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Fallout 4 Optimization and Performance Systems Explained


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Removed or disabled objects won't disappear if in PreCombines, but if you disabled precombines (no PCMB) then they should have gone.. Perhaps as you say some scripts are controlling them, or they are parent enabled. Odd though. 

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You can disable any script related reference by tracking down the script and swap the reference in the script itself by a replacer, e.g. a blanked static object. this works mid game. currently i dont see any reason to use PreCombines or PreVis in an interior cell. To some extend at uGrid 5 it is not even required for exterior worldspace.

I do not understand why the devs did not combine the static ollections of e.g. skyscraper as one object with just one texture/material reference instead they used tiny bits of static objects which in collection build the a super composition / skyscraper, which then needed PC or PV probably for console users/gamers. It would probably work far better to combine such buildings and many other object into one object and texture etc. in the first place. Then they added alot of trash piles not immersive for post 200 years maybe soon after the war... which bloat the game even more with texture reference overkill then many texture for small objects are 1k+ ... its a mess.

Also modding those cells is a pain in the a** thanks to all of this.

 

Edited by Qrsr
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One of the issues is, Beth used previsibines not only to paper over shortcuts in worldbuilding but also to mask away bugs in the engine. 2 examples:

- Havok object CTD in very densely populated areas
- Texture smear bug in very densely populated areas

So if u turn precomb/previs off, these hidden but lingering issues are then going to become problems again.
I also suspect this strategy of tryna sweep tech debt under the rug has come back to bite Beth in the ass more than once already.

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I've only seen the texture smear caused by precombines (a dodgy mesh precombined) - not prevented by precombines... Do you have an example so I know what it looks like? And havok hates confined spaces - is that what you mean niston?

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So if i would remove the PreCombine and PreVis flag of any exterior cell and then create a bunch (alot) of SCOL for any building especially the boston area would this, could this even decrease performance load? I was reading about everything i could find about SCOL and its a far superior method at least if the statics combined share all the same texture paths. Then the game uses these SCOLs similar in function to PC/PV objects.

The most important factor would be that any cell can be modded now without fearing stuttering and else formerly caused by broken PC and/or PV - since both flags and any reference in the cell header is disabled.

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2 hours ago, PJMail said:

I've only seen the texture smear caused by precombines (a dodgy mesh precombined) - not prevented by precombines... Do you have an example so I know what it looks like? And havok hates confined spaces - is that what you mean niston?

Re texture smear bug:

1) Turn off previs and precombines system wide, through fallout ini file.
2) Go to the library downtown and look towards trinity tower, panning and tilting the camera a bit - you'll notice it looks like this.
3) Travel on foot to Goodneighbor - You'll notice it numerous times more (until you CTD, see below).
4) It also happens when u go to Bunker Hill and look towards the Boston skyline.
5) Another spot is in the parking lot behind Diamond City,  looking towards the towers or the stadium
6) Yet another spot is in Lexington at the Mystic Pines location, looking towards the corvega plant.
7) It's mostly dependent on viewing angle, with the bug vanishing and reappearing as you pan and tilt the camera around.

If you're adventurous (highly NOT recommended):

* Reprocess all your textures to contain NO mipmaps
* Retry the above steps and notice the bug is gone

Re havok CTDs:

Ever had the Basketball or some other random vanilla physics object being listed in a Buffout crashlog near the top of the stack? And when you remove the object in question from the cell, another random object causes a CTD? It happens all the time in downtown, when precombines are disabled for the entire game.

Pretty sure in both cases the issues are caused by data corruption from engine bugs that become apparent only when there is a sufficiently large number of references in the scenery. In case of havok, the corruption causes a CTD. In case of the textures, the corruption causes wrong parts of the wrong textures  being selected and getting drawn in a wrong way with a wrong mipmap level onto wrong geometry. As precombining reduces the amount of references (probably quite drastically in some cases), the faults are masked by the previsibines system and Beth therefore didn't give any f*#@s about saw no immediate commercial incentive to fix them.

But perhaps both issues could be rectified with some f4se dll black magic.

 

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@niston

Quote

Pretty sure in both cases the issues are caused by data corruption from engine bugs that become apparent only when there is a sufficiently large number of references in the scenery.

I think thats the case with many more things not just PC or PV. In this case collecting/merging the texture paths of certain objects by creating SCOLs and remove alot objects will ultimately let the engine shine under a new umbrella. The more i read the more i will duplicate the world space and see what i can do by playing around.

Edited by Qrsr
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6 hours ago, Qrsr said:

The more i read the more i will duplicate the world space and see what i can do by playing around.

I suggest converting one of the downtown towers into a SCOL for testing?

The big downside of all this precombining business (SCOL Generator and Precombiner use same code and suffer from the same inability of dealing with full precision meshes) is the loss of modability, ofc.

If Beth had made Trinity Tower a single object instead of insisting on their worldbuilding kit approach, I would not be able to "easily" repair and/or modify it without any 3d modelling skills and tools. Otoh, their choice of occlusion culling tech (Umbra) cannot efficiently operate on large collections of small objects, hence the precombines.

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On 2/25/2024 at 3:28 PM, niston said:

The big downside of all this precombining business (SCOL Generator and Precombiner use same code and suffer from the same inability of dealing with full precision meshes) is the loss of modability, ofc.

Yes and no. Some objects can be SCOLed while other should not. At some point a compromise is inevitable. Im not sure yet in how much it would affect shadow/sun effects (lighting) to the better. Since its a huge performance affector in downtown together with mist, fog, etc. the static objects in comparison have a far less impact while texture size may outclass mist, fog and light at some point, where there is/are many texture calls, e.g. loose objects (not SCOLed, or PC)

Quote

If Beth had made Trinity Tower a single object instead of insisting on their worldbuilding kit approach, I would not be able to "easily" repair and/or modify it without any 3d modelling skills and tools. Otoh, their choice of occlusion culling tech (Umbra) cannot efficiently operate on large collections of small objects, hence the precombines.

All of this "magic" would be less needed if world maps would see far less trash objects. If you count all the trash piles, debris etc alone and the textures the game needs to render in real time or not its insane. If all of this trash is less and textures rendering unified into certain mega objects (SCOL or no) i assume it will alone see a huge performance gain on top of that better min maxing of certain texture size (512 vs 1024 vs 2048 etc) on top of this the endless mist fog and god ray performance decrease technology. The game is bloated with all this. If such effects are available all the time there is no unique moment anymore and the effect not noticable and subconscious subconciouse thus obsolete by quantitiy alone...

Edited by Qrsr
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