Epic's GPUlightmass

Release 5.7.4 2026.05.10

https://downloads.luoshuangfw.io/gpulm-releases/GPULM-5.7.4.7z
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  • Add support for custom primitive data

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Surface lightmaps can be attached to them, though you probably need to toggle some settings about two sided in both material and component lightmass settings

THANK YOU!!!

is this possible in GPU lightmass?

It is implemented but only for non Substrate materials: Epic's GPUlightmass - #357 by YujiangW
I haven’t tested it for Substrate so idk if the automatic Substrate material converter can make it work

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Experimental: Graphical Installer 5.7.4 2026.05.10

https://downloads.luoshuangfw.io/gpulm-releases/GPULM-5.7.4-2026.05.10.exe
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Now you can install GPULM with this installer. It backups engine files so they can be restored during uninstall:

QKocXIdF5F

This isn’t just a QoL change; in the future I will start to modify engine runtime files, and I expect many of them will have only very small difference in binary. Packing all the changed files in a 7z archive will be infeasible because of size. This installer uses HDiffPatch to patch the engine.

The installer won’t try to restore files if it finds the files don’t match the version it has patched.

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any info on the next updates?
also wanted to ask, should i credit you in the reveal announcement of a project i’ve been involved in?

any info on the next updates?

I will focus primarily on VLM.

also wanted to ask, should i credit you in the reveal announcement of a project i’ve been involved in?

I’d appreciate that.

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:+1:
also, its a long stretch but since you’ll start to edit engine files, it would be EXTREMELY helpful if we could get some sort of “Do NOT Render with VLMs” checkbox on actors
we’ve been really struggling with lightbleeding into large actors like moving trains

i think at some point, i tried a horrible fix by rendering the train interior as unlit and then baking the lighting in blender and using the lightmaps in the shader

Did you try to force the train to use surface lightmaps?

yeah, but nothing changed on our end after trying that

Here, force surface makes the cube retain its lightmap. if you move the cube directly in the editor its lightmap will be invalidated though. this is driven by a sequence

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but this now gives us light bleeding from the lightmap
or do you mean i should put the train actor into a pitch black area and then teleport it to the needed area at runtime?

yeah you do need to sacrifice something

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at the very least, if that means it’ll be pitch black interior wise i can handle that, since my goal is to have no light bleeding at all and then light up the interior with movable light actors