That's Lit 1.0.7

Emulate vision for AIs, so they overlook you when you are blended in the shadow, or notice you faster when you are lit up.

That's Lit

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[NightFactory Engage]

This mod give AIs a chance to overlook you when you are blended in the shadow, or notice you faster when you are lit up.

It also introduce some randomness to AIs vision check to emulate how human space out or lose focus, if done right.

Developed with SAIN installed, should work fine together unless things change.

By default 2 meters are displayed at the top left corner. The first is score meter showing how dark (left) and how bright (right) you are, the second meter tells you how much AIs are affected. Can be disabled.

The goal is to give bots vision restrictions similar to human vision. With this mod installed, you can sneak around in night time and not always get noticed by bots from a distance, dash into bushes so enemies from afar may need to re-aim, or maybe get surprised by the fact that, the bot which have been pining you down didn't shoot at the very first moment you pop out of cover.

Most of the time on outdoor maps during the day, the mod does not much unless it's extra cloudy or clear, because the ambience daylight lights you up quite evenly, even under most shadows. But when the sun goes down, the score will start to react how you are lit up.

The most direct way to feel it is go to night factory and look at the meters as you move.


The only thing this mod change is a number called SeenCoef, which determines how long the an AI need to have you in their vision to recognize you.

The SeenCoef is modified by some calculation with all these factored in:

  • Time and cloudiness determine the ambience lighting in raid, as you may have know. Lighting is the core factor of this mod.
  • Sudden brightness change slightly makes your more noticeable (ex: walking into bright area or under flashing lights)
  • Getting lit up flashlights, gun flashes or thunder, breaks your sneakiness
  • Active light or laser just breaks your sneakiness (including IR if the AI is using NVGs)
  • AIs using NVGs are quite unaffected by darkness, especially at close distance
  • Distance matters. Darkness is less effective at close distance. Bot aiming with sights are less affected.
  • Rarely AIs vision check just fail, with the distance and your pose taken into account
  • Staying close to multiple bushes give AIs a chance to lose track from afar

You won't be invisible with a -1 (all left) score, it only makes AIs have quite a chance to overlook you.

Also noted that AIs don't always relies on their vision to detect you, especially with SAIN installed, they may act in response to noises you make.


This is a client mod. The downloaded DLL file should go to BeplnEx/plugins.

Calibrated Maps

In EFT, every map has different lighting characteristic, so the light detection need to be manually calibrated per map.

Here is the list of calibrated maps, That's Lit is only enabled on these maps:

  • Lighthouse
  • Woods
  • Factory (By default day factory is disabled because the lighting is basically all the same)
  • Shoreline
  • Reserve
  • Customs

The calibration is a very very very tedious and time consuming process, if you find issues and want to help out, turn on Debug Info, take screenshot and send it.

Fun facts

  • What we see in game is not what is actually observed by cameras. The presented visual is heavily processed.
  • We don't really have body parts other than arms and legs, so a lot of light run through where the thorax should be.
  • The mod create a camera to observe the player's body so it can know how the player is lit up.
  • The above 3 facts combined, is the reason why the light detection is not die accurate. It involves a lot of damn stupid math to make a alright estimatation for different time and weather on all the maps.
  • I knew nothing about how modding works for this game, like even how mod files should be structured, so I just download Soralint's SAIN then removed most his stuff and started to work on it. Also I took a helper class from SAIN, so a lot thanks to Solarint.
  • Version 1.0.7

    • That's Lit will be disabled by default from now on for maps not yet calibrated because the light detection could be very wrong. But can be enabled in configs.
    • On disabled maps vision randomness and foliages still work, just lighting doesn't affect anything.
    • Streets can not be enabled and may not be supported in near future because the lighting there is kinda craaazy.
    • Lab & Interchange are not yet calibrated because I've never been there.
    • Some calibration to Day Factory (Disabled by default because the lighting there is dead stable), Customs, Woods.
    • Added configs for less frequent foliage and equipment lights check.
  • Version 1.0.6

    • Fix "Make bots unaffected for a moment after it has vision"
    • Balance extreme darkness at close range
    • Config descriptions
    • Ineffectiveness of darkness against AIs using NVGs no longer scale with distance
  • Version 1.0.5

    • Balance close range sneaking with low score (< -50%)
    • Improve detection of flashing environment
    • Fix exceptions when detecting equipment lights
    • Add a HUD hint for people who hate it but don't know it can be disabled
    • Make bots unaffected shortly after perceiving the player (ex: Not affected after just getting shot by player in the shadow)
    • Minor fixes...
  • Version 1.0.4

    • Improve Night Factory detection
    • Skip foliage check in Factory or Hideout
    • Scale down the effectiveness at close distance so AIs won't overlook you even when you are basically already kissing
  • Version 1.0.3

    Fix for Hideout.

  • Version 1.0.2

  • I really hate that lazy BSG did not make such feature as default. I am using AMANDS mod and when I am trying to play at night I see nothing, just blackness/darkness. But AI are like Predator from the movie. They see me like it is a day for them. It pissess me off. I do not care to much about shadow stealth ETC but I really would like to have mod making AI be like me and with naked eyes they should not see me as I do not see them in total darkness. Vanilla EFT is just crap and I am happy to see someone have skills and approach this aspect of gameplay. I read comments and I am concerned about FPS issues as I already had to use moding to reduce AIs on map because they crapped on my FPS. So I would not want to cause hit on performance with this mod.
    So I ask, would be there some version that focus mainly on night AI vision and not try to also do the shadows calculations?
    I read about SAINS mod and that it also do some tweaking for AI sight at night but I am on 3.4.0 AKI and his mod does not support older AKI versions.

    So I wonder how "thats lit" mod is configurable to make it not hit FPS but make night a nightmare for AI as it is for me. I would really like to take advantage from my NVs but AI does not care and they are like born with NV in their eyes thanx to silly BSG way of thinking and executing this game features.

    • I am not sure if I understand, you want AIs unable to see you in the night time even if you stand in a spotlight?

    • Also That's Lit will not support older versions either.

  • Last release explains mod behavior on streets, cheers.

    • I will need a total different implementation for the streets ;(

      Yet it still won't be perfect until they clear out buggy lighting objects.

  • whilst i love the concept of this mod, i am getting massive FPS issues with it installed i get 30-60 fps less on customs when i install it and as soon as i remove it i have no issues

    • That's unfortunate. I have a few questions that may help sort out the issue.

      Do you see cpu or gpu usage higher than usual?

      Is the fps drop continuous or intermittant?

      Does it happen with more bots nearby?

    • the issue starts as soon as i spawn in,
      i normally get 120fps at the start of the raid and it drops to around 60-90 after about 5 mins after the bots have all spawned, but with this installed i start out at maybe 80 if i am lucky but more often about 60-70
      i will have to wait to check the GPU usage and get back to you

    • I need mainly the CPU usage :thumbup:

    • ok so
      no mod = CPU 55-75% / GPU 90-100%
      mod = CPU 55-75% / GPU 50-60%

      so for some reason with this mod installed GPU usage gets cut by half even when disabling the mod in F12 menu the FPS/ usage stays the same only once i uninstall it does the FPS/GPU go back to normal

    • I also have some horrible FPS when I have this on

  • Could you please provided a better explanation for the config?

    Specifically, do I decrease brightness impact scale and increase darkness impact scale to decrease overall vision? (Not my intention, just how I'm wording it)

    Otherwise, great mod! I've noticed a pretty big impact in maps like factory and customs!

    • Yes.

      How about these description? "Scale how AI noticing players slower due to darkness." and "Scale how AI noticing players faster due to brightness."

    • That's a perfect description. Thank you!

  • Idea for your next mod (if you want to work on a similar mod that is) put yet another camera rendering the ground (and/or) walls around the player (I'm not sure how, but I think there is a way to mask the player out of camera rendering)
    Check how similar the player looks to their surroundings, and mix that into your formula to consider "camouflage"? (like, if player is wearing green near some bushes, the ai should take longer to see them.) You can even mix the movement speed of the player since our eyes have an easier time noticing motion.

    Thumbs Up 1
    • I def have thought about it but that can't work because the camera doesn't see what we see. I can calculate how "white" it is but not the color looks to human, from basically a silhouette (the pixels are almost black).

    • You can do the metal gear solid aproach and just check the texture that the player is standing on. You also need to assign to each outfit a camo index for each type of texture.

    • That doesn't sounds like an ideal solution for EFT. Let's just say we don't always prone and bots don't just observe you from one angle; you may looks similar to the grass ground, but not the sky or wall behind you.

      I've never played MGS so I could be wrong, but I feel like the sneaking is far from serious, for example, the cardboard boxes.

    • Hmm. Are you making the camera render only the lighting information to a render texture and averaging that to get the resulting light/darkness value?
      I don't know how bots start detecting the player, but perhaps we could inject that detection function in such a way that once a scav starts detecting the player, two cameras that is some certain distance away from the player could be spawned facing the player rendering in color (without post processing or fancy shaders if possible, only textures). One of the cameras could mask the player, while the other is rendering everything except the player. (We can do this using a single camera but it would probably require us to manually call the render function.) We could then take the average (and/or) the deviation within the textures to determine a "visibility score".
      I think this method could emulate both camouflage and light level detection(?) unless I'm missing something.

    • Sounds like you have a very clear idea how to make such mod, go ahead! I don't mind playing with more good mods :thumbup:

  • Sneaki Breeki time :)

    Happy 1
  • Getting this error spammed on console.

    2023-09-18 18:37:00.257 -04:00||Error|Default| 
    EXCEPTION: System.InvalidCastException: Specified cast is not valid.
      at ThatsLit.Components.ThatsLitMainPlayerComponent.DetermineShiningEquipments (System.Boolean& secondary, System.Boolean& light, System.Boolean& laser, System.Boolean& laserIsIR, System.Boolean& lightIsIR) [0x002ae] in <778da107e58f49b89fdae57e99591de4>:0 
      at ThatsLit.Components.ThatsLitMainPlayerComponent.Update () [0x004d8] in <778da107e58f49b89fdae57e99591de4>:0 
    2023-09-18 18:37:00.257 -04:00||Error|Default|InvalidCastException: Specified cast is not valid.
    ThatsLit.Components.ThatsLitMainPlayerComponent.DetermineShiningEquipments (System.Boolean& secondary, System.Boolean& light, System.Boolean& laser, System.Boolean& laserIsIR, System.Boolean& lightIsIR) (at <778da107e58f49b89fdae57e99591de4>:0)
    ThatsLit.Components.ThatsLitMainPlayerComponent.Update () (at <778da107e58f49b89fdae57e99591de4>:0)
    UnityEngine.DebugLogHandler:LogException(Exception, Object)
    Class312:UnityEngine.ILogHandler.LogException(Exception, Object)
    UnityEngine.Debug:CallOverridenDebugHandler(Exception, Object)



    Thumbs Up 1
    • Do you have a helemt and does it have light attached?

      Also maybe move this to the support thread.

    • I assume this is fixed in 1.0.5, do tell me if the problem still exists.

      Thumbs Up 1
    • Ran a few raids after updating and there are no console errors. Thank you!!!

      Happy 1 Thumbs Up 1
  • As someone who loves stealth options, if I can combine this with a suppressed USP and crawl around in dark rooms while the AI has no idea... oh hell yeah 8)

    Happy 1
  • i think this mod can become a part of Realism Mod

    • Does it have to? Or does Realism change bot vision too? Some said that also for SAIN, I just wonder why if it's working fine.

      To be honest the calculation for all the map + weather + time combos make me doubt others will want to understand the code to maintain it.

      It's nothing high tech or genius, just pure labour of restarting the game and rewrting the simple math formulas <X

      Thumbs Up 1
    • In some ways they're changes bot vision, but no one of them adds your "stealth" system

    • I don't know about Realism but IIRC SAIN doesn't change the AI vision logic, it just tweak the distance and speed. That's Lit blocks off AI vision by conditions not exist in vanilla, which kinda changes the behavior. Most importantly, they work fine together!

      BTW I am very interested to see if there's any sort of conflict between this and Realism.

  • this will become a must

    Happy 1
  • Ooooo I can't wait to try this out! More Stealth = More Better !!!

    Happy 1
  • thank you so much for this man, finally i can become sam fisher

    Happy 1
  • Sorry for rewriting

    Just tried it out on Night Factory ... Finally i can be sneaky and kill in silence. I like it very much. Would a mod like this work with noice? That would be the ultimate sneaky thing

    PS: i just tested it and noticed that i am totaly invisible for my enemies. What is a good setting to be sneaky but not 100% invisible?

    Thumbs Up 1
    • If you haven't, please try update to see if it's fixed.

      Thumbs Up 2
  • Made with SAIN in mind?

    Hell yeah! Gonna try this today.

    Happy 1
  • Чики брики в тёмку

    Happy 1
  • Brilliant idea and concept! Probably going to be the next life-changing mod.

    Happy 1
  • Hello, awesome idea! I've noticed there was a Foliage impact scale, how will this affect other mods like No-Bush-ESP? Theres no options/settings to the mentioned Mod

    Thanks again

    • No, the mod simply checks foliages nearby and factor it into the SeenCoef, which is the only thing this mod change.

      Thumbs Up 2
    • Also I personally recommend SAIN which contains NoBushESP + NoGrenadeESP + NoAIESP integrated.

      Happy 1
    • Hey i really appreciate the reply, ive only installed SAIN but never messed with the config, again thanks for the insight :)

    • You are good to go with this + SAIN, nothing to configure :thumbup:

  • That's lit indeed. Great idea and a unique method to implement it.
    That said. I'm also new to the modding scene. Having an extra camera to render the character seems a little processing intensive to me. How's the performance?

    Thumbs Up 1
    • I don't feel a difference at all, and I have a decent PC, so I don't have an answer for others.
      From what I've learned as an developer, I'd assume 1 more camera should be nothing much for PCs running EFT.

      Heart 1
    • I think it depends on the camera and its properties. Having an extra camera realistically shouldn't hurt much unless you're meant to actively look through it with magnification.

      (a little bit like how the regular EOTech or Aimpoint doesn't hurt performance at all, while PiP scopes like the magnified EOTech or DMR rifle scopes really shit on performance)

      Theoretically, just observing the body simply to measure light levels and not magnify shouldn't really do much. That said, Tarkov and optimization are not friends, so I would expect any mod with an additional camera to potentially impact framerate whether it's negligible or not.

      Heart 1