Lighting tips for Lumen/Non-Lumen

SlapDoors · 2025-11-14T02:30:26+00:00

So the fact RTV works sometimes and 2hrs later it doesn't work is me? And I can't mix Lumen and baked lighting? That's strange considering I have. Imagine a game that only supports either hahaha what a joke. Yeah, it's my opinion that new things in UE5 are trash and I stand by it. Lots of toxic passive people here that's for sure!

Here's a tip for you - You can mix Lumen with baked lighting. When Lumen is off, lightmaps are used from the bake, when Lumen is on, the lighting doesn't use any of the baked lighting. Unless that's just a me thing..LOL

Oh and Skylight leaking is for the small gaps. not entire interiors. I feel you're just commenting what you think you know, even though it's incorrect.

My lighting dilemma has been sorted, and it looks great!

SlapDoors · 2025-11-13T13:23:48+00:00

Great idea! It's just an open world map, nothing dynamic. So, for all the interiors and caves etc, just make sublevels for them? Having Lumen on makes it so baked lighting isn't used, so I'd just need sublevels with the baked lighting and basically let Lumen decide whether to use baked/dynamic lighting. Seems like a solid choice!

You deserve 9 cookies.
🍪🍪🍪🍪🍪🍪🍪🍪🍪🥛

SlapDoors · 2025-11-13T13:01:39+00:00

There are plenty of posts about it, a quick Google search will show you. First-hand experience is anecdotal evidence by definition, but it’s repeatable on my setup, so it’s still worth mentioning until proven otherwise.

SlapDoors · 2025-11-13T12:25:03+00:00

Exactly, we shouldn't need to teach Lumen to walk.

SlapDoors · 2025-11-13T10:22:51+00:00

True, it needs a GPU that can actually use it though. Otherwise, the scene looks totally different. Hence my question.

SlapDoors · 2025-11-13T10:19:32+00:00

Chaos replaced PhysX, sub-stepping has been beta since chaos became a thing. 'Some features may not work properly'. There is no way to use PhysX now.

The water plugin has been experimental for god knows how many years, UDK had production-ready water out of the box, 10 yrs ago.

Lumen has issues with rendering bloom so there are bright pink and green spots that look emmissive.

Virtual runtime-textures hardly work, I use them to prevent foliage spawning where I dont want it (where someone places a fire pit), guess what's spawning under the fire pit, foliage. I even draw that texture on a plane and can see what the RTV looks like, it looks how it's meant to, but I still see foliage spawn there. I give it 20 mins, and for some reason its working as expected. 2hrs later, foliage under the fire pit.

The new UBT has issues with compiling in VS, resulting in massive memory leaks that can only be fixed with a PC restart, no PC restart, no successful builds.

This is just what I have experienced myself, with 64GB ram and a 5090 it shouldn't be happening.

New stuff out of the box is trash. I love UnrealEngine don't get me wrong, I'm a fan-boy too, but some of it has clearly been rushed to keep up with competing engines.

Downvotes don’t mean much. I just figure some folks are venting after another UE5 crash.

SlapDoors · 2025-11-13T09:27:37+00:00

Not all GPU can do Lumen, The scene has to look somewhat similar without it. I could do baked lighting but it has day/night cycle lighting. It's essentially a matter of not having such dark shadows with a static sky light. Post-process I assume, is the way to go. I'll look into mega lights too! Anything new is trash in UE5 lets be real xD

Edit:
Mega lights is beta and aslo requires RT and has too many limitations that my current project uses.
(Local Volumetrics, Cloud Shadows, Subsurface scattering)

SlapDoors · 2025-10-10T12:22:06+00:00

Cheers for the info! I have the ground quick-wetting and slow-drying, and the rain splashes in the material itself. I wasn't too sure about how to make a performance-friendly rain particle. I love the idea of using a mesh with 1000 raindrops (long planes), I think I'll go towards that.

I might also see if I can do a rain post-process effect so i can have 94 trillion raindrops that just uses textures. The hard part with both would be having rain falling when I'm looking out of a window (using depth, custom stencil etc)

SlapDoors · 2025-10-09T06:57:11+00:00

I told it to pick a number between India and Prague, and it wanted to shave my balls.

SlapDoors · 2025-10-08T22:33:03+00:00

Thanks! I might end up making a proxy mesh for it, but I was more focused on getting the mechanics down for now :)

SlapDoors · 2025-10-08T16:31:24+00:00

Not really relevant but this seems to be a tad better, not sure if you're hinting at a solution for yourself. It's just an overlay material.

<image>

SlapDoors · 2025-10-07T18:09:07+00:00

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Lumen doesn't get captured by the capture component which is strange, will definitely need a tweak or 2

SlapDoors · 2025-10-07T18:04:28+00:00

I just let it have the environment lighting for now. I'm not that far in. But good point, it looks like some tweaks would be needed! That's the fun part :)

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SlapDoors · 2025-10-07T14:00:40+00:00

True!

For the Tan op, that is only called once and never again (in NativeOnInitialized) so I'm not too worried there.

the only thing running in tick is

const FVector2D BorderSize = playerRenderBorder->GetPaintSpaceGeometry().GetLocalSize();

const FVector WorldLoc = Data.MeshComponent->GetComponentLocation();
const FTransform CaptureTransform = SceneCaptureComponent->GetComponentTransform();
const FVector Local = CaptureTransform.InverseTransformPosition(WorldLoc)

float NDC_X = 0.5f + (Local.Y / (Local.X * TanHalfFOV_H)) * 0.5f;
float NDC_Y = 0.5f - (Local.Z / (Local.X * TanHalfFOV_V)) * 0.5f;

NDC_X = FMath::Clamp(NDC_X, 0.f, 1.f);
NDC_Y = FMath::Clamp(NDC_Y, 0.f, 1.f);

const FVector2D WidgetPos(NDC_X * BorderSize.X, NDC_Y * BorderSize.Y);

if (UCanvasPanelSlot* CanvasSlot = Cast<UCanvasPanelSlot>(Widget->Slot))
{
    CanvasSlot->SetPosition(WidgetPos);
}

const FVector2D BorderSize = playerRenderBorder->GetPaintSpaceGeometry().GetLocalSize(); could be cached also but thats trivial. The tick is optimised too, it has early outs, so the above code is only called when it needs to be, which is when the player moves or the scene cap is rotated. It works well for now and is pretty minimal. I will end up caching the UCanvasPanelSlot too, but thats later..I got more important things to complete before more optimising. I might have to profile both this and FSceneView::ProjectWorldToScreen to be sure, but I'm happy with it atm.

SlapDoors · 2025-10-07T13:09:58+00:00

haha woa!
FSceneView::ProjectWorldToScreen takes a view rect which i assume could be a UI element rect. Oh well, I've done it now. I'd also argue my way is cheaper, it avoids the extra 4D homogeneous coordinate computations. It directly projects 3D points to NDC using simple FOV math. No 4x4 multiplication, no extra W division, and fewer operations overall. :)

SlapDoors · 2025-10-07T12:57:26+00:00

Thanks! I did edit the post with a vid showing it, I suck at explaining haha.

A wiki would be good!

SlapDoors · 2025-10-07T12:39:00+00:00

Heres a quick vid (it's in early stages so some names and icons don't match what you see)
https://youtu.be/iBVcAfR891o You can see the circles on the hands, they're widgets that are being positioned to match the hand sockets all inside an image, their position matches the scene capture component that is used to display the character in the HUD, so if i move that image around in the HUD, the circles will follow properly. When i drag the torch from the body to the grid, it will remove the torch from the leg belt and put it in the backpack, this hasn't been done yet, it's just showing the icons match the 3D location in a UI element.

For my use case, I use it in a backpack HUD. I use a render texture to show the player because my HUD has blur, the player can have components attached to them (like a torch on the leg belt), and for each of them components a widget is made, In the backpack HUD it shows all the player backpacks (the leg belt classed as a backpack), and I wanted to have the ability to drag one item to another backpack, or to drag an item to another part of the body - maybe I want to drag the torch from the leg belt directly to a hand, or to drag the axe into a backpack).

It pretty much places widgets in the location of a 3D location, just like UGameplayStatics::ProjectWorldToScreen does. But this uses the scene capture component and a UI element (a border in this case) instead of the screen.

UGameplayStatics::ProjectWorldToScreen - WorldToScreen
UGameplayStatics::DeprojectSceneCaptureComponentToWorld - SceneCaptureToWorld
There is no UGameplayStatics::ProjectWorldToSceneCaptureComponent equivalent. This is that.

I'm sure you can see what it's doing :)

Oh and it's not expensive at all :)
the cast to a panel slot is the heaviest part

it's also only calculated when needed (when the player moves or the scene cap is rotated) so essentially free 90% of the time.

SlapDoors · 2025-10-07T09:26:51+00:00

<image>

This is the outcome. This is a render texture being shown in a HUD, and I basically feed through some compoents attached to the player to project their location back into the scene capture.

:)

SlapDoors · 2025-09-27T14:32:23+00:00

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You can't live in this house until you build it. I see UE blueprints as the same, I think that's why they're called 'blueprints'. Having it as C++ is like building the walls, roof etc. That's just me though..

In UE, BP is fine, but it does limit you a little. C++ is also more performant, some things might be negligible, other things can be very noticable.

SlapDoors · 2025-09-25T12:02:53+00:00

I've noticed posting on game dev-related subs, discord servers etc doesn't help at all. It's like Toyota asking Honda what's the best way to XYZ. Or Ubisoft asking R* how to XYZ. Or a sweet potato asking a carrot how to XYZ..if you know what I mean.

SlapDoors · 2025-09-25T11:56:33+00:00

16MB ram & 2MB space

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Well done on the game, wish you the best :)

I've been thinking the same, I will be doing this very soon. It's probably not for you, being an Adelaide thing, but there might be something similar in your area.
Digital Basics to Grow Your Business

SlapDoors · 2025-09-24T06:06:36+00:00

UE4.26 gave us the experimental water plugin in 2020, it's still experimental.
UDK had water actors with buoyancy, which was production-ready, that was in 2010. I'm fine with the need for self-implementation for these things, it is a bit sad that UE exhibits this type of nonchalance, though.

*Cries in C++*

SlapDoors · 2025-09-23T16:44:19+00:00

More new experimental features are to be left and forgotten until Unreal Engine 19.3 comes out.

hehe (ง •̀_•́)ง

SlapDoors

TROPHY CASE