bugthesda oops.
    But what happens is, with hundreds or thousands of items all spawned in the exact same position, it causes FPS to drop to 1 or less and will end up CTD.
    It's a very easy fix and very easy to tell if a mod has "deleted" items instead of marking the Initially Disabled using xEdit.

    So in short.. well a bit late for that!
    Always check any "clean up" mod to see how they handled it.
     
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  3. Whisper

    Whisper Well-Known Member Patreon Supporter Community Rockstar Vault Librarian Verified Builder

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    I particularly like the explanation regarding the way it screws with the in-game navmeshing. Having for eg Starlight Drive-In settlers spawning 50m in the air where the screen *used to be* is a mental image that is both hilarious and instructive.

    :acuteIt seems that the mantra should be: “Thou shalt not use scrap mods. Period.”
     
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  4. RayBo

    RayBo Well-Known Member Patreon Supporter Community Rockstar Support Team Vault Librarian

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    Great article, hahaha I have questions :bye


    1. Is “markfordelete” no different in that it also will break the precombines and cause a performance loss? Yes, I am a "markfordelete" freak, haha really the only word in my vocabulary that I can type quickly:rtfm:shok1

    2. Mods like: Sanctuary Lite – jenncave, and Hozsa’s various mods

    https://www.nexusmods.com/fallout4/mods/29610

    “Navmeshing has been completely redone to account for the missing houses so npcs can walk anywhere. NO deleted navmeshes.”

    So, though the navmesh has been redone but the precombines / previs are still broken? Thus, performance loss?

    More or less I want to know if I have lied to myself thinking 1 and 2 above were a better alternative than not using a scrap-mod?

    Point Blank Question is: is there no alternative or recommendation if a player wants a clean settlement? :cray go ahead tell me even if it hurts:shok:vava
     
    Last edited: Aug 30, 2018
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  5. Whisper

    Whisper Well-Known Member Patreon Supporter Community Rockstar Vault Librarian Verified Builder

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    So some thinking between random Friday insanities at work...

    Place Everywhere. As I understand it, the most/worst that this will do (in extra item selection mode) is mark things as disabled? What effect might that have, with the relatively limited items it selects and the navmeshes that are left behind?
     
  6. woodfuzzy

    woodfuzzy Probably a Synth or... Verified Builder

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    Sure.. open the CK and make your own mod that disables the stuff you want gone, fix the navmesh (IF necessary) rebuild the precombines & pre vis.
    Boom... clean settlement & no performance loss. And depending on how much you disable, it might even be a performance increase... although a very negligible one.
     
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  7. pra

    pra Well-Known Member Staff Member Verified Builder

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    Is it possible to rebuild precombines/previs for Scrap Everything or scrap mods in general?
    Editing each settlement in the CK first sounds like a lot of work :/ besides, I have no idea how to rebuild these things...

    But if it is possible to just do that in the CK, couldn't I just load SE and then do it? I read somewhere that if a scrap recipe for an object exists, it won't be added back to the precomb.

    Also, I'm kinda confused about something else I noticed with SE. It seems to affect areas outside of settlements, too. I have some extra settlement mods, and I noticed that without SE, some things are part of the precomb, but with it, they can be scrapped (albeit with Place Everything's extended selection mode). But why? Does make a certain object scrappable breaks precombs for all cells where instances of it are located?
     
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  8. damanding

    damanding Cluttered Mind Staff Member Administrator Support Team Vault Librarian Verified Builder

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    Sometime in the next week I'll gather up answers to all these really good questions and do a second post in the original article with follow-up. :)
     
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  9. woodfuzzy

    woodfuzzy Probably a Synth or... Verified Builder

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    If you run Spring Cleaning Compatibility Patch (nothing to do with SC) it stops SE from breaking precombines outside of settlements.
     
  10. Saiyaness

    Saiyaness Member

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    I didn't have any performance issues with Scrap Everything but I disabled it after reading how bad it is.

    Will that fix the broken precombines issue since everything comes back, or would a new start be preferable?
     
  11. woodfuzzy

    woodfuzzy Probably a Synth or... Verified Builder

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    It will, and depending on how much you scrapped and built over the scrapped stuff.. it will make a pretty good mess. LOL
    Generally, it's recommended to NOT uninstall SE mid run because of that.
     
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  12. Saiyaness

    Saiyaness Member

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    I used it to delete rubbish and leaves from various places at Sanctuary. Pick up a broom, people!!

    I fixed Taffington Boathouse with Snappy Housekit so had to go back and delete what I added (except the roof) and I haven't been to Murkwater to see that crap shack returned that I scrapped and plonked a pre-fab down on.

    Did I do anything game breaking? Am I okay to continue with Scrap Everything turned off now?

    It is nice not accidentally scrapping a road or house in Sanctuary and having to reload :p
     
  13. woodfuzzy

    woodfuzzy Probably a Synth or... Verified Builder

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    I just disabled it for the contest debug.. mid run... didn't hurt a thing. BUT I didn't build over top of big nonscrappable items. Which is the biggest issue folks have.
     
  14. Catallaxis

    Catallaxis Active Member Support Team Vault Librarian Wiki Contributor

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    So I’ve been experimenting with 3lric & Tim-Timman’s Scrap That Settlement, which enables the scrapping of many additional objects around every settlement, including things like the trash, leaves, and bushes scattered around Sanctuary. It is claimed that, unlike other scrap mods, STS does not break precombines. However, since STS is currently only available for consoles, nobody but the authors know about its inner workings, and their claims have been hotly contested.

    So first I built up the optimized Sanctuary Hills city plan to level 3 on my Xbox One X without STS installed. Upon approach from the direction of Red Rocket, there were momentary hitches to the framerate as I crossed the cell boundaries and the city plan spawned in. These leveled out after a moment and the game returned to 30fps; it then dropped to around 20-25fps as the whole city plan came into view at once. Moving into the city returned it to mostly stable 30fps. (Note: Performance settings were maxed out, including random clutter. Visitors were turned off, but that was because I already had a couple visitors from the NPCs Travel mod.)

    I then ran the same test, but this time I installed STS and used it to significantly clean up the settlement of trash, leaves, bushes, etc. I didn’t remove everything possible, but I removed a lot along the roads and inside the houses. I then built the city plan back up to level 3, and performance was ... exactly the same, or at least no worse. Installing STS appeared to have zero perceivable impact on fps or loading.

    I then built up Red Rocket’s optimized city plan up to level 3, while also using STS to significantly clean up the settlement, and everything is more or less the same as it was before. There are some loading hitches when crossing cell boundaries and framerate drops when looking at everything all at once, but it’s all stable with no major problems.

    When I get home, I’m going to do the same with Abernathy Farm to test STS with the full “triangle of death”. However, so far, Scrap That Settlement has passed these tests with flying colours.

    From what I can gather, talking to cadpnq, who in turn spoke with Tim-Timman, STS and STC really are different from other scrapping mods, but it’s not because they don’t break precombines. However, while other scrapping mods break precombines in advance to enable scrapping, STS enables scrapping and then breaks only the precombine of the scrapped object. Presumably, then, the more you scrap using STS, the worse performance will be as more and more precombines are broken. However, it appears that the performance impact of breaking a few precombines when cleaning up most settlements is negligible.

    Anyway, I’ll keep you posted with further test results.
     
    Last edited: Sep 7, 2018
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  15. woodfuzzy

    woodfuzzy Probably a Synth or... Verified Builder

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    It works just like the Spring Cleaning Compatibility Patch for Scrap Everything. It breaks precombines but restricts it to the settlement build area. Which is a very good, performance wise, way to do it. Because settlements have very little impact with precombines broken.
     
  16. Catallaxis

    Catallaxis Active Member Support Team Vault Librarian Wiki Contributor

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    Well, supposedly it doesn’t work like that, because Scrap That Commonwealth uses the exact same method but is not restricted to settlements. I haven’t tested it yet. The claim is, apparently, that it only breaks precombines of the objects you actually scrap. It doesn’t pre-break anything. Therefore, if you have the mod installed, but don’t use it, then no precombines get broken.
     
  17. woodfuzzy

    woodfuzzy Probably a Synth or... Verified Builder

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  18. Catallaxis

    Catallaxis Active Member Support Team Vault Librarian Wiki Contributor

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    I've seen it before, and it's one of the reasons I wanted to test it myself.

    Alright, so I upgraded the optimized city plans for Sanctuary Hills, Red Rocket Truck Stop, and Abernathy Farm to level 3--the dreaded triangle of death. I used the Xbox One X default performance settings, except I turned on "Random Clutter", and I turned off "Visitors". However, I already had visitors coming and going from the settlements because of the NPCs travel mod which was active the whole time.

    I used Scrap That Settlement to significantly clean up each settlement, removing trash, leaves, bushes, and some other things here and there.

    While there were significant drops to the framerate (15-25fps) when viewing each city in full from the outside, once inside the framerate was returned to a pretty stable 30fps.

    There were occasional hitches associated with building upgrades, and more severe pauses when crossing cell boundaries. However, I was able to run around in the triangle of death successfully, multiple times, and taking several different routes between settlements without a crash.

    Then I installed Scrap That Commonwealth and ran the same test again. This mod uses the same scrapping method as STS, but it applies to the whole commonwealth--pretty much everything is scrappable. If it broke the precombines, then surely it would have a significant impact on performance, and probably cause the game to crash. However, it didn't. In fact, the performance was exactly the same as before, but sure enough I could now scrap everything in the Commonwealth when I entered workshop mode. I was able to successfully run around the triangle of death with no problems.

    Now, I suppose that if I were to actually start using STC to scrap a lot of objects around the triangle of death, I would start breaking the precombines and eventually it would begin to impact performance and perhaps crash, but it should be safe to use elsewhere.

    So far, STS and STC have passed the tests. I'm going to experiment a little more, such as with downtown Boston, but I would now actually recommend people use one or both with Sim Settlements. Even if they have a very slight impact to performance, it's probably well worth it for the benefits they offer (such as cleaning up Sanctuary).

    However, people who use these mods should know that every time they scrap an object that is only scrappable because of STS or STC, they should think of it as similar to building an object in workshop mode. That is, the more they use STS and STC to scrap stuff, the more precombines in a location they're probably breaking, and the smaller their effective build limit will be.
     
    Last edited: Sep 7, 2018
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  19. woodfuzzy

    woodfuzzy Probably a Synth or... Verified Builder

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    That's kool! At least console users have a little something to clean up with. :)
     
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  20. Catallaxis

    Catallaxis Active Member Support Team Vault Librarian Wiki Contributor

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    We'll have to hold the applause yet, because my final test is proving more problematic: Downtown Boston.

    It's fine with STS, but STC is having some issues. It does feel like possibly broken precombines, though it's unexpected after the triangle of death test, so it's possible that something else is going on.

    Unfortunately, I'm not testing this on a very clean save, so I can't rule out compatibility issues with other mods. I may have to start a new game and run just STS and STC together to test this properly.
     
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